The Risk/Award Ratio

Originally Published MDDI June 2001

Editor's Page

Behind the Glory of Awards Lie Some Tough Decisions

Donald S. Barcan
Dale Bevington
Krista Coleman
Joseph F. Dyro
Craig M. Jackson

As readers of this issue's special section on the Medical Design Excellence Awards will note, the 2001 gold and silver award winners represent some truly admirable feats in the design of medical products. But what will not be evident to the casual eye is the hard work, wrenching choices, and even high drama involved in the selection process.

The 2001 MDEA jurors pictured on this page spent many hours studying and discussing the materials submitted by the awards candidates. The final decisions were of course the hardest ones. The jurors were all aware of a degree of risk in their ultimate choices. While the design features they were applauding were clear, they could not assess the safety and efficacy of the products or the ultimate acceptance of the products in the marketplace. By definition, such assessments are outside the scope of the MDEA competition. But like it or not, the decisions of the jurors are inevitably measured against those familiar criteria. That the jurors were willing to assume this risk is a testament to their dedication to the medical device industry.

Risk, of course, is what the medical device industry is all about. No device can successfully tackle significant healthcare problems without addressing it. Just before this issue went to press, the jurors encountered a vivid example of this reality.

One of this year's winning products was a highly innovative surgical device from Guidant, the Ancure endograft system. This product built on several advanced design concepts to treat abdominal aortic aneurysms without requiring the large incisions typical of traditional surgical treatment. However, two months after the awards judging, Guidant responded to a number of adverse events involving the device by voluntarily suspending production and recalling all inventory. Such an action does not necessarily mean that the device is flawed or that its design features are not in fact worthy of recognition. Rather, it reflects the reality that taking on very difficult challenges such as aneurysm repair involves great risk.

For the jurors, learning of these developments meant they had yet another difficult choice to make. The rules of the MDEA competition require that a product already be on the market in order to be given an award, and allow for withdrawal of an award if the product goes off the market. So, despite their recognition of the many virtues of the product, and the possibility that it will soon return to the market, the jurors agreed that it was incumbent upon them to withdraw the award.

To us, such a decision is what makes the MDEA program so valuable to industry. Like medical device manufacturers themselves, the jurors are willing both to take risks and to take responsibility for their decisions. We applaud both Guidant and the jurors for their honorable courses of action.

Hans W. Kramer
Eliot S. Lazar
Tom Marsh
Herbert F. Voigt
Michael E. Wiklund

Copyright ©2001 Medical Device & Diagnostic Industry

Medical Design Excellence Awards 2001

Originally Published MDDI June 2001

The 9 gold and 18 silver award-winning products in the fifth annual MDEA program are each distinguished by their pioneering design and manufacturing achievements. To paraphrase one of this year's jurors, the designers and manufacturers of the products on the following pages sweated the details and paid close attention to industrial design qualities.

Innovative medical devices—particularly those involving concepts that are on the leading edge of modern technology—are often hindered by setbacks. Technologies that ultimately provide significant benefits are sometimes controversial at the outset and must withstand increased scrutiny. Soon after the announcement of this year's MDEA winners, one device was voluntarily removed from the market, and production and sales of the device were halted. In view of the issues that led to this device's removal from the market, the MDEA jurors elected to withdraw that award.

The MDEA program is presented by Canon Communications llc and sponsored by MedSource Technologies, DuPont Tyvek, Agion Technologies LLC, Battelle, Avail, Colorado MEDtech, IBA Medical Sterilization & Analytical Labs, and Medical Device & Diagnostic Industry.


Critical Care and Emergency Products

GOLD WINNER

Departing from the Tried and True

XCalibur mobile transporter 6
Submitted and manufactured by Ferno-Washington Inc. (Wilmington, OH)

The key to developing the XCaliber mobile transporter was to view the entire process from a new perspective. "One major challenge was the departure from tried-and- true roll-pinned aluminum tube structures," says David R. Linger, director of global product development for Ferno-Washington. "Going with glass-resin pultrusions and plastics was a cultural change at all levels." Taking the product from concept to market required the combined efforts of engineers, designers, prototype technicians, and technical writers. Linger adds, however, that the project "was championed by top management and ownership."

The result of this process was the creation of the first composite ambulance cot in the emergency medical service (EMS) industry. The XCaliber is used by EMS personnel to transport patients to healthcare facilities from diverse sites, including accident scenes.

The cot not only had to be lightweight while capable of bearing a substantial load, but also had to optimize the delivery of prehospital care, withstand outdoor elements, and meet rigorous crash-testing and federal standards. Analysis of marketing data showed two principal needs for a new cot: the capacity to hold larger patients and design features to help reduce the back injuries of emergency medical technicians (EMTs).

To meet these needs, Ferno-Washington chose new lighter and stronger materials: multilayer resin and glass composites and epoxy adhesives. The design team selected a pultrusion process for molding the structural frame of the cot. The use of composite materials also allowed the design team to meet the additional goal of producing an aesthetically simple and cleanable cot, with subassemblies that can be easily replaced by the customer using simple tools.

With its 600-lb capacity, the cot can accommodate very heavy patients—allowing the EMTs to simply raise the cot and roll the patient to, and then into, the ambulance, where the cot is then safely secured in a cot fastener. For very large patients, the team designed an auxiliary large-body-surface patient deck that mounts over the mattress and standard bed surface, and locks securely onto the main frame.

The transporter was designed to provide certain ergonomic benefits to its operators. Gripping surfaces were designed to provide superior grasping positions, and the frame is adjustable at each end to promote proper lifting techniques. The thumb-tab controls allow operators to maintain their grip on the cot while using the controls. The main frame of the transporter is constructed with an elliptical shape that enables additional helpers—who are often untrained volunteers—to grasp the cot easily and with a proper secure grip.

The application of improved ergonomics, the novel use of plastics and other materials, and other key concepts of the design process all required a new approach to product development, according to XCaliber team leader Jeffrey Flynn. "We took every liberty to innovate and still remain within the product specification," he explains. "The product that resulted was exciting because we made up our minds, as a team, to do what had never been done before without letting product history drive our thinking."

The design team also maintained a clear view of the relationship between product designers and consumers. Says Flynn, "I never forgot and I never let my team forget that the consumer is not usually the innovator. It is rare that the consumer says, 'hey, let's invent this thing to do this' and have a milestone product as a result. That's our job." He explains, "A product specification is fine, but it has as much to do with maintaining focus and direction internally as with meeting the needs of the consumer. To innovate, you have to reach out 10 to 15 years and discover what you want, as product designer, to be the mainstay in the market that far in the future."

An essential element in the development of the XCaliber patient transport system was incorporating a degree of unconventional thinking into the design process. Says Jeffrey Flynn, XCaliber team leader, "The challenges our team had to overcome included the 'build everything on the workbench philosophy.' Nothing beats a hands-on model, but refinement happens through iteration." On some aspects of the product, 20 or more iterations were performed on the computer before the design team agreed on form and function, according to Flynn. He explains that "the XCaliber was constrained only by a basic product specification, and any opportunity for major innovation was pursued. We never concerned ourselves with 'the way we've always done it.'"

SILVER WINNERS

Battlefield Tested

Life Support for Trauma and Transport (LSTAT)
Submitted and manufactured by Integrated Medical Systems Inc. (Signal Hill, CA)

The developers of the Life Support for Trauma and Transport (LSTAT) system strived to create a "smart" patient platform capable of functioning as a portable, networked intensive-care unit (ICU) and surgical table. Development of the product required approximately five years and was initiated by a brainstorming session involving military and industry representatives, according to Matthew E. Hanson, PhD, vice president for business development at Integrated Medical Systems. "What emerged was the vision of an individualized ICU that was both highly compact and highly capable, and could support an unbroken continuum of care from injury site, through evacuation, definitive care, and recovery," he adds. "In short, a 'trauma pod.'"

In addition to its 5-in.-thick patient platform, the LSTAT system incorporates a state-of-the-art defibrillator, ventilator, suction, three-channel fluid and drug infusion pump, point-of-care blood chemistry analyzer, and patient monitoring subsystems. Onboard power and oxygen subsystems are also provided. Patient data are available at the bedside on a handheld secondary display with optional wireless capability, over a hospital's clinical information system, and via secure Web sites designed to protect patient privacy.

Development of the LSTAT system required that a modular approach be taken in combining the functions of existing medical devices. Components are removed from their housings to minimize weight and volume, individual power systems are also removed, and inner circuitry is separated from the external controls and displays.

Data generated by devices produced by different manufacturers are ported to a common databus, individual datastreams are time synchronized, and a unified stream is then packaged in Internet protocol format for Etherport communication. The resulting product, says Hanson, "is the world's first FDA-cleared suite of diverse medical, data, and utility subsystems."

"Among the company's competitive advantages is its ability to 'leap frog' itself, to absorb customer feedback and rapidly advance to the next generation," says Matthew E. Hanson, PhD, of Integrated Medical Systems. "The LSTAT system has already evolved through three generations since the first functional prototype, achieving lighter weight, smaller volume, and greater capability."

Adding Versatility to Pulse Oximetry

Radical Signal-Extraction Technology (SET) pulse oximeter
Submitted and manufactured by Masimo Corp. (Irvine, CA)

According to Jeff Herbert, I.N. Incorporated sales and marketing manager, among the technical achievements of the Masimo Radical signal-extraction technology (SET) pulse oximeter was "integrating all desired features and specifications into a portable and modular monitor design that maintains comfortable, ergonomic, and portable form-factors, and still being able to meet environmental test requirements." The product is intended to provide continuous noninvasive monitoring of functional oxygen saturation of arterial hemoglobin and pulse rate for adult, pediatric, and neonatal patients in hospitals, hospital-type facilities, and mobile and home environments.

The device design allows the part of the monitor that contains the main pulse oximetry function to be separated from the base station during operation for use as a fully functional handheld monitor. Trending data stays with the handheld device and thus with the patient. A built-in gravity detector automatically rotates the screen orientation when the device is changed from a horizontal to vertical position.

According to Peter Lang, Masimo product manager, "A key design achievement was to incorporate all the diverse user and design requirements into a versatile, innovative product that finds application throughout the hospital and healthcare environment, while breaking the traditional system design limitations so commonly found with medical devices." Lang adds, "The device's SatShare feature allows the Radical to interface and upgrade virtually any existing patient monitors without any additional, expensive interface equipment. With the Radical a hospital can truly standardize on one product and pulse oximetry technology throughout all departments of a hospital."

SUPPLIER FILE: I.N. Incorporated (Los Alamitos, CA)


Dental Instruments, Equipment, and Supplies

GOLD WINNER

Promoting Better Oral Hygiene

WaterPik Flosser


Submitted by Volan Design (Boulder, CO); manufactured by WaterPik Technologies (Ft. Collins, CO)

This device does the unlikely," says MDEA juror Michael Wiklund. "It takes a task that most people hate and makes it fun—almost something to look forward to." Juror Eliot S. Lazar adds, "From a practical standpoint, it has a vast audience and a wide range of utility that may have a beneficial impact on a broad segment of the population."

According to Wiklund, "The jurors who tried it liked it and would have written a check on the spot for the product. That is evidence enough that the product is a winner, not only from a design standpoint, but from a marketability standpoint."

The Flosser is a lightweight, handheld device that is highly portable and easy to use. It was designed to address the 90% of the population that know they should floss but just don't do it. The filament action gently reaches between teeth and below the gum line to remove the plaque that is associated with causing the gum disease gingivitis.

The primary goals for the WaterPik Flosser were to create an ergonomically comfortable product that would promote periodontal care and would be easier to use than conventional floss. It had to be aesthetically consistent with typical bathroom decor and have a minimal footprint.

To accomplish these goals, the designers of the WaterPik Flosser incorporated a number of novel ergonomic concepts. According to Wendy T. Volan of Volan Design, "The designers deliberately angled the flosser at the tip to facilitate interdental insertion, carefully positioning the single control button on the neck of the unit and adding a soft-touch, rubberized grip for increased ease of handling."

The ergonomic form of the device evolved as an extension of the fingertip for ease of aiming the tip when it is in the mouth and out of view. This allows the tip to be used comfortably in the areas where plaque typically forms.

The Flosser's tip was specifically engineered to be flexible enough to provide a whiplike action without irritating the gums. In addition, the designers note that the tip can never break off between the teeth. The styling of the Flosser handle incorporates a gentle "s" curve into the parting line that, when set on the counter, keeps the device from rolling over and the tip from touching the countertop. The soft-touch surfaces add color and style while enabling users to maintain their grip even with wet hands.

The vibrating tip generates 10,000 strokes per minute, enabling the single-use nylon filament to clean and strengthen gums gently. It is intended for use by anyone age eight and up, including those with special oral healthcare needs such as braces, crowns, or bridges.

Says Volan, "The next generation of the initial Flosser is a rechargeable version. The battery-powered version was redesigned to accommodate the extra space needed for the recharging electronics." The unit consists of a soft-grip handle that accepts a single AA battery, a cartridge containing a month's supply of replaceable flossing tips, and a stand or charging base, depending upon model. Also available is a set of color-coded, snap-on hygienic sleeves so that multiple family members can share the device without sharing germs.

The development process used an "art-to-part" methodology in that all design information was generated and communicated digitally throughout the entire process, reducing rework and time to market. The original design definition data were used to develop the industrial design surfaces and renderings, engineering documentation, and a prototype for clinical evaluation, as well as for direct machining of preproduction samples, and finally for full-production injection-molded tooling.

According to Volan, the 12-month development process for the product required a cooperative effort by design team members. She explains that "a cross-functional product development team was assembled with members of Volan Design and WaterPik Technologies. Skill sets bridged marketing, engineering, industrial design, oral-care clinical studies, marketing research, manufacturing, and sales." Volan adds that "tight integration of the in-house and design teams resulted in goals and schedules being met."

"Ergonomics were the biggest challenge for this product," according to Wendy T. Volan. "Perhaps the most important aspect of the product design was that it should be intuitive to use and easy to maneuver for everyone—from preteens to senior citizens. Ease of use was considered fundamental to widespread product acceptance." She explains that the design team analyzed the ergonomics of flossing in detail. "The firm ultimately designed the lightweight, compact unit to act as an extension of the hand, capable of being manipulated with subtle fingertip control." Volan Design senior industrial designer Bill Stephens adds, "We designed the device in such a way that inserting the tip into your mouth is a completely natural movement. The shape of the Flosser is designed to act as an extension of your fingertip, making it simple and intuitive."

SILVER WINNER

Highlighting Whiter Teeth

BriteSmile 2000
Submitted and designed by IDEO Chicago (Evanston, IL); manufactured by BriteSmile Inc. (Walnut Creek, CA)

The design concepts behind the BriteSmile 2000 were focused on creating a patient-friendly, nonthreatening system that uses light and a proprietary gel for teeth cleaning and whitening. Care was taken to give the device a nontechnical presence for customers who may be anxious about traditional dental methods. According to John Warner, product manager for BriteSmile Inc., the principal challenges involved mechanical design, electro-optical design, chemistry, and clinical research. Says Warner, "The time frame was about six months. As a start-up company, it's important to test the business concept as quickly as possible."

The designers chose to use fiber optics carried inside an articulating arm to bring light from the device cabinet to the customer's mouth. At the end of the arm is a light head containing customized emitters that shine light in a constrained pattern on the customer's teeth. The use of multiple emitters to illuminate all of the "smile teeth" at the same time in order to reduce the whitening time to one hour is innovative.

There are three cone-clutch style hinges on the arm that are at rest in the locked position. To move the arm, the operator takes hold of the light head. The operator's hand is then automatically in the correct position to depress the activation switch. This simultaneously releases all three hinges by using air to force the locking mechanism free. Once the arm is in the desired position, the operator lets go of the light head, thereby releasing the switch, and the arm is again locked in position.

A pivot at the base allows the arm to be swiveled aside during gel changes and then brought back into the proper position without readjusting the hinges. It has the added benefit of reassuring patients that they are not trapped between the dental chair and the whitening device, since it can be easily swiveled aside if necessary.


Finished Packaging

GOLD WINNER

Extending the Shelf Life of TPNs

Kabiven multichamber parenteral nutrition packaging system
Submitted and manufactured by Fresenius Kabi (Uppsala, Sweden)

The clinical objective of parenteral nutrition products is to administer appropriate levels of lipids, amino acids, glucose, and electrolytes. Traditionally, such nutritional solutions for parenteral use have been packaged in separate glass containers and administered individually. Fresenius Kabi notes, however, that many hospitals had expressed a need for more-convenient, less-time-consuming methods for administering parenteral nutrition. Lena Soderstrom, the firm's director of project management, adds, "Compared with glass, plastic is lighter, flexible, and resilient to additional knocks. The current trend is toward total nutrient admixtures (TNA) and giving total parenteral nutrition (TPN) from one container made from plastic."

TNA is already a routine procedure in many hospitals and offers a number of benefits; however, it also involves consideration of such issues as metabolic efficacy, stability, and compatibility, as well as the risk of microbiological contamination during preparation and administration. TNA mixes have certain limitations; some must be mixed using a transfer set before administration, others have a relatively short shelf life and must be stored in refrigerated conditions until use.

The main design and engineering challenge of this project was to overcome the limitation of stability. Soderstrom adds, "to produce a product in an overwrap and then to do a final sterilization, and also to find a 'global' composition is a challenge." The path chosen for a portion of this challenge was to design a single package that holds the three TNA solutions separated by peelable seals. This optimizes the quality and the stability of the products while reducing the requirements for controlled handling and storage as compared with mixing a TNA.

The peelable seals make it possible for the end-user to mix the product just prior to use. Hospital mixing of individual solutions for TNA requires aseptic handling that, in order to obtain appropriate safety with respect to microbiological contamination, is time- and resource-consuming. Placing all nutrients in a single closed entity with separate chambers that allows mixing without exposing the solutions to the environment eliminates this work.

The system consists of a three-chamber inner bag enclosed by a cover pouch, both made of polyolefin polymers. The printed inner bag is filled with glucose, amino acids, and lipid emulsion in the three separate chambers. Peelable seals separate each chamber. At the time of use, the cover wrap is removed by tearing at a notch in the plastic cover and pulling it open. The cover wrap and an oxygen absorber, placed between the inner and outer bag to consume any traces of oxygen, are then discarded. The top peelable seal between the glucose and amino acid chamber is opened first. Gripping the sides of the bag above the middle of the seal and pulling the sides outward and downward in a circular movement using pressure from thumbs and index fingers opens the top seal. The bottom seal is opened using the same technique.

Alternatively, the bag can be placed on a flat surface and rolled open starting from the handle side. This opening technique could also be used with the overwrap still on. To get a homogeneous admixture, the bag should be inverted several times after the peelable seals have been opened before start of infusion. In short, to commence usage, the seals are opened, transforming the multichamber bag into a single compartment.

The overall packaging concept was developed for minimal environmental impact by choosing recyclable materials (no PVC or aluminum) that do not pose a risk of toxic emissions or by-products at disposal and waste handling. In addition, the waste volume is minimized, which is important in handling, transport, and landfill disposal. If the container is incinerated, the inherent energy can be reclaimed, according to the manufacturer.

According to Soderstrom, "We started with the packaging concept during 1995, the first stability batches were manufactured by the R&D department in 1996, and the first batches were produced for the market during 1999." The product has received approval for marketing throughout the European Community (EC) countries. Soderstrom notes that several improvements in the original design concept are already being made. "During this year," Soderstrom explains, "we have already made some bag enhancements. For example, we now produce our bags with premanufactured 'holes' in the 'welding shoulders' so that it is easy to hang the bag upside down, which is sometimes desired for the use of special additives."

Lena Soderstrom explains that Kabimix has to be stored under refrigerated conditions before use, and has a rather short shelf life. "The challenge, of course, was to find a more convenient way to package these nutrients, and better methods to administer them." She adds, "The main design and engineering challenge was to overcome the limitation of stability. With this in mind, we developed Kabiven, a three-chamber bag that can be stored at room temperature for 24 months."

SILVER WINNER

All-in-One Dental Adhesive Package

Prompt L-Pop
Submitted and manufactured by ESPE Dental AG (Seefeld, Germany)

The Prompt L-Pop is intended to provide an innovative tool to help dental professionals in bonding composite filling materials and fissure sealants to dentin and enamel. Says Oliver Frey, of ESPE, "The basic challenges to overcome in the development process were to develop a chemistry that would work reliably on enamel and dentin at the same time, to design a package that is simple to use although it contains two components, and to stay on time with the schedule."

The single-use package is divided into three compartments. The first compartment contains photopolymerizable methacrylates that are ester derivatives of phosphoric acid, a photoinitiator, and stabilizers. The second compartment contains water, stabilizers, and a complex fluoride salt. The third compartment contains the tip of a microbrush used to apply the filling material and sealant.

The package manufacturing process starts with vacuum molding the compartments into a special foil blister that is composed of three different layers, including polyethylene terephthalate, aluminum, and polyethylene terephthalate. This is followed by filling the first and second compartments with the components described above. The first foil blister is then covered with a second foil layer, which is sealed under temperature. The final production step is the insertion of the microbrush into the third compartment of the package.

Frey comments that "the package's key achievement, from our point of view, is the innovative design that is efficient and fun to use. In fact, the design is reminiscent of a lollipop—that's why the product name: Prompt L-Pop." The firm is currently redesigning the package slightly so the design can be applied to other products, he adds.


General Hospital Devices and Therapeutic Products

GOLD WINNER

Creating a Patient-Friendly Treatment for Lung Disease Symptoms

Acapella chest physical therapy device
Submitted by Product Genesis Inc. (Cambridge, MA); manufactured by DHD Healthcare (Wampsville, NY)

Acapella is a chest physical therapy (CPT) device that uses an innovative vibratory positive-pressure (PEP) therapy system, combining the benefits of PEP therapy and airway vibrations to mobilize pulmonary secretions. The product is intended for use by patients with lung disease and associated secretory problems, such as chronic obstructive pulmonary disease, asthma, and cystic fibrosis. Regular use of the device can significantly improve the clearance of secretions in a patient's lungs.

Chloe C. Beirne, marketing specialist with Product Genesis, says "the product's key attribute is its ability to deliver treatment to patients with severe lung disease who are unable to move from the reclining position." Beirne adds, "Additionally, existing systems required the patient to be slapped on the back to mobilize secretion from the lungs. The Acapella's innovative 'rocking' mechanism allows the patient to remove the lung secretion independently, without the help of another person."

The device is considered to be easier to tolerate than other CPT systems, takes less than half the time of conventional CPT sessions, and facilitates opening of airways in patients. There are two varieties to help customize a patient's treatment based on clinical needs, and each device is easily adjustable in terms of frequency and flow resistance by turning an adjustment dial. The device can be used in virtually any spatial orientation. Patients are free to sit, stand, or recline, according to the firm.

The entire product is made using an injection molding process. The impact-resistant device is composed of two primary acrylic plastic materials: glass-filled polypropylene and K-Resin styrene butadiene copolymer. The material selection process was principally based on the manufacturer's key objectives for the product. The material used for the interior components is rigid enough to meet the designers' specified dimensional and density requirements. The manufacturer also wanted the patient to feel comfortable holding and operating the device, so the designers developed a grip-texture for the product. This empowers the patient to feel in control and confident while using the device.

Initially, DHD's key objectives were to develop a vibratory PEP therapy system that functioned independently of gravity controls and met the needs of patients with low-pressure and low-flow constraints. Acapella successfully accomplished both of these objectives and has surpassed projected sales expectations this year.

The manufacturer challenged the design team to develop a device that met the needs of patients with severe respiratory problems, which required the device to be activated at flow rates as low as 5 L/min. The project engineers' solution was a "rocker" system in which a tiny magnet is used to stimulate the vibration needed to mobilize pulmonary sucretions.

Says Beirne, "They placed the system into two different models, one that functioned at flow rates less than 15 L/min and the other at flow rates greater than 15 L/min. Both products have a dial, which allows the user to adjust the resistance and frequency of vibrations to meet their individual needs." Beirne adds that "the product design ensured that patients could receive treatment in any position without the constraints of gravity."

The device is versatile enough to accommodate the needs of lung-disease patients with varying degrees of severity; it can be used with a standard mouthpiece or a mask. It can also be used with a TheraPEP pressure port and gauge for precise pressure measurements, if visual feedback is desired. Finally, it contains a one-way inspiratory valve that enables the patient to inhale and exhale without removing the product from his or her mouth.

"Our firm and DHD Healthcare worked as an integrated team to reduce the product's time to market," says Chloe C. Beirne, marketing specialist with Product Genesis. "The product's functionality was also perfected to ensure that it would be well received in the marketplace." Beirne explains that the device's "soft curves, roundness, colorful appearance, and lightweight body are all intended to communicate a nonthreatening, friendly experience for the patient. The designers were able to incorporate these characteristics in the device's design with the plastics used in the manufacturing process."


GOLD WINNER

Rapid Prototyping Facilitated Device Design

Protectiv Acuvance IV safety catheter
Submitted and manufactured by Ethicon Endo-Surgery Vascular Access (Cincinnati), a Johnson & Johnson company

For more than a dozen years, healthcare providers have attempted to address the problem of accidental needlesticks and the resulting exposure of workers to bloodborne diseases. Universal precautions guidelines and OSHA regulations addressed certain elements of the problem, and device manufacturers attempted to develop safer needle designs and sharps containers that offered greater security.

Most of these products, however, have required users to perform specific actions to ensure their safe use —often so complex that workers must undergo training in use of the device. More recently, manufacturers have attempted to create vascular access products that incorporate passive safety technologies—mechanisms that help safeguard workers without the need for special training or additional procedures.

The Protectiv Acuvance IV safety catheter is a sterile, nonpyrogenic, nontoxic, single-use IV catheter device with a safety feature for insertion into a vein and for the administration of medically prescribed fluids. The device has unique design and engineering features: it offers protection against accidental needle-stick injuries, is the first totally passive safety IV catheter, is intuitive to users, and requires little or no training.

The Protectiv Acuvance device is almost the same size as conventional IV catheters. Moreover, the device has a unique needle-holder design to facilitate handling during insertion and threading into the vein. The insertion procedures for the device are identical to those for conventional catheters; there are no changes in insertion technique. The manufacturer notes that, in addition, the hub and safety mechanism design enable the device to be redirected to access the vein if needed. Once the introducer is removed, however, the needle becomes blunt.

The company notes that the main benefit of using the Protectiv Acuvance IV safety catheter is the reduction of needle-stick injuries, protecting healthcare professionals against bloodborne pathogens. In a study conducted in January 1999, a total of 500 device samples were evaluated by 50 clinicians under simulated clinical conditions. The results indicated that there were no safety mechanism failures or needle-stick injuries. The clinicians also commented that the devices were easy to use and rated them as "highly acceptable."

According to Joseph J. Chang, PhD, director of technology at Ethicon Endo-Surgery, "Significant efforts were made in the initial design stage to address customer requirements through a quality function deployment process and manufacturability requirements through design for manufacturability activities. Moreover, the design and development of the Protectiv Acuvance IV safety catheter used state-of-the-art rapid prototype technology for fabricating and critiquing the prototypes." Chang adds, "These tasks significantly reduced the time required to finalize, verify, and validate the design and manufacturing process for speed to market."

In discussing the award-winning product, the MDEA jurors noted that the catheter design represents "a significant improvement over current technology." They added that the key element is that the safety-related feature functions automatically—without the need for intervention by the user, and with no additional operational steps or user training.

SUPPLIER FILE: BioPlexus Inc. (Tolland, CT)


General Hospital Devices and Therapeutic Products

SILVER WINNERS

Simplifying Bone Marrow Sampling

Goldenberg Snarecoil needle
Submitted and manufactured by Ranfac Corp. (Avon, MA)

Collection of bone marrow specimens is necessary to aid in the diagnosis and treatment planning for patients suffering from various blood disorders such as leukemia, Hodgkin's disease, hypoplasia, and myeloma.

The Goldenberg Snarecoil needle is a sterile, disposable, single-use device that is intended to provide certain benefits to patients and advantages for clinicians when used to obtain bone marrow specimens. Typically, this device would be used by a physician in an outpatient setting with the patient under local anesthesia.

Basically, the Goldenberg Snarecoil needle consists of two major sections, the handle (proximal) and the needle (distal). The handle is constructed of injection-molded polycarbonate components. The needle is constructed of stainless-steel tubing (cannulae) and wire (stylet) that has been cut, welded, and sharpened. The inner cannula incorporates a snare that has been laser cut. These sections are bonded by a thermal pressing process. The completed device is packaged in a Tyvek pouch and sterilized with EtO.

This innovative instrument features an inner snare mechanism that allows the physician to capture the bone marrow specimen after insertion with the simple movement of its lever. Because the physician does not need to be concerned with severing, distorting, or losing the bone marrow specimen, the Goldenberg Snarecoil can be removed from the patient with a minimal amount of force.

Because the needle does not need to be twisted to sever the sample, the need for additional collection passes will be reduced, the firm suggests, resulting in a considerable reduction in patient pain and anxiety. Moreover, there is a significantly higher bone marrow specimen-retrieval rate. Finally, pathological interpretation is improved because the specimens are longer and less distorted, according to the manufacturer.

Challenging History

Grab 'n Go III portable medical oxygen system
Submitted by Praxair Inc. (Danbury, CT); manufactured by Western Medica, a Scott Fetzer company (Westlake, OH)

Oftentimes, new technologies meet daunting hurdles of conventionality. Says Praxair's Andrea J. Nicoll, "An opportunity was seen to provide this simplified device to eliminate age-old problems associated with supplying transport oxygen within hospitals." In the past, to provide oxygen for patient transport or mobility in a timely manner, a separate regulator, flowmeter, cylinder wrench, and washer were required. Intended for use by nurses and other healthcare practitioners, the new system is designed to simplify the administration of portable medical oxygen while improving user safety through the elimination of exposure to high-pressure gas connections.

The Grab 'n Go III portable system simplifies medical oxygen use by combining an oxygen cylinder with a regulator and built-in content gauge. Locating these parts and fitting them together properly had been time-consuming. The oxygen regulator and pressure gauge are are now permanently attached to the gas cylinder as a single, integrated unit.

Not only does the integrated design of the Grab 'n Go III oxygen system provide value through ease of use and safety, it also reduces overall cost to the end-user and practitioner, according to the developers.

The system did pose a number of design challenges, according to Praxair's Nicoll. "The critical and most difficult phase of this project was market acceptance. We were challenging 50 years of history that we learned would not easily be overcome."

SUPPLIERS FILE: Lewellyn Design Inc. (Wooster, OH)


Implant and Tissue-Replacement Products

SILVER WINNERS

Performing a Mechanical Ballet

HELEX septal occluder
Submitted and manufactured by W. L. Gore and Associates (Flagstaff, AZ)

In simple terms, the HELEX septal occluder is a permanently implanted prosthesis indicated for transcatheter closure of atrial septal defects. Pediatric and adult interventional cardiologists use the device as a minimally invasive alternative to open-heart surgery. According to MDEA juror Michael Wiklund, however, "the task of threading the device through the hole, then releasing a spiraling mechanism to seal the hole is a mechanical ballet."

The HELEX is composed of an implantable septal occluder, premounted on a delivery system. The delivery system incorporates a preshaped catheter supplied with radiopaque markers for fluoroscopic visualization during deployment. The basis for the occluder design is a helically shaped wire frame that is elongated to an approximately linear configuration for loading and deployment. The wire frame provides perimeter support for the circular device.

A leaflet that is attached to the support frame and gathered about the center acts to occlude the defect and encourage rapid in-growth of new tissue. An integral locking feature holds the opposing disks together by capturing the three integral eyelets of the support frame. After the device has been deployed, it forms a seal on each side of the atrial defect and the lock encourages each disk to follow the anatomical shape of the atrial septum.

According to Ed Shaw, of W. L Gore and Associates, "The most significant challenge was to incorporate the ability to reposition or retrieve the device in the event of a suboptimal placement. That requirement drove the design of the device and delivery system."

Says Ed Shaw, of W. L Gore, "The strength of the product is its elegant simplicity. The form and function are well suited to the application as emphasized by the common phrase: 'why didn't I think of that.'"

An Elegant Solution for the Hearing Impaired

Nucleus 24 Contour
Submitted and manufactured by Cochlear Ltd. (Sydney, Australia)

The Nucleus 24 Contour is a cochlear implant with an electrode array that safely places 22 stimulating electrodes adjacent to the inner wall of the cochlea without the use of invasive bands or positioners. The system is designed to provide useful hearing to people with severe to profound hearing loss.

The implant operates by receiving sound encoded in a radio-frequency link, sent from a speech processor that is worn externally. Next, the implant decodes the information into electrical impulses that activate any of the 22 electrodes on the array to stimulate the underlying nerve cells. The resulting patterns of stimulation are perceived as sound and speech by the user.

"The important aspect of the design of the electrode and delivery system," says Herbert Voigt, MDEA juror, "was the attention to the problem of getting a charge flow at one electrode site to a restricted region of the cochlea." Voigt believes that it is vital if you want to have independent channels of information delivered to the auditory nerves to get the electrode sites as close as possible to those nerve fibers. This has to be done after winding the electrode array through several coils of the snail-shaped cochlea. He adds, "This was a complex design solution that appears to address the major problems confronting cochlear electrode design and insertion."

Peter Gibson, senior project manager for Cochlear Ltd., notes, "One of the great strengths of the Contour electrode is that it is a platform for a wide variety of future enhancements that are currently being pursued by the design team. One such exciting avenue for enhancement is the use of the lumen as a passage for drug delivery."

"The design goals were well known from the start—safety, performance, and ease of surgery," says Peter Gibson, Cochlear's senior project manager. "It is an elegant solution that works."

Go to the second half of this article

Copyright ©2001 Medical Device & Diagnostic Industry

Automated Tool Prepares Sample Slides for Hospital and Research Labs

Originally Published MDDI June 2001

Note: This is the second part of a two-part article detailing the winners of the 2000 Medical Design Excellence Awards. If you haven't done so, you might like to read the first part of this article.

In Vitro Diagnostics

GOLD WINNER

BenchMark automated histology staining system
Submitted and manufactured by Ventana Medical Systems Inc. (Tucson, AZ)

The BenchMark automated staining system is a modular device that fully automates the staining of tissue samples on glass microscope slides. It is the first histology instrument to automate the labor-intensive steps required in baking, dewaxing, cell conditioning, and staining tissue for the purpose of cancer and infectious-disease diagnosis, according to Ventana Medical Systems.

The instrument is used in the pathology department of hospitals and reference labs by laboratory technicians. The slides are processed with various reagents that remove embedded paraffin, pretreat tissue to expose targets, and bind and detect specific antigens or DNA and RNA sequences with a localized color change or fluorescence. These stained slides are then reviewed under a microscope by a pathologist to determine the diagnosis.

Developing the system required that a number of design challenges be overcome, says Peter Riefenhauser, Ventana's worldwide marketing manager. "The ability to individually control the temperature of each slide on a rotating carousel, and selectably provide seven bulk fluids to the slides was challenging," Riefenhauser states. "Tightly controlling and maintaining the liquid volume on each slide in a range from 25 ml to 700 ml was a challenge that not only involved the design of instrument hardware and control systems, but also included the formulation of reagents."

The BenchMark provides the ability to individually control the temperature of each slide on a rotating carousel, called the Thermoflex platform. This allows for flexibility in staining and run protocols. A creative technique for achieving very low residual slide volumes was developed in response to customer feedback. The Jet Wash or Jet Drain (patent pending) involves a stream of fluid directed at the edge of a slide that draws fluid off the slide without damaging or drying out the tissue, leaving a very low, evenly distributed volume.

To control evaporation, the BenchMark uses a patented liquid coverslip, forming a liquid shield that floats on top of the aqueous solution on the slide, and helping to control evaporation and temperature stability. To mix reagents with the aqueous volume on the slide, BenchMark uses patented vortex mixing, in which gentle, carefully positioned streams of air encourage mixing on the slide without physically touching or disturbing the patient sample.

The product design was intended to give users the ability to control multiple instruments of different types through a single user interface. Combined with bar code reading of patient samples and reagents, this interface enables the user to perform more-complicated multiple runs than was previously possible, according to the company.

The BenchMark "represents a major breakthrough in the application of design-for-manufacture principles," the company indicates. Manufacturing representatives were involved throughout the design process to give insight on areas of improvement. Great effort was put into component utilization from other Ventana instrument lines. Many of the assemblies are designed in such a way that they can only be put together one way to avoid assembly mistakes.

In order to further eliminate manufacturing errors and reduce tolerance stack-up issues, the majority of the BenchMark staining module is built up from a single, solid datum plane. Precision-machined posts extend from this common plane for accurate positioning and ease of assembly. The firmware built into the BenchMark instrument has self-test capabilities. This intelligence creates additional troubleshooting and diagnostic capabilities, helping the assembly and field technicians that work with the instrument.

This instrument line also marks the first product that Ventana completely developed in a virtual environment before building physical prototypes. Using state-of-the-art computer-aided engineering and electronic design automation tools, the product was modeled, analyzed, and modified multiple times before drawings for prototyping were generated. These powerful design tools provided the design team with the capability to test various design solutions and mathematically perform structural and heat-transfer analysis to compare different designs.

"The key achievement of this system is its ability to automate processes that were potentially hazardous, labor intensive, and inherently variable in their outcome," says Peter Riefenhauser, Ventana Medical Systems worldwide marketing manager. "There is no single design feature that provides this; rather it is the integration of the hardware, control, and reagent systems that achieves this," he adds.

SILVER WINNER

Web-Enabled Drug Screening Helps Eliminate Errors

eScreen drugs-of-abuse testing system
Submitted and manufactured by eScreen Inc. (Overland Park, KS)

The eScreen system is a Web-enabled workstation designed exclusively for drugs-of-abuse screening and data management. The system consists of a specimen cup and smart lid (eCup) and an optical Internet appliance (eReader) that scans, reads, and transmits results confidentially to a remote customer.

The eScreen system is designed to remove the five barriers to point-of-care testing for drugs of abuse: aliquot sampling of a forensic specimen, timing and monitoring of assay, interpretation, transcription, and confidentiality. According to John Goodin, senior vice president of engineering and product development with eScreen Inc., "eScreen established a major design criteria that stipulated that the eCup was a 'dumb cup' accompanied by a 'smart lid'." He adds, "The development of the eReader and its optical image recognition software package (i.e., is it a line or isn't it a line?) evolved, over time, into a very sophisticated program."

According to the firm, the eCup is unique in the field of employment drug screening because the donor never comes into contact with the testing device. The cup is simply a specimen container that is used only for collecting the sample from the donor. The eCup smart lid contains the assay strips that perform the five-panel drugs-of-abuse screening function.

Says Goodin, "The primary achievement of the system is speed. Prior to the introduction of the eScreen cup and reader, the quickest turn-around time (under ideal conditions) for a laboratory based pre-employment drugs of abuse test was 36 hours—more often 48 hours. The eScreen system delivers the 95% negative component of pre-employment drug screen test results in one hour."

SUPPLIER FILE: Compression/Moll Industries Inc. (Lake Forest, CA)


Over-The-Counter and Self-Care Products

SILVER WINNER

Providing an Alternative to Self-Catheterization

TravelMate
Submitted and manufactured by Caring Hands Inc. (Hayden, ID)

The TravelMate noninvasive female urinary device faced a number of challenges during its 18-month development cycle. "Experts in the CAD/mold-making profession said the design, as we wanted it, was not manufacturable. Five mold makers turned down the job as being too complex," explains Charles Robertson, principal designer of the device. "Eventually we found a talented team of mold makers who finished the mold, and they did a great job."

The device offers many of the advantages of external urinary catheters, without the problem of uncomfortable methods of attachment. Its noninvasive nature reduces the risk of urinary-tract infection.

The TravelMate consists of one piece of polyethylene that easily bends to conform to variations in the shape of the area surrounding the urethral orifice. The principal design challenge for this noninvasive device was to determine a way to achieve a comfortable leak-free seal between the device and the body while simultaneously keeping it small enough so that it could be easily positioned for use while sitting in a chair or standing with a minimal amount of undressing.

According to MDEA juror Krista Coleman, "The device provides a much-needed solution for women and will provide a definite benefit to many."

Says Robertson, "Our goal was to make a classic design that would be around for many years."He adds that "the project wouldn't have happened without some very talented people and the feedback from hundreds of prototype testers around the world."

SUPPLIER FILE: JB Engineering Inc. (Spokane, WA)


Radiological and Electromechanical Devices

GOLD WINNER

Seeking High Visibility

Echo-Coat ultrasound needles
Submitted and manufactured by STS Biopolymers Inc. (Henrietta, NY)

This innovative product caught my eye because of the huge potential for improving the sampling precision for a wide variety of tissues. To provide the pathologists with the appropriate sample will undoubtedly increase the accuracy of diagnostics and decrease false-negative errors," says MDEA juror Krista Coleman.

Fellow juror Eliot S. Lazar adds, "the coating also strikes me as extraordinarily helpful to the end-user in order to locate a needle tip more readily when performing an ultrasonically guided procedure. Heretofore, needles have been difficult to identify, and with this coating the practitioner can more easily and adeptly carry out a successful procedure because of the ability to see the needle tip."

Echo-Coat ultrasound needles are coated to render the entire shaft highly visible during ultrasound imaging. The needles are used under ultrasound guidance to perform aspirations, biopsies, localizations, or amniocentesis procedures. Physicians in radiology private practice or in hospital settings use these needles to accurately obtain cytology and histopathology samples or to facilitate surgical procedures.

The coating is a layered polyurethane material that is applied to Type 304 stainless steel (i.e., a needle cannula). It has a porous microstructure that entraps microbubbles of air to enhance the echogenicity regardless of the needle angle relative to the ultrasound beam.

Under ultrasound imaging, a standard needle must be held perpendicular to the ultrasound beam to be visible. At nonorthoganol angles, the sound waves are reflected off the needle shaft at angles that do not reach the transducer face. As a result, the needle is not visible. With Echo-Coat ultrasound coating, the trapped microbubbles of air reflect sound waves back to the transducer—even when the needle is at a very steep angle in relation to the transducer. These reflections enable the needle to be clearly visible along its entire shaft.

New applications for the coating technology are continuing to be developed, says Susan Stalls, STS Biopolymers product manager. She explains, "We started with fine needles for aspiration and recently added breast localization needles. We plan to add core biopsy needles later in the summer and then expand further in the fall."

According to Susan Stalls, product manager for STS Biopolymers, developing Echo-Coat ultrasound needles required "almost 10 years from concept to market. In part, this was because it was done entirely by in-house research and development." Stalls adds, "We approached the lack of visibility of medical devices under ultrasound from a totally different angle. Historically, people had tried to change the surface of the metal by dimpling or roughening it. We approached it from 'what is the most echogenic biocompatible material?' Air is great. Now how do we get air onto a device—that's where our coating expertise married our knowledge of ultrasound contract agents, and we began to develop a coating to go over the needle surface to accomplish echogenicity."

SILVER WINNERS

Listening to Customers Provides Key to Improved Device Design

DirectView CR800 system
Submitted and manufactured by Eastman Kodak Co. (Rochester, NY)

The Kodak DirectView CR800 System is a computed radiography medical x-ray image-capture and image-processing system that uses current x-ray exam-room exposure sources and cassette-based techniques while delivering the advantages of digital technology. With an easy-to-use graphical user interface and high image quality, the DirectView CR800 system facilitates wide electronic distribution of x-ray images to radiologists responsible for diagnostic analysis, to referring physicians for review in preparation for treatments and therapies, and to electronic archives where images can be stored for future reference.

Typical imaging applications include chest x-rays for the detection of heart and lung diseases, bone x-rays for fractured bones or bony tumors, and soft-tissue images such as the kidneys and gastrointestinal system. The DirectView CR800 system, in conjunction with the Kodak DirectView remote operations panel, is designed to allow multiple user stations to be placed throughout the imaging environment, resulting in improved workflow, enhanced patient care, and reduced costs.

Dennis E. Sneddon of Kodak explains that reliability and maintaining a small footprint were primary concerns of the development team. "High reliability was addressed by using modeling and continuous reliability testing of critical subsystems during the design process. The subsystem testing identified issues prior to the final designs, and provided an opportunity to address and resolve issues prior to manufacturing."

Sneddon adds that internal Kodak shops played a key role in the concept, design and production phases, and early reliability testing and verification allowed the team to make changes as needed during the process to improve the various subsystems. He explains that "the device's footprint, the customer interface, and workflow were verified by 'voice of customer' processes and user contacts."

Says Sneddon, "The company's industrial design department was instrumental in quickly turning concepts into prototypes, and prototypes into finished equipment mock-ups. Prototyping played a key role in the speed at which design variations were tested and evaluated."

Throughout the project to design and develop the DirectView CR800 system, the engineering team listened carefully to its customers. Hospitals, clinics, and medical imaging centers were looking for new alternatives to digitally acquire radiographic images that would improve x-ray services, increase productivity, reduce costs, and ultimately position their operations favorably against increased competition. Likewise, radiologists and radiologic technologists were seeking ways to enhance workflow, increase patient throughput, improve output quality, and facilitate better overall image management.

One of the challenges Kodak's engineering team faced in developing the system was that of producing a digital high-quality image-capture system that could enable decentralized placement of devices within medical diagnostic imaging areas. Usability scenarios that defined the physical and functional requirements for the system and the user interface were key to the effort. By thoroughly defining parameters in advance, the Kodak design team was able to effectively develop and deliver a fully tooled and tested product within the constraints and boundaries of an extraordinarily aggressive project timeline.

SUPPLIER FILE: Elcan Optical Technologies, a Raytheon corporation (Midland, ON, Canada), Mercury Aircraft (Hammondsport, NY), Gillette Machine and Tool Company Inc. (Rochester, NY), Solectron Technology Inc. (Charlotte, NC), IBM Corp. (Rochester, NY), Micro Industries (Centerville, OH), Kaman Industrial Technologies Corp. (Rochester, NY), Thompson Industries (Port Washington, NY), AJL Manufacturing Inc. (Rochester, NY), Badge Machine Products Inc. (Canandaigua, NY), K&H Precision Products (Honeoye Falls, NY), Noma Appliance and Electric (Tillsonburg, ON, Canada), Delta Electronics Inc. (Research Triangle Park, NC)

According to Kodak's Dennis E. Sneddon, "Our design team had several overarching goals as we designed the CR 800 including: The need for high reliability, small footprint (everything in one box), and design of a customer interface that focused on enhancing workflow."

Using Vascular Brachytherapy to Prevent Restenosis Following Angioplasty

Beta-Cath
Submitted and manufactured by Novoste Corp. (Norcross, GA)

In-stent restenosis is a common problem associated with angioplasty procedures, and often requires coronary-artery-bypass surgery. The Novoste Beta-Cath system can be used by the interventional cardiologist and radiation oncologist in the cardiac catheterization laboratory, and is designed to deliver a prescribed dose of beta radiation to the coronary artery vessel wall.

Tom Weldon, chairman of Novoste, notes that the Beta-Cath design had to overcome two challenges. "One is, it's basically a hydraulic system. Because the device had some electrical components, it presented a real design challenge to keep the fluid hydraulic systems separate from the electrical systems in a handheld device that would operate reliably. An additional challenge was developing the appropriate isotope in a sealed source container in a size with the level of intensity necessary to provide the therapeutic dose targets that we had for the device."

Weldon says the device is distinguished by its novel use of hydraulics "and the associated use of a seed train, which is literally like a bunch of cars parked one end to the other." He suggests that isotope selection for the device provides an additional advantage. "We chose an isotope a with a very long half-life— strontium-90—so the seed train can be reused many, many times, spreading the device cost over hundreds of patients."

SUPPLIER FILE: The Innovation Factory (Norcross, GA), Plexus (Bothell, WA), BeBig (Berlin), and Colorado MedTech (Boulder, CO)


Rehabilitation and Assistive-Technology Products

GOLD WINNER

Prototype Evaluation Offers Key to Prosthesis Development

Pathfinder prosthetic foot
Submitted and manufactured by Ohio Willow Wood Co. (Mt. Sterling, OH)

Among the principal challenges faced by the developers of the Pathfinder prosthetic foot was the need to simulate human gait with natural ankle motion, says Jeff Doddroe of Ohio Willow Wood. The award-winning version of the device included a number of significant engineering and design accomplishments. Doddroe explains that "composite materials used in the toe springs and the foot plate needed to have increased flexibility . . . without sacrificing strength."

Another advantage, Doddroe adds, is the use of adjustability features that enable the unit to be customized for a wide range of users. These features include an adjustable heel, anterior and posterior slides, rotation adjustment, and five toe spring resistances.

According to MDEA juror Michael Wiklund, among the winning qualities of the Pathfinder is the fact that it not only simulates normal gait, but provides a degree of versatility to the user. He states, "When you consider the nuances of designing an artifical foot that will function effectively in many different use scenarios, ranging from climbing stairs to running to standing in place, it emerges as quite an accomplishment. It is even more significant when when you consider that companies have been trying to design good ones for decades—centuries, really. When you consider how much the product will contribute to the quality of life for the recipient, you have the makings of a truly deserving award winner."

MDEA juror Krista Coleman adds, "The improvement over previous designs for the foot and ankle is incredible. They managed to improve several areas that have been problematic for patients and prosthetists." She adds, "Another advantage is the conservation of energy for the user owing to the capability to temporarily store some energy in the springs during early loading of the prosthetic device, and to return that energy to the user later during the phase of gait where the toes are pushing the body forward."

The Pathfinder prosthetic foot can be used by lower- extremity amputees who have moderate to high activity level, a body weight of less than 250 lb, a foot size ranging from 23 to 31 cm, and 9 in. of clearance from the distal end of their limb to the floor. The device's shock absorption, energy-storing capacity, and unique ankle motion work together to provide a greater range of controlled motion to the user, resulting in greater comfort, less fatigue, and improved balance. The Pathfinder is designed for use in the normal environment of an active lower-extremity amputee.

The current generation of the prosthesis evolved through a lengthy evaluation of several prototypes. Doddroe explains, "The most significant contribution made outside [the company] was by the amputees involved in the field testing of the Pathfinder." The objective was to develop a product that would offer improved energy storage and return, shock absorption, increased stability, range of motion, and a smooth transition from heel strike to toe off. The result was a triangular design, a closed shape with three main sides.

Conventional prosthetic feet are based on a cantilever design with a single side and a single joint. The three sides of the Pathfinder triangle—the pneumatic heel spring, the composite toe springs, and the composite foot plate—are connected at three main joints: the toe connectors, the heel connector, and the proximal connector. The triangular concept of the Pathfinder is considered to be advantageous because each side can function as an independent energy-storing component. The connecting joints at both ends limit the deflection of each side, resulting in greater flexibility than a cantilevered design, the firm indicates. Increasing the flexibility of the elastic components enhances their ability to store energy, producing a greater dynamic response. The Pathfinder's triangular design enables each side to act synergistically with the others to provide an optimal gait.

The product design also provides a "polycentric ankle motion" that enables the device to exhibit a complex motion "that users claim to be much like a natural ankle," according to Ohio Willow Wood. The result is that amputees experience smoother foot motion and a more natural feel. The foot is also more stable and provides better balance for amputees, the company adds.

According to the manufacturer, the Pathfinder enabled the company to enter a segment of the prosthesis market where it had not previously been a competitor. There are also several production features of the Pathfinder that can be incoporated into existing product lines at Ohio Willow Wood, which will enhance performance of those products. This design also reaffirms the company's commitment to providing new and improved technology in the prosthetics industry and offering freedom of motion to amputees.

Approval and coding from several governing bodies within the orthotic and prosthetic industry is still pending. While the company has had several independent Veterans Administration (VA) offices approve individual purchases of the Pathfinder by veterans, it is still awaiting final approval by the VA. The Pathfinder has passed all applicable ISO structural tests. Doddroe notes that the company intends to enhance the next generation of Pathfinder to increase its weight limit from 250 to 350 lb.

SILVER WINNERS

Hearing Aid Uses Digital Perception Processing

Claro and WatchPilot digital hearing instruments
Submitted and manufactured by Phonak (Warrenville, IL)

Hearing aid development has already attained two different goals: devices have been made smaller, and communication in background noise has been improved. "Today we want to make it easier to hear and understand speech in quiet places, noisy places, and anywhere the wearer wants to hear," says Laura Voll of Phonak AG. "We also want the sound quality to be as natural as possible and control over the hearing aid as convenient as possible."

Claro is a digital hearing instrument that can be used in all environments. Claro uses two unique technologies for reducing background noise. The WatchPilot is a first-of-its kind remote control contained in a wristwatch, according to Phonak.

One of the technologies used in Claro to reduce background noise is adaptive digital AudioZoom. AudioZoom is the first hearing-aid system that uses two microphones to create a directional response. Conversation from the front is increased, while sounds from the sides and back (background noise) are effectively reduced.

Claro employs digital perception processing, a method that uses 20 overlapping and interdependent channels to process sound just like the normal human ear. Contained in its microprocessor is a computer model of the normal ear.

The biggest challenge for any hearing instrument is to effectively reduce background noise. Claro uses two unique technologies to do this, fine-scale noise cancellation (FNC) and adaptive digital AudioZoom (dAZ). FNC scans the signal in each channel and identifies speech relative to steady-state noises. It increases the speech signal and reduces the noise as much as possible. The manufacturer states that the dAZ uses a two-microphone array system to reduce the sound coming from other directions and improve reception of conversational speech.

Says Voll, "There have already been enhancements in the system." She explains, "One of the advantages of offering digital signal processing that is controlled using a personal computer is that upgrades occur through software, rather than hardware."

Simplifying Personal Oxygen Use

HELiOS personal oxygen system
Submitted and manufactured by Tyco Healthcare Puritan-Bennett (Indianapolis)

HELiOS, which stands for high-efficiency liquid-oxygen system, is designed to provide chronic obstructive pulmonary disease patients with their prescribed oxygen in a home-care environment. The system consists of a reservoir and a portable unit. The reservoir holds up to 46 L of liquid oxygen, and is used to fill the portable unit for ambulatory or mobile use. The portable unit includes an innovative pneumatic 4:1 conserver device, "which allows for the best combination of duration, small size, and light weight—3.5 lb when full," according to the manufacturer. Together, the two units provide a home oxygen system "that can effectively be 'worn' rather than 'lugged around,' which promotes patient mobility and allows for better patient prescription compliance," say Lee S. Toma, senior engineer with Puritan Bennett.

Toma notes that the system's biggest achievement was creation of the oxygen conserver. "Powered by the pressure of the oxygen gas," he explains, "it eliminates the need for a heavy and unreliable battery. Based loosely on our previous design, which only delivered oxygen on inhalation and saved about 50% over a standard continuous flow prescription, the new design saves about 75% by using a new algorithm evaluated in clinical tests." Says Toma, "This allows a very small unit to hold enough liquid to last up to ten hours at the most common 2 liter-per-minute setting. It also allows the homecare provider to save time and money on liquid deliveries."

"The main development challenge of the project was to create a system that would appeal to users based on ergonomics and style, while also making the system economically viable for the homecare providers," says Lee S. Toma.

SUPPLIERS FILE: Omnica Corp. (Irvine, CA)


Surgical Equipment, Instruments, and Supplies

Light-Activated System Assists Rapid Sealing of Sutures

Tissuebond applicator and Tissuemed 180 light source system
Submitted by DCA Design Consultants (Warwick, UK); manufactured by Tissuemed Ltd. (Leeds, UK)

The Tissuebond system consists of two main components, a custom-designed applicator and a light source for activating the Tissuebond sealant. The disposable applicator is similar in size and shape to a pen and contains the Tissuebond sealant. Composed of porcine albumin, glycerol, and water for injection, the sealant also contains methylene blue to give the sealant a distinctive blue color. This enables the surgeon to see exactly where the sealant has been applied. It also acts as the chromophore, or switch, which activates the bonding process when a special light is applied to the Tissuebond material.

The main applications of Tissuebond are to act as a tissue sealant and to aid anastomosis. The single-use Tissuebond applicator is designed to deliver a precise amount of sealant during surgical procedures. A finger-controlled lever on the applicator enables the user to dispense an accurately controlled bead of adhesive onto the area of tissue requiring bonding. Tissuebond will be used in surgical procedures where blood loss and time to obtain clotting should be kept to a minimum. Often this will be in cardiovascular surgery procedures where surgeons have to join two ends of blood vessels together to bypass blockages in the vessel. It will also be used to join human vessels with manufactured vessel-grafting materials such as Dacron and PTFE.

According to DCA Design Consultants, "The design process for the applicator involved a detailed study of surgeons' needs and current practices. Then, having identified a range of design concepts, DCA constructed working models and rigs to determine the optimum ergonomic solution. DCA also liaised closely with a specialist mold maker to optimize the design of the components to suit high-volume manufacture." The design firm adds, "In complete contrast to the applicator, the lightsource is designed for low-volume manufacture and therefore uses processes such as RIM casting, CNC machining, and metal fabrications using laser-profiled blanks."

The Tissuemed 180 light source system delivers a cold, filtered light beam through a handheld wand that is directed at the area where Tissuebond has been applied. The surgeon controls the beam by pressing a foot switch. The methylene blue in Tissuebond absorbs light emitted from the system. Within a few seconds of applying the light source to the Tissuebond, an obvious change of color from blue to clear or light blue gives the surgeon visual confirmation that the sealant has been successfully activated. The light source is used during surgical operations to cure the tissue adhesive at the site of the wound. It is typically used in an operating theater environment. All the components that may contact the patient directly or indirectly are capable of being sterilized.

Tissuebond requires no preparation and can be used directly out of the refrigerator, allowing the surgeon to react to bleeding sites immediately. The rapid sealing of the sutured area forms a strong yet flexible barrier, allowing the natural healing process to begin.

Says DCA, "Tissuemed looked at their own in-house skills and realized that the skills required were outside their own areas of expertise. Secondly, time to market was important and therefore the use of an external agency with large resources and efficient working practices was required."

SILVER WINNERS

Developing a Noninvasive CABG System

Aortic connector system
Submitted by redgroup (Minneapolis); manufactured by St. Jude Medical (St. Paul, MN)

The St. Jude aortic connector system delivers an implanted device designed to create the proximal anastomosis of an aortic autologous vein graft. It is intended to be used as a noninvasive means to cardiac bypass surgery and eliminate the need for hand sewing. Surgeons are the intended primary users.

The implantable device is made of nitinol. The delivery device is constructed of injection-molded ABS, and the release tubes are made of stainless steel.

The primary design problem addressed was loading the system with a vein, then delivering and connecting it successfully to the aorta with accuracy and limited hand movement. The overall shape and geometry of both the aortic cutter and the delivery device were specific to each task they had to perform. Based on user research, the aortic cutter needed to be used both in a syringe and pipette configuration. The aortic delivery device has a pipette configuration, allowing for greater accuracy and reduced hand movement. The button guard was specifically designed to protect the button from accidental deployment, yet allow the surgeon to access the button with minimal finger movement.

According to Lars Runquist, a principal in redgroup, there were several key relationships that were useful in the development process. "The molding vendor played a key role," says Runquist, "helping in tool development in parallel with the design of the product. The result was very few tooling revisions, and a faster program."

Runquist explains that succesfully addressing ergonomic considerations was a key achievement of the design—"how the surgeon handles the device, including both the cutter and the applicator." He adds that efforts to enhance the device are ongoing. "We have already completed additional size variations of the product," he states.

Creating a New Point of View for Surgeons

InsideView
Submitted and manufactured by LSI Solutions (Rochester, NY)

The InsideView medical display system, manufactured by LSI Solutions, uses advanced video-projection technology to display a high-resolution video image on a sterile, disposable screen appropriately positioned within the sterile surgical or interventional procedure field.

"This is a vast technical improvement for practitioners in that they will not need to divert their attention from the procedure to turn and view a screen in some more-distant location," says MDEA juror Eliot S. Lazar. "The benefits are to both the end-user and the patient."

Physicians using this unique visualization technology can operate in a natural and comfortable way because they can simultaneously view the internal operative site and their hands. Communication and teaching are improved during procedures by allowing operators to point to and touch the video image.

According to LSI Solutions, the InsideView medical display system "utilizes advanced video projection technology to display a high-resolution video image on a sterile screen appropriately positioned within the sterile surgical or interventional procedure field." The firm adds, "Physicians using this unique visualization technology can once again operate in a natural and more comfortable way because they can simultaneously view the internal operative site and their hands."

The system also supports communication and teaching efforts during procedures by allowing operators to point to and touch the video image.

LSI suggests that most videoscopic medical procedures can benefit from the system. Example application areas include general surgery and urologic, gynecologic, and cardiac interventions. Endoscopy is another potentially enormous market. Radiologic procedures, especially fluoroscopic procedures for diagnostic and therapeutic interventions, will benefit from application of this technology, the company indicates.

The system video projector is held within a proprietary optical fixture mechanism manufactured by LSI. The EtO-sterilized screen kits are made of high-grade, lightweight optical plastics that are conveniently packaged for cost-effective, single-patient use.

Making the Prospect of a Breast Biopsy Less Intimidating

Mammotome handheld breast biopsy system
Submitted by Plexus Corp. (Neenah, WI) and Herbst LaZar Bell (Chicago); manufactured by Ethicon Endo-Surgery (Cincinnati)

With the incidence of breast cancer on the rise among women of all ages, it has become increasingly important to develop devices that facilitate breast biopsy procedures, explains Cassie McQueeny-Tankard of Herbst LaZar Bell Inc. (HLB). The Mammotome handheld breast biopsy system is a minimally invasive, highly accurate, mobile instrument for helping doctors diagnose breast cancer at the earliest stages while increasing comfort to patients.

The new Mammotome system creates a less-intimidating and more-comfortable arrangement for the patient with minimal procedure preparation time. The procedure may be completed in less than an hour in a doctor's office or on an outpatient basis under a local anesthetic and requires no surgery or stitches. It allows the patient to lie comfortably on her back.

The Mammotome probe is inserted only once into the patient's breast via a small incision. Once inserted and positioned using ultrasonic imaging, the needlelike probe can collect multiple samples by means of vacuum aspiration and an internal rotating cutter. The vacuum draws the sample into the probe aperture within reach of the cutter. From there, tissue samples can be obtained in and around the targeted area. Even though the incision is smaller, these samples can be eight times the weight of samples obtained with traditional spring-loaded biopsy equipment.

According to McQueeny-Tankard, "HLB contributed to the electrical engineering of the onboard microprocessor, which automates the sampling process. Biopsy sampling is no longer manual." She adds that the use of a positioning sensor enables the color touch-screen monitor to reflect the exact position of the cutting tip. "An easy-to-follow graphical user interface was developed to give surgeons maximum control over the location from which the biopsy sample is taken," she states.

The engineering design team created a two-motor cutting drive system self-contained in the base unit and connected to a lightweight handpiece that eliminated the need to table mount the cutter assembly. Lightweight, flexible cables connect the base to the disposable handpiece, which is lighter and easier to control than its predecessor. This handheld unit, which incorporates cutter position sensors, allows physicians to place the sampling probe accurately and obtain larger samples of suspect tissue.

"The cutting drive system was also redesigned to include the new Smart Cutter, a unique feature that provides direct feedback control of both cutter translational and rotational speeds," says McQueeny-Tankard. "When either the translational speed or rotational speed is not at the desired rate due to increased or decreased loading on the system, the control feature modifies the power to the motor. This allows the speeds to remain near their desired levels."

In addition, the handheld cutting probe was ergonomically designed to allow for easy manipulation and procedure control through the soft-touch finger-control keypad. Precise position control lets the cutter close the aperture through which the sample enters without bottoming out at the end of the probe. Good position control—within 0.001 in.—enabled the design team to minimize the length of the cushion, or "dead zone," at the end of the probe. Incision of the tissue and completion of the sampling as directed is achieved without causing damage to healthy surrounding tissue.

The technology at the heart of the Mammotome system is the SmartVac computer-controlled vacuum system. According to McQueeny-Tankard, this enables the vacuum to cycle on and off, and optimizes the vacuum in accord with the cutter activity. The vacuum retrieval system allows the caregiver to take multiple samples of a lesion while the needle probe remains in the breast. This second-generation device is able to obtain larger samples than its predecessor. "As a result, there are fewer dry taps, or the inability to obtain an adequately sized sample of the suspect tissue," McQueeny-Tankard indicates.

SUPPLIER FILE: Phillips Plastics (Hudson, WI), MPE Inc. (Milwaukee, WI), Marksman Metals (St. Michael, MN), Innovative Machining (Neenah, WI), Identco (Ingleside, IL), Scotts Models Inc. (Cincinnati), MPI International Inc. (Rochester Hills, MI), Arrk (San Diego), Cut Craft Inc. (Ft. Worth, TX)

Safer Medical Waste Handling

Neptune waste-management systemSubmitted and designed by American Immuno Tech Inc. (AIT; Costa Mesa, CA); manufactured by Bio-Medical Devices Inc. (Costa Mesa, CA) for Stryker Instruments, a division of Stryker Corp. (Kalamazoo, MI)

Management and disposal of fluid and certain airborne medical wastes has posed difficulties for hospitals. The Neptune waste-management system was developed to provide viable waste management alternatives. The system is intended to be used in the operating room, pathology and surgical centers, emergency rooms, and doctors' offices to evacuate, collect, and dispose of hazardous surgical fluid waste as well as to evacuate smoke generated from electrocautery or laser devices.

Says David H. Mills, AIT director of business development, "The technical challenge of moving bloody debris through the system without a clog building up and compromising the surgeon's suction was the biggest obstacle. Secondly, delivering high quality suction without creating excessive noise was also a challenge for the engineering team."

The system consists of two components—a rover and a docking station. The rover is designed to be located in the surgical suite or where the fluid waste or smoke is generated. The docking station is used to collect fluid waste from the rover unit prior to disposal. The device can collect as much as 20 L of fluid at one time, with fluid volume measured electronically, and is accurate to approximately 250 ml. This feature delivers a safer means of monitoring fluid absorption during high-fluid procedures, including transurethral radial prostatectomy or endometrial ablation.

Unique to the Neptune system is the incorporation of multiple products into one common footprint, says Mills. The system combines a traditional suction canister-tree with that of a smoke evacuator, and adds an optional power IV pole to aid in the delivery of irrigation fluid during high-fluid procedures. Equipped with the ability to accurately track the fluid waste collected via a digital display, the rover aids the gynecological surgeon in monitoring fluid absorption.

Copyright ©2001 Medical Device & Diagnostic Industry

Software Options for Automation Equipment Design

Originally Published MDDI June 2001

Automation

The tools a medical device company uses for designing automation equipment can make or break the transition to automation. The key is knowing what's out there.

Kenneth Lindner, Eric P. Kilburg, Roger Hambro, and Charles Conrad

A medical device company's decision to automate can result in a streamlined manufacturing process and a more efficient workplace. Supporting the transition requires significant resources and skills, and the company or its automation partner must have a solid understanding of the available tools to effectively design the necessary automation equipment.

Developing an equipment design within a 3-D solid-modeling environment enables a company to create the most robust design in the shortest schedule time. Since equipment designers typically conceptualize in a 3-D realm, they should convey their ideas to a 3-D medium for the design process. Solid-modeling software is ideal for this. The technology allows the designer to manipulate the model, investigate for design issues, and resolve them in the virtual environment prior to committing the design to manufacturing. This 3-D review makes for a better design, and can be extended well past the designer's desk to multifunctional design reviews across many disciplines. The reviewers can then visualize the equipment and make comments and changes before committing the design to production. Changing the virtual environment is infinitely easier and more cost-effective than having to rework equipment on the manufacturing floor.

Snapshots of the design screens from Pro/Engineer, a 3-D solid-modeling computer-aided drafting (CAD) package from PTC (Needham, MA), showing percent of model processed as it is designed.

There are many competitive 3-D solid-modeling computer-aided drafting (CAD) packages, including Pro/Engineer from PTC (Needham, MA). Pro/Engineer provides a flexible engineering and product development infrastructure. This infrastructure can rapidly respond to changing market conditions in support of company business initiatives such as strategic supplier collaboration, customer-tailored products, market-driven innovation, engineering productivity, digital-product confidence, and knowledge reuse. This software features innovative, next-generation behavioral modeling technology and ease of learning, use, and productivity.

There are other mechanical CAD systems available to designers of medical devices. Products such as I-DEAS from SDRC (Milford, OH), CATIA and SolidWorks from Dassault Systemes (Suresnes, France), UGS and Solid Edge from UGS (Cypress, CA), Thinkdesign from Think3 (Santa Clara, CA), and Inventor from Autodesk (San Rafael, CA) are just a few. They vary from the high-end price range ($10,000–$30,000 per seat) to the mid-range point of approximately $5000 per license.

ANALYSIS AND SIMULATION SOLUTIONS

Analysis technology is a vital component of the software tool kit. Products such as Pro/Mechanica from PTC allow design engineers to quickly and easily address the function, assembly, and design of every part—providing early insight into how a product will perform in the real world. Using the software, engineers can explore various design scenarios and quickly converge them for the optimal design, eliminating a compromise of quality or an overdesigned product. Users can seamlessly download Pro/Engineer models to Pro/Mechanica for analyses.

Fringe plot showing stress, from PTC's Pro/Mechanica analysis software, which allows engineers to address the function, assembly, and design of each part of a product in early stages.

Pro/Mechanica analyses (such as how an assembly will behave in motion) capture product behavior and provide the necessary insight to create the best possible product, all within an easy-to-use environment designed for the engineer unfamiliar with analysis techniques. The software equips design engineers with functional information about the products they are modeling while automating as many of the technical aspects as possible.

Users define loads, constraints, joints, and temperatures directly on the model geometry—allowing concentration on the product rather than on the mathematical abstractions used for analysis. Pro/Mechanica uses precise design geometry without faceted approximations, ensuring more-accurate results. It enables multidiscipline simulation with associative solutions for motion, structural, thermal, and vibration analysis.

VSA-GDT/Pro software, from UGS, is directly integrated with Pro/Engineer through the use of Pro/Toolkit. VSA software uses the geometry, tolerances, and assembly process information directly from Pro/Engineer whenever possible to provide the highest level of integration with the user's product data management system and for ease of use. In order to determine if the tolerance scheme created in Pro/Engineer is correct according to the standards of the American Society of Mechanical Engineers, the American National Standards Institute, and the International Organization for Standardization, VSA-GDT/Pro uses a patented, math-rule base to analyze the tolerance scheme created in Pro/Engineer. The software verifies that each feature is correctly constrained in form, orientation, location, and size. It also ensures that the feature-control frames are syntactically correct and that each feature is related to the master data-reference frame through one unique path.

The best equipment design is not necessarily the best solution unless it is designed in the context of the entire manufacturing process. To make a medical device–manufacturing system successful, the design team needs to evaluate the material and labor flow in the process. There are software tools that can simulate production at the plant level where material, labor, MTBF (mean time between failure) efficiencies, and bottlenecks in the process can be evaluated again before committing the system to production.

Design for Assembly (DFA) from Boothroyd Dewhurst Inc. (Wakefield, RI) is a core software tool for concurrent engineering work. It not only allows users to quantify assembly time and labor costs, but it also challenges users to simplify the structure of products and thereby reduce part and assembly costs. Companies have recorded millions of dollars in savings simply by applying DFA at the early stages of product design.

The assembly time standards included in the software are based on extensive research confirmed by years of industrial usage. They cover wire-harness and printed circuit board assembly, as well as mechanical assembly. There are full-featured, user-editable databases for a company's standard items and special operations. The software has been successfully applied across a broad range of products from disk drives to satellites, and from elevators to analyzers.

Simulation of a plant layout from the AutoMod suite of software from AutoSimulation Inc. (Bountiful, UT). The software is used for design, analysis, and emulation of complex systems.

The AutoMod suite of simulation software from AutoSimulation Inc. (Bountiful, UT) provides tools for design, analysis, and emulation of complex systems. AutoMod combines virtual- reality graphics with a flexible, powerful, discrete, and continuous simulation environment. Templates of commonly used components facilitate quick and accurate modeling of a wide range of systems, such as manufacturing operations, materialhandling systems, tanks and pipe networks, warehousing and distribution centers, transportation and logistics, baggage handling and airport operations, and semiconductor manufacturing.

Simulation using the AutoMod suite allows users to see designs in the virtual world before making costly changes in the real world. A realistic and accurate model helps individuals at all levels of an organization, from management through engineering and production, to see how their operations will work. A model can help users to do the following:

  • Determine the optimal equipment configuration.
  • Decide how much equipment to buy.
  • Troubleshoot an existing system.
  • Identify bottlenecks in the operation.
  • Train on system operations.
  • Communicate changes in the design.
  • Test equipment controls prior to installation using emulation.

Simulation does not have to be at the plant level only. Difficult processes should be simulated to mitigate the risk in a new process. Being able to simulate or animate the motion of the equipment in a new process allows the design team to confirm the feasibility of the process.

Another proven technical tool for simulation is Adept Digital Workcell from Adept Technologies Inc. (San Jose). The software is a powerful 3-D virtual robot and cell simulator that focuses on small-parts assembly and material-handling applications. Using AdeptWindows PC software, users have the ability to program virtual workcells using native AIM and V+ programming codes. The design team can execute programs in real time using the AdeptWindows Controller to drive the virtual robots and cell peripherals.

Software development productivity is greatly increased, since programming and debugging can be done before or during cell assembly. Adept Digital Workcell is integral to facilitating rapid deployment automation by even further reducing the time required to implement robot systems. The Adept Digital Workcell allows organizations to implement concurrent engineering, debug programs in a safe virtual environment, increase programming productivity, and reduce software-development lead times and time to market. In addition, it serves as a valuable training tool.

PDM SOLUTIONS

Probably the most critical software tool for medical device equipment design is the product data management (PDM) software for the various design and simulation tools. PDM systems provide a secure vaulting location for all the designs, as well as a focal point to enable concurrent engineering. Electronic data management ensures that all users are accessing the latest revisions, provides backups, and enables the sharing of data between multiple users and even multiple geographic locations. A PDM system also can fulfill quality system requirements.

PTC offers Pro/Intralink as a work group management solution for product development using Pro/Engineer. It lets Pro/Engineer users facilitate design-team collaboration and manages the power of Pro/Engineer associativity. It provides a dynamic, collaborative environment that supports Pro/Engineer's rapid and effective design approach.

The software manages the relationships between Pro/Engineer deliverables from conception to design and manufacturing. It simplifies the Pro/Engineer data management activities necessary for product development by transparently incorporating them into the design process. Pro/Intralink enables concurrent product design by communicating interrelated changes to the various engineers affected, so they can incorporate design changes and update current information. Simple, process- focused tools capture and execute management tasks so that engineers can concentrate on innovative product design.

The software simplifies the data management activities of engineers so they can be productive. It offers powerful tools to incorporate information management activities directly into the design process. Many such tasks that need to be done in Pro/Engineer can be accomplished faster and more efficiently by using Pro/Intralink. By facilitating design reuse, Pro/Intralink makes effortless the copying and renaming of existing designs and updating of related deliverables, such as drawings.

Pro/Intralink delivers benefits to both the engineering workgroup and the extended enterprise. Using Pro/Intralink Gateway allows engineering information from Pro/Engineer to be shared seamlessly throughout the enterprise, enabling true enterprise-wide collaboration.

Automation can enable a company to improve its performance, but can only be effective if equipment design is supported with the right skills and tools. The medical device manufacturer should give as much thought to the automation design software tools as to the decision whether or not to automate.

WHEN IS THE RIGHT TIME TO AUTOMATE?

There is no universal formula that provides the answer to whether manufacturers should or should not automate. To aid in the decision process, company management may want to weigh the reasons why automation may be desirable:

    • Production capacity is overly constrained.
    • Per-unit cost is too high.
    • Yield is too low.
    • Product quality is off-target.
    • Finding skilled labor is a problem.
    • Operator safety and health are concerns.
    • Material waste is significant.
    • Data collection and tracking are unreliable or burdensome.

Increasing capacity and production rates and decreasing per-unit cost are the historical reasons for implementing automation. Today, other issues such as consistency, material waste, quality, variability, and safety are equally important.

Achievement of these improvements is not guaranteed, however. Implementers need to work towards these improvements, particularly when automating nonstandard processes and difficult-to-handle products. In some cases, manufacturers never achieve the desired improvements, and manual operations turn out to be more cost-effective.

For some companies, automation may not be a suitable solution. Manual operations may be a more viable option when any of the following situations is present:

    • Low volumes.
    • Extensive per-unit customization.
    • Difficulty in automating operations.
    • Capacity, yield, quality, and safety are not pressing concerns.
    • Lack of resources and skills to support automation.

There are many questions an organization should ask before coming to any decisions about automation, including:

    • What are the manufacturing economic metrics?
    • What are current and future production requirements?
    • What are the potential improvements regarding cost, yield, quality, and safety?
    • What are the risks?
    • What are the alternatives?
    • Does the company have the necessary technical expertise?
    • Is there a process that can be automated? Have products been designed for manufacture and assembly?
    • Does the engineering support exist to help evaluate different means of automation?
    • Can the organization support the entire automation cycle—analysis, design, implementation, operation, and maintenance?
    • What is a feasible project schedule? What are the milestones of that schedule?
    • Can the company make the assessment and the decisions?

For many companies struggling to answer the question of whether to automate, it's beneficial to seek an automation partner, especially if the organization lacks the expertise and skills to make the difficult but critical decisions. The partner should be familiar with applicable regulations, directives, and guidances, such as the FDA quality system regulation and/or EU medical device directives. A good partner should be able to provide special technical capabilities such as experimental design, prototyping, testing, and validation. The partner should also have some specific expertise in relevant areas such as biocompatible materials and coatings, medical packaging, or sterilization technologies.

Various scenarios commonly arise in the automation decision process. Two important ones are when existing products will not change and when new products are still evolving. Manufacturers are typically unwilling to make changes to products that are already in production. This is especially true of medical device manufacturers wishing to avoid additional validation costs and delays. They seek automation only for the manufacture of those products. In these cases, the issues that arise and the expertise that the partner requires centers around process automation and equivalency demonstration.

Other times, automation is associated with a new product introduction. The product is still in the design phase, but the manufacturer wants to begin working on the manufacturing process. This is often called concurrent, or simultaneous, engineering and is an ideal opportunity to bring in an automation partner, provided the partner can contribute to both product and process development, and optimize the various design trade-offs. In the case of concurrent engineering, the partner should have product design expertise, specifically medical device product design. The partner should also be able to adapt to evolving projects and make adjustments and document changes as issues develop.

Copyright ©2001 Medical Device & Diagnostic Industry

The Adhesive Bonding of Medical Devices

Originally Published MDDI June 2001

Adhesives

The Adhesive Bonding of Medical Devices

For medical device manufacturers, selecting the right adhesives and developing the correct bonding procedures—including surface preparation, adhesive dispensing, and curing—are critical parameters in the successful use of joining technology.

Mehdi Tavakoli

Joining is one of the key issues in many manufacturing industries, and the medical device industry is no exception. Medical devices are becoming more complex and more sophisticated, both in performance specifications and structural complexity. Whether used outside the body, in the form of instrumentation or surgical tools, or inside the body, for diagnostic monitoring or therapeutic purposes, medical devices typically consist of components and materials that must be joined in some way.

Mechanical fastening is often limited by the joint design and the mechanical and environmental performance it offers. But other joining processes, such as welding, brazing, soldering, or adhesive bonding, can provide technical and economic advantages.1–3

Light curing of a radiation-curable adhesive.

This article provides an introduction to the use of adhesives in the production of medical devices and reviews the main types of adhesives used in medical applications. It explores surface pretreatment, curing and dispensing techniques, and typical adhesive applications in the medical device manufacturing industry.

ADHESIVE CLASSIFICATION

Adhesives may be generally classified in one of six ways, as follows:

  • By chemical type (epoxy, silicone).
  • By origin (natural, synthetic).
  • By physical form (films, tapes, pastes, one- or multipart components).
  • By curing method (e.g., heat curing, moisture curing, radiation curing).
  • By functional type (structural, pressure-sensitive, hot-melt).
  • By end-use function (sensors, catheters, tissue, or bonding).

Thermosets, Thermoplastics, and Elastomers. Polymeric-based adhesives can be divided into three major classes: thermosets, thermoplastics, and elastomers.

A thermosetting adhesive, as the name suggests, becomes set into a given network, normally through the action of a catalyst—heat, radiation, or a combination of these factors—during the process of cross-linking. As the name suggests, cross-linking is the process of forming cross-links between linear polymer molecules (curing is another term commonly used). As a result of this process, thermosets become infusible and insoluble. Thermosetting resins (e.g., epoxies, polyesters, and phenolics) are the basis of many structural adhesives for load-bearing medical applications, as well as for the precision joining of electronic parts.

In contrast, thermoplastic adhesives (e.g., polyamides) are defined as materials that soften, melt, and flow when heat is applied; the adhesives solidify when cooled. Figure 1 provides a simple illustration of thermoplastic and thermosetting polymers.

Adhesives may also be based on natural elastomers (e.g., natural rubber) or synthetic elastomers (e.g., styrene-isoprene-styrene block copolymers). Elastomers (e.g., polyisobutylene) are the main polymers used in pressure-sensitive adhesives for producing medical tapes.

Figure 1. An illustration of the differences between thermoplastic and thermosetting polymers.

Adhesives based on other natural origins (e.g., proteins, cellulose, or starch) are also available and are important for many medical and pharmaceutical applications.

ADHESIVE TYPES

Acrylics. There is a wide range of acrylic-based adhesives that join a variety of similar and dissimilar materials. The main types of acrylic-based adhesives are cyanoacrylates, anaerobics, and modified acrylics.

These adhesives are usually available as solvent-based liquids, emulsions, tapes, or monomer-polymer mixtures (one- or two-part components), with liquid or powder curing agents. Acrylic-based adhesives may be polymerized or cured using moisture, catalysts, heat, ultraviolet (UV) or visible light, or other sources of radiation. These adhesives are of particular interest in the medical industry both for joining medical devices and as tissue-bonding agents. 4–6

A number of medical-grade tapes and films (e.g., single- or double-side coated, woven and nonwoven, elastic, and absorbent materials) are available. They are used in a variety of applications, including allergy patch testing, nicotine patches, ostomy devices, and general dressings. Many of these tapes and films can withstand EtO and gamma sterilization.

Cyanoacrylates, important acrylic adhesives, are commonly known as superglue. The polymerization, or hardening, of cyanoacrylates is initiated by the presence of moisture or of weak bases in the atmosphere or on the substrate. Considerable improvements have been made in using cyanoacrylates as surgical tissue adhesives, but there are limitations in terms of toxicity, strength, durability, and safety.4

Epoxies. Epoxy resins are thermoset adhesives based on the epoxide group (also known as the oxirane group), a three-membered carbon, carbon, and oxygen ring structure:

The ability of this group to undergo a variety of polymerization and cross-linking reactions leads to multiple epoxy resins with a wide range of chemical and physical properties and molecular weights and structures. Epoxies are among the most widely used adhesives for both structural and nonstructural applications.

Epoxies are used in a number of medical devices for bonding and sealing. A clear, medical-grade, low-viscosity epoxy adhesive has proven useful in the fabrication of access ports that are implanted beneath the skin of patients who require multiple infusions.7 By allowing access for subsequent treatments, the access ports enhance patient comfort and have been shown to reduce complications.

When combined with a catheter assembly, access ports can be used to deliver drugs to a particular area of the body. They can be used for arterial, venous, peritoneal, or interspinal access. One example of such a device is based on potting the stainless-steel or titanium access port with an epoxy adhesive or encapsulant. This particular adhesive passed all USP Class VI biological and toxicity tests (i.e., acute systemic and intracutaneous toxicity, implantation tests, and cytotoxicity tests).

Polyurethanes. Medical-grade polyurethanes are used as adhesives, encapsulants, or coatings in many medical devices. Most commercially available polyurethane systems are based on polyethers or polyesters with terminating hydroxyl functional groups. The reaction of an alcohol and an isocyanate results in the formation of a urethane, as follows:

The materials used in most polyurethane systems usually consist of one of several different formulations: di- or polyfunctional alcohols; polyhydroxy compounds (known as polyols); di- or polyfunctional isocyanates; or low-molecular-weight alcohols or amines. A general scheme for the reactions involved in the formation of a polyurethane system is as follows:

Figure 2 shows an example of the polymer coating on a biopsy needle.8

Silicones. Organopolysiloxanes—or silicones, as they are generally known—are semiinorganic-based polymers with a molecular structure comprising alternating silicon and oxygen atoms. Organic side or end groups are attached to some or all of the silicon atoms. The repeating units of these polymers can be shown as follows:

Depending on the nature of side groups and the interchain cross-linking, silicones are available in the form of gels, liquids, or elastomers. The most widely used side groups (R and R') are based on methyl (–CH3), phenyl (–C6H5), vinyl (–CH=CH2), or hydroxyl (–OH). Vinyl and hydroxyl groups are chemically reactive and, in the presence of a suitable curing agent, can be cross-linked.

A simple and general classification of silicone-based adhesives is shown in Figure 3. Unlike an acetoxy cure, which produces acetic acid and can cause corrosion, a neutral cure (with no corrosive by-products) is ideal for medical electronic applications.

Silicones are used as adhesives, coatings, or encapsulants in medical devices. The most important types of silicone used in implants are fluids, gels, and elastomers (rubbers).

An example of implantable-grade silicone is a mixture of pure silicon resin (e.g., di-methyl silicon elastomer) and a catalyst (e.g., a platinum catalyst). This mixture can be cured via an addition-cure chemistry at elevated temperatures (e.g., 20 seconds at 160°C). Implant-grade room-temperature-vulcanizing (RTV) silicone adhesives are also available; these adhesives can be cured at room temperature through exposure to ambient moisture in the air.

The silicones that have been used in breast implants are gels. These silicones are highly cross-linked polysiloxane networks swollen with polydimethylsiloxane (PDMS). The PDMS fluid is not chemically bound to the cross-link network, but is instead retained only by physical means (like water in a sponge).

Pressure-Sensitive Adhesives. Pressure-sensitive adhesives are used in medical tapes and labels. The adhesive is permanently in tacky form at room temperature and can be used to join various materials with the application of moderate pressure. Pressure-sensitive adhesives are not normally used in sustained-load-bearing applications and can often be removed without leaving a residue.

Most pressure-sensitive adhesives are based on elastomers (e.g., natural or synthetic rubbers), acrylics or hot-melt thermoplastics, tackifiers, or antioxidants. Single- or double-coated pressure-sensitive adhesives are employed in many medical applications. These tapes are available as woven, nonwoven, or elastic materials; they are compatible with skin and can be easily removed with minimal residue. There are medical tapes and transfer adhesives available that can withstand both gamma and EtO sterilization.

Pressure-sensitive adhesives have also been used in transdermal drug-delivery systems.5 This type of system offers many advantages over conventional oral medications, mainly because it delivers less drug to achieve the same therapeutic effects. The transdermal method delivers drugs directly into the bloodstream via skin and then the liver, rather than by absorption in the gastrointestinal system. A transdermal drug-delivery system usually consists of a patch with drug formulations, an adhesive to maintain contact with the skin, a release liner to protect the patch during storage, and a backing layer that protects the patch from external factors during use.

Other medical applications of pressure-sensitive adhesives include wound coverings and closures, surgical drapes, electrosurgical grounding pads, ostomy mounts, and electrocardiograph electrode mounts.9

Adhesives in Medical Electronics. In the area of electronic components for medical devices there are a wide range of polymeric materials available. They are used variously as attachments, substrates, and interconnections, and for encapsulation or protection.

In recent years, the use of adhesives and encapsulants in medical electronics and implantable devices has increased considerably. This is due to the availability of a wide range of materials that offer different properties, better adhesion, improved durability, suitability for automated dispensing, and rapid curing.

Typical examples are the use of epoxies in ultrasound catheters and pacemakers and light curing adhesives in medical electronic packages. A general classification of adhesives used in electronic applications is shown in Figure 4.

SURFACE PRETREATMENT

Successful material-joining adhesives normally require suitable surface treatment of the adherents prior to bonding.7 The selection and application of an appropriate surface treatment is one of the major factors for achieving good wettability and improved long-term durability in adhesively bonded joints. Inadequate or unsuitable surface treatment is one of the most common causes of premature degradation and failure. The function of surface treatment includes the removal of contaminants or weak boundary layers and the alteration of surface chemistry, topography, and morphology to enhance adhesion and durability.

Surface preparation techniques are generally divided into mechanical or chemical methods. Mechanical methods include abrasion, grit blasting, and shot blasting. A laser technique has also been tried.10–11 Chemical methods include degreasing, etching, and anodizing; the use of adhesion promoters; and flame, corona, and plasma treatments.

In many applications, simple degreasing and abrasion is sufficient to provide good adhesion. Medical polymers with low surface energy and bondability, however, require a more specialized treatment (e.g., plasma treatments) in order to provide better adhesion and joint durability. Some adhesion promoters can also enhance the bondability of certain polymers. Recently, new grades of adhesives with the ability to bond polyolefins without pretreatment (e.g., polyethylene) have become commercially available.

DISPENSING TECHNIQUES

Mixing. The mixing and preparation of adhesives should be in accordance with manufacturers' instructions. Appropriate health and safety precautions must also be taken. Only adhesives from the same batch number should be used in a single joint to prevent uneven properties. Adhesives should be applied immediately after surface preparation is complete, and applied in such a manner that minimizes the risk of air entrapment in the joint.

Manual mixing and application should be avoided, if possible; it can introduce voids, bubbles, and regions of incomplete mixing. Using handheld dispensing guns to dispense single- or multipart paste adhesives from prepackaged cartridges is recommended. For high-volume production, semiautomated or automated pump dispensers should be employed.

Component parts of the adhesive are mixed during the dispensing process by forcing them through a static mixing nozzle. When a new nozzle is fitted, or at the beginning of a new production run, a 50–75-mm bead of adhesive should be dispensed onto scrap material to ensure that good mixing is achieved and that any aged adhesive is removed.

Basic Dispensing Principles. Dispensing involves the combination of several functions, depending on the method used. These include the following:

  • A supply of energy to the bulk adhesive to move it through feed pipes to a valve or pump, then to a dispensing nozzle.
  • Control of the valve or pump, to vary the volume applied during each cycle.
  • Control of the speed of movement between nozzle and component—either the component or the dispensing nozzle can be moved, depending on the application.

There are many methods of dispensing adhesives. Because of cost restraints and processing considerations (i.e., the speed and volume of the adhesive to be dispensed), the techniques considered most suitable are cartridges, pressure/time systems, pumps, and microjet printing.

Cartridge Dispensing. Cartridge dispensers may be single or double cylinders, with mechanical or air movement of the pistons. Figure 5 illustrates how applying pressure to the plungers allows equal measures of part A (adhesive) and part B (hardener) to be mixed automatically in the mixing nozzle. The mixed adhesive is then applied to the component as a single shot. Sizes typically range from 5 ml to 1 L. Cartridge dispensing is generally a manual process suited to batch production runs.

Pressure/Time Systems. In a pressure-based system a tank is pressurized by air, which drives adhesive through a feed pipe to a valve. A time relay initiates the valve opening and closing, controlling the volume of adhesive dispensed.

Adhesives with viscosities up to approximately 10,000 poise can be dispensed. Bulk containers vary from 50 ml to 100 L. Pressure/time dispense systems are suitable for high-volume production rates, in semiautomated or automated processes. Pinch valves or diaphragm valves can be employed to control dispense volumes and to prevent adhesive stringing between components.

Pumps. The dispensing of adhesives by pumping techniques can be achieved in a number of ways, depending on whether a one- or two-part adhesive is dispensed.

One-part adhesives are dispensed using direct metering extrusion pumps, shown schematically in Figure 6. An electric motor pushes a follower plate into a drum of adhesive, which is then extruded through a hose to the dispensing valve. This technique is used for medium- and high-volume production rates.

Two-part adhesives are generally dispensed by volumetric pumps for semiautomated and automated medium-high-volume assemblies. A typical pump is illustrated in Figure 7, which is similar in principle to the cartridge system described above. Metered dispense systems are capable of processing adhesives with mix ratios of 1:1 or up to 15:1.

Microjet Printing. One of the most attractive precision dispensing methods for polymeric resins and particle-filled fluids is the use of microjet printing technology.12 This technology is based on piezoelectric demand-mode ink-jet printing, which can produce droplets of polymeric resins 25–125 µm in diameter, at rates up to 1000 drops per second.

Two main types of approaches are typically used in ink-jet printing: drop-on-demand (DOD) and continuous, charge, and deflect.12

The DOD method can produce smaller droplets (10–100 µm) at lower frequency (up to 10 Hz).13 The continuous, charge, and deflect method provides larger droplets (up to 0.5 mm in diameter) at rates up to 1 MHz; it is particularly suitable for high-speed, large-area coverage.14

There are two main material requirements for dispensing by the DOD method. First, the polymeric resin has to be stable and reducible in viscosity to the 0.4 poise level; this is typically achieved by heating or diluting with a suitable solvent. Second, the printed polymer must maintain the required properties for the intended application after solidification on the substrate.

Typical 100% solid polymeric materials may be jet printed provided they do not degrade at the elevated temperature at which the required viscosity is reached. For diluted versions of printable polymeric resin, it is essential to select a solvent that does not evaporate too rapidly and thus block the ink-jet head. Polymeric resins containing fillers (e.g., filled adhesives) can also be printed providing they satisfy the viscosity and chemical stability criteria and the filler particle size of <10 µm.

Suitable grades of a range of commercially available adhesives can be successfully printed in picoliter volumes with consistency and good printing quality. The microjet printing technique is emerging as one of the most attractive dispensing techniques for many new micro, optoelectronic, and medical device manufacturing applications.

Requirements of Dispensing Equipment. The choice of a dispensing system depends on several different factors, such as:

  • The adhesive type. (A single component requires no mixing; a two-part adhesive requires mixing in the nozzle or on the substrate.)
  • Viscosity, which determines whether pumping or cartridges will be used.
  • The curing mechanism. This mechanism must prevent adhesive hardening within the dispenser.
  • The curing time. This must be calculated to prevent hardening in the dispenser.
  • Cycle time, which should fit the production schedule.
  • The factory environment.
  • The volume of adhesive used per cycle and per day.
  • The accuracy required per component.
  • The overall cost.

CURING TECHNIQUES

The curing of polymeric adhesives or encapsulants can be achieved using moisture or catalysts in the presence or absence of air (e.g., in the absence of air for anaerobics) at room temperature; thermally, at elevated temperatures; or photochemically, using irradiation (e.g., UV or visible light). Heat-activated curing can be initiated using the following methods:

  • Local heat application at the joints.
  • Overall heat application.
  • Conventional or conduction ovens.
  • Hot-plate heating.
  • Infrared heating.
  • Vapor-phase heating.
  • Liquid-phase heating.
  • Laser heating (Nd:YAG or CO2 lasers).
  • Microwave—particularly variable-frequency microwave (VFM).

There are a range of materials available that can be cured using radiation sources such as UV and visible light. Acrylated resins (acrylated epoxies, polyesters, polyurethanes, and silicones) can be cured using radiation energy. Radiation-curable adhesives or encapsulants generally consist of low- or medium-molecular-weight resins (called oligomers), monofunctional or multifunctional monomers, additives, pigments, photoinitiators, or photosensitizers.

A typical UV energy of 80–120 mW/cm2 produced from a UV source (300–400-nm wavelength ) is usually sufficient to cure a UV-curable adhesive within 10 to 60 seconds. An alternative radiation curing technique is to use visible light (470-nm wavelength; see photo on page 58). Radiation curing adhesives are often used for joining clear polymers in disposable and nondisposable medical devices. In general, both UV and visible-light curing can be achieved using light boxes or focused beams and light guides. In some cases heat is also employed to encourage the curing process, for the completion of curing, or to cure areas that cannot be reached by radiation energy.

Compliance with USP and ISO Requirements. Tests to determine the biological reactivity of polymeric materials and medical devices are described in the USP and in the ISO 10993 standard.15

According to the injection and implantation testing requirements specified under the USP biological reactivity tests, in vivo polymers are classified on a scale of I to VI.16 To test a polymer, extracts of the material are generated in various media. The extracts are then injected systemically and intracutaneously into rabbits or mice to evaluate their biocompatibility. Class I, II, III, and V polymers do not require implantation testing; Class IV and VI polymers do require such testing.

ISO Standard 10993 consists of 16 parts. Each part describes specific tests that include a variety of toxicity tests. For example, the tests in Part 10 are used for the identification and quantification of degradation products from polymers.

Many polymeric adhesives may be qualified as USP Class IV and Class VI materials. These materials can pass the relevant incutaneous-toxicity (in vivo), acute-systemic toxicity (in vivo), and implantation (in vivo) testing requirements. Merely passing USP Class VI standards does not guarantee that an adhesive will meet FDA requirements in a particular application; however, passing the test is a strong indication of the nontoxicity of an adhesive.

Certain types of medical-grade epoxy adhesives are capable of being sterilized by autoclaving, EtO, and chemical methods. These epoxy resins can be used in medical devices that require sterilization prior to use.

CONCLUSION

The use of adhesives for joining medical device components has increased significantly in recent years. The selection of suitable adhesives and appropriate bonding procedures—including surface preparation, adhesive dispensing, and curing—are critical parameters in the successful use of joining technology.

Although there are many commercially available medical-grade adhesives, thorough investigation is required before they should be used in new applications. It is also important to remember that in addition to determining the initial joint strength, users must investigate the durability of the bonded components in intended service environments (e.g., exposure to low and high temperatures, stress, fluids, or sterilizations). Designing accelerated aging tests that simulate service environments is critical in providing realistic durability data. It is also essential in the performance assessment of medical devices to interpret the aging data and predict the life span of the joint.

The emergence of new types of adhesives and the further development of precision dispensing and rapid curing technologies offer many attractive opportunities for joining medical devices.

ACKNOWLEDGMENTS

The author wishes to thank material suppliers and users, particularly Loctite UK, Epoxy Technology, Braun Medical, Emerson and Cuming, and Dymax for their support and for supplying some of the photographs for this publication.


REFERENCES

1. SB Dunkerton, "Joining of Materials for Medical Applications" (paper presented at Third Annual Medical Design and Materials Conference, Amsterdam, The Netherlands, April 24–25, 1995).

2. SM Tavakoli, EL Nix, and AR Pacey, "Joining Components of a Cardiac Catheter Tip Assembly with Electronically Conductive Adhesives," ANTEC 3 (1995): 3362–3366.

3. SM Tavakoli, "Adhesive Bonding in the Medical Industry, Designing Successful Assemblies—Critical Issues in Joining and Bonding" (paper presented at MEDTEC, Amsterdam, The Netherlands, October 21–23, 1997).

4. G Ciapetti et al. "Toxicity of Cyanoacrylates In Vitro Using Extract Dilution Assay on Cell Cultures," Journal of Biomaterials 15, no. 2 (1994): 92–96.

5. M Rimpler, "Gluing a Challenge in Surgery," International Journal of Adhesion and Adhesives 16 (1996): 17–20.

6. HN Himel, "Tissue Adhesives in Plastic and Reconstructive Surgery," in Surgical Adhesives and Sealants—Current Technology and Applications, chap. 19 (Lancaster, PA: Technomic Publishing, 1996).

7. RH Estes, "The Suitability of Epoxy-Based Adhesives for Use in Medical Devices," technical paper GB-63, Epoxy Technology (Pembroke, MS).

8. SM Tavakoli et al. "A Novel Polymeric Coating for Enhanced Ultrasound Imaging of Medical Devices" (paper presented at ANTEC 2001, May 6–10, 2001).

9. I Webster, "Recent Developments in Pressure-Sensitive Adhesives for Medical Applications," International Journal of Adhesion and Adhesives 17, no. 1 (1997): 69–73.

10. SM Tavakoli and ST Riches, "Laser Surface Modification of Polymers to Enhance Adhesion: Part 1 Polyolefins," ANTEC May 1 (1996): 1219–1224.

11. SM Tavakoli and ST Riches, "Laser Surface Modification of Polymers to Enhance Adhesion: Part 2" (paper presented at ANTEC 2000).

12. DJ Hayes, ME Grove, and WR Cox, "Development and Application by Ink-Jet Printing of Advanced Packaging Materials," in Proceedings of the International Symposium on Advanced Materials Process, Properties and Interfaces (1999), 88–92.

13. WT Pimbley, "Drop Formulation from a Liquid Jet: A Linear One-Dimensional Analysis Considered as a Boundary Value Problem," IBM Journal of Research and Development 29 (1984): 148.

14. DB Bogy and FE Talke, "Experimental and Theoretical Study of Wave Propagation Phenomena in Drop-on-Demand Ink Jet Devices," Journal of Research and Development 35, no. 1 (1989).

15. SM Tavakoli, "Adhesives and Coatings—The Cheaper, Greener, Higher Productivity Approaches to Rapid Curing, Part II," TWI Bulletin 42, no. 1 (2001) .

16. SM Tavakoli, "Adhesives and Coatings— The Cheaper, Greener, Higher Productivity Approaches to Rapid Curing, Part II," TWI Bulletin 41, no. 6 (2000).

ADHESIVES IN MEDICAL DEVICES

Figure 1. Bonding components of an ultrasound catheter tip with conductive adhesive.

Catheters. Figure 1 shows a silver-loaded, electrically conductive adhesive that is used to join a piezoelectric transducer (PZT) ring to a tungsten carbide (WC) tube. The ring and tube are two components of a cardiac catheter tip, which functions as part of an ultrasound imaging device for the quantitative and diagnostic analysis of coronary arteries.

After a series of investigations on the catheter tip, an optimized condition was found. The manufacturer inserted a conducting adhesive between the WC and the PZT components and a curing process was used that resulted in a void-free, 80-µm conducting layer with the desired acoustic properties. These ultrasound catheter tips have been taken through mechanical product testing to clinical evaluation trials.

Figure 2. An adhesively bonded balloon catheter.

In addition, cyanoacrylates and curing adhesives are used for joining latex balloons onto PVC, urethane, and multilumen tubes for balloon catheters. Figure 2 shows an example of adhesive bonding in balloon catheters for angioplasty.

Pacemakers. A two-part, silver-filled epoxy is used for bonding critical components in hybrid circuits within pacemakers.

Needles. Lancets, syringes, injectors, hypodermics, blood collection sets, and introducer catheters are assembled using acrylic-based adhesives. The polypropylene moldings of a drug-administration gun are often bonded together using a cyanoacrylate adhesive.

Figure 3. Epoxy-bonded end caps on a blood filter.

Polycarbonate Devices. Acrylic-based adhesives are used in bonding polycarbonate medical devices including filters, blood-pressure transducers, arteriograph manifolds, cardiotomy reservoirs, and blood oxygenators. Epoxies are also used to join filter components. Figure 3 illustrates the use of a two-part epoxy for bonding end caps to the main tube of a blood filter.

Masks. UV-curable acrylic adhesives are employed for bonding cushion (flexible PVC) to nose (rigid PVC) in anaesthesia and face masks.

Figure 4. A drug-delivery tube bonded with acrylic adhesive.

Tube Sets. Blood and drug delivery sets and suction and IV tubes are assembled using acrylic-based adhesives. An example of the acrylic and PVC components of a drug administration tube, bonded with an acrylic adhesive, is shown in Figure 4.

Copyright ©2001 Medical Device & Diagnostic Industry

Radiolucent Structural Materials for Medical Applications

Originally Published MDDI June 2001

Medcial Plastics and Biomaterials

Radiolucent Structural Materials for Medical Applications

For devices that are transparent to x-rays, thermoplastic and carbon-fiber composites provide properties that are competitive with traditional metals.

Barry Chadwick and Chris Toto

New materials are often the necessary building blocks for product development and technology breakthroughs in the medical device industry. With novel procedures and treatments emerging rapidly, the equipment and devices required to enhance such advances are frequently limited only by their materials of construction.

In the realm of x-ray technology, there has been a recent upsurge in use brought about by enhanced equipment that requires lower levels of radiation. These innovations have in turn spurred the need for a new breed of materials to further improve device performance and to refine treatment. This article describes the emergence of one such group of materials, the family of radiolucent structural composites.

Figure 1. Unlike traditional metals, radiolucent structural materials are transparent to x-rays.

TRADITIONAL MATERIALS OF CONSTRUCTION

Traditionally, metals such as aluminum, stainless steel, and titanium have been used for structural components in the medical device industry. But these materials are radiopaque—that is, they obstruct x-rays. Accordingly, a metal device located in front of a trauma region would restrict x-ray visibility to the region.

Plastics are inherently radiolucent; with mechanical properties generally inferior to those of metals, however, plastics normally cannot directly replace structural metal components. For example, flexural modulus—a measure of material stiffness—is typically several hundred thousand pounds per square inch (psi) for many unreinforced thermoplastics; in contrast, the flexural modulus of aluminum is 10 million psi. Many applications require the rigidity of metals and thus cannot use these unreinforced thermoplastics. For instance, external fixators used to support bone fractures during the healing process must be rigid enough to maintain bone alignment despite the rigorous pressures and forces placed on them by patients—forces that would deform traditional plastics beyond acceptable limits and potentially result in poor healing of the trauma area.

A NEW BREED OF MATERIALS

A growing number of device applications—including halos, nail guides, x-ray equipment accessories, and others—demand both the physical properties of metals and the radiolucency of plastics. To meet new engineering challenges, medical manufacturers are turning toward radiolucent structural materials, which are transparent to x-rays and provide the necessary mechanical performance for the structural components used in surgical equipment and devices (Figure 1). These materials—generally composites—can provide mechanical properties competitive with those of some metals, featuring flexural moduli as high as 8 to 17 million. They are also much lighter than traditional metals, with attainable densities as little as one-half that of aluminum and one-sixth that of stainless steel. For a product such as a fixator, which patients wear following surgery, reduced weight is a major benefit.

A COMPOSITE SOLUTION

The most recent varieties of radiolucent structural materials combine the toughness of a thermoplastic matrix with the strength of carbon-fiber reinforcements. Carbon has strength and stiffness properties that, in many cases, exceed those of metals. Carbon is also inherently radiolucent. Unfortunately, carbon itself is brittle and difficult to form into complex shapes. As a fiber, however, carbon can provide substantial reinforcing properties to plastics.

Fiber reinforcement of plastics is a long-established practice. The two most common reinforcements are glass fiber and carbon fiber. Glass-fiber reinforcements are typically used in general-purpose applications because of the good balance they provide between mechanical performance and cost. Although carbon is often more expensive, it is generally more rigid and has a lower density than glass. This has resulted in carbon-fiber-reinforced plastics being the material of choice in many high-performance structural applications, such as those found in the aerospace industry. For medical uses, there is another substantial difference between carbon and glass fibers: carbon is far more radiolucent, and thus becomes the reinforcement of choice for applications that require x-ray transparency.

Regarding the plastic matrix, reinforcements can be added to either thermosets or thermoplastics. One key distinction between these two types of materials is the reprocessibility of thermoplastics. Simply stated, thermosets, such as phenolics and epoxies, cannot be remelted once formed into the desired part; but thermoplastics—including a wide range of materials such as nylons, polycarbonates, and polyketones—can be remelted and re-formed.

There are other distinctions between these material families that are more pertinent to the medical industry, however. For example, thermoplastics tend to exhibit better toughness properties than thermosets. For applications requiring high impact resistance, such as nail guides or x-ray cassettes, this can be a very important distinction. In other specific cases, thermoplastics can be selected for their superior resistance to moisture degradation, which makes them suitable for applications requiring sterilization. Additionally, thermoplastics generally have an unlimited shelf life, thus avoiding the storage and refrigeration problems associated with thermosetting polymers.

ANATOMY OF A RADIOLUCENT COMPOSITE

The broadest definition of a radiolucent composite includes the entire family of plastics that contain a fiber reinforcement to increase structural properties yet still maintain transparency to x-rays. For reasons previously discussed, the trend in medical radiolucent composites increasingly focuses on thermoplastic resins with carbon-fiber reinforcement.

Several material variables affect the performance of these thermoplastic composites. Three of the most important are the thermoplastic resin matrix, the carbon-fiber, and the manufacturing method type and orientation used.

OVERVIEW OF THERMOPLASTIC RESINS

A wide variety of thermoplastic resins are used in the medical industry. The selection process for a resin invariably begins with application requirements. Most applications have multiple requirements that must be met, which narrows the list of candidate materials considerably. Some of the most common selection criteria include chemical resistance, temperature resistance, impact resistance, elongation or flexibility, strength, stiffness, clarity, dimensional stability, and biocompatibility, among others.

Resin selection is a complicated and challenging process of matching material capabilities with design requirements. There are at least two important aspects of material selection that should always be considered during this process. First, material property enhancements often involve trade-offs. For example, the selection of a stiffer resin material frequently means the material will have less elongation.

Second, performance often has a price. The higher the performance capabilities of the material—especially if it has multiple property attributes—the higher the price. The price of the thermoplastic matrix, however, is only one component in the overall price of a composite. The cost of carbon fiber and of processing can substantially affect the price of the finished material. Relative to radiolucent composites, it is often helpful to consider polymers in four broad categories for the purpose of pricing and performance:

Commodity polymers, which include materials such as polypropylene and polyethylene, are not typically used for carbon-fiber-reinforced composites.

General-purpose polymers tend to be moderately priced while offering a good combination of properties, especially when reinforced. For instance, polyamides, commonly referred to as nylons, come in a wide variety of formulations, all of which generally exhibit a good combination of strength, toughness, chemical resistance, and low friction.

Performance polymers include materials that are higher in price yet offer unique attributes in selective performance properties. Polyetherimides, for example, exhibit a good combination of high-performance properties, including temperature and chemical resistance, dimensional stability, toughness, strength, and chemical resistance. Polyphenylene sulfides demonstrate excellent chemical and temperature resistance, electrical properties, and high strength, but they typically do not withstand impact very well.

High-performance polymers, although the highest priced of the thermoplastics, can frequently offer properties unavailable even with metals or other types of materials. An example of a high-performance polymer would be polyaryletherketone, which exhibits very high temperature and chemical resistance and has excellent toughness and strength.

OVERVIEW OF CARBON-FIBER REINFORCEMENTS

In most composite applications, mechanical strength and stiffness requirements are key factors in material selection decisions. The structural properties of thermoplastics can be significantly enhanced by the fibers added to the matrix, and there are several factors associated with the fiber that affect these properties. Fiber type, length, quantity, and orientation are a few of the important variables related to fiber selection.

Fiber Type. There are a wide variety of carbon fibers, as a result of differing manufacturing methods and end-use application requirements. Generally similar fibers can in fact demonstrate substantially different properties in areas ranging from mechanical to electrical performance. Additionally, some fibers are specially treated to enhance bonding to the polymer matrix. This bonding is sometimes necessary to maximize the mechanical characteristics of the overall composite.

Fiber Length and Orientation. The relationship between fiber length and diameter (L/D) is referred to as the aspect ratio. Fibers with higher aspect ratios typically offer improved mechanical properties when added to thermoplastics. Higher aspect ratios can be achieved by increasing the length or reducing the diameter of the fiber. For structural components, fiber length is frequently the focus for enhancing mechanical properties, and can vary from chopped to continuous.

A polymer containing chopped fibers will be considerably stronger compared with the same resin in an unreinforced state. The percentage of chopped fibers added is generally from 10 to 40% by volume. Amounts exceeding 40% may be difficult to process because of the absence of sufficient resin for flow properties. Percentages less than 10% typically do not provide adequate reinforcement. Chopped fibers are most often randomly oriented. One of the key benefits of this random orientation is the relative uniformity of properties in all directions.

Continuous-fiber reinforcement offers the highest possible strength and stiffness. The percentage of continuous fibers used is typically in the 50-65% range by volume. On the upper end, this is primarily limited by the proportional relationship of the fiber and resin, since there must again be sufficient resin to maintain a strong matrix. Continuous fibers can be oriented in different ways to achieve desired structural properties. The most common continuous-fiber orientations are unidirectional and bidirectional.

Unidirectional Continuous Fibers. The structural properties of composites with unidirectional fiber orientation vary drastically when measured parallel (0°) as opposed to perpendicular (90°) to the fibers (Table I). In the parallel direction, the overall material properties most closely resemble those of the fiber, whereas in the perpendicular direction, the properties most closely resemble those of the resin. Thermal expansion also varies depending on fiber direction. One of the more common uses for unidirectional fiber composites is in filament-wound or fiber-placed tubes.

Property
Parallel to Fiber
Perpendicular to Fiber
Tensile strength (ksi) 300 12.5
Tensile modulus (msi) 20 1.5
Flexural strength (ksi) 290 20
Flexural modulus (msi) 18.1 1.3
Coefficient of thermal expansion (in./in./°F) .15 x 10-6 17 x 10-6
Table I. Properties of unidirectional carbon-fiber/PEEK composite.

Bidirectional Continuous Fibers.This type of fiber orientation offers a good balance of properties in two directions (50% in the parallel and 50% in perpendicular direction). Stacking unidirectional plies on top of one another with each layer turned 90° from the previous layer can form a bidirectional fiber structure. Alternatively, the fibers or groups of fibers can be woven into symmetrical patterns to form layers. These layers can then be stacked on one another (Figure 2).

MANUFACTURING OPTIONS

Carbon-fiber-reinforced thermoplastic components can be produced using several manufacturing methods. The selection of a manufacturing method depends on the material, production volume, budget for tooling and part costs, and other factors. The most common methods used for radiolucent structural components are compression molding, injection molding, and extrusion. Both compression molding and extrusion frequently require postmachining to produce final parts, whereas injection molding can frequently produce parts in finished form.

Compression Molding. In this process, a predetermined amount of pressure is applied at a specific temperature above the melt point of the resin. Compression molding can be used to make both chopped- and continuous-fiber composites.

Figure 2. Fibers woven into layered patterns.

One of the primary benefits of the process is that it is fairly quick and can be used for plates or custom shapes that are later machined to finished form. Compression molding is often recommended for small to moderate production runs.

Fiber Placement. This process places fiber-reinforced, unidirectional tape—also known as prepreg—upon a mandrel. As the tape is laid down, it is heated and subjected to a consolidating force. Individual layers are built up until the desired thickness is achieved. Normally, this method is used to make tubes, although more-complex geometries are also possible. Fiber placement is a highly automated process that can be tightly controlled for high repeatability and precision.

Fiber Type
Processing Method Available
Compression
Fiber Placement
Injection
Extrusion
Continuous Yes Yes No No
Chopped Yes No Yes Yes
Table II. Processing options for composite materials.

Injection Molding. This injection molding process melts resin and forces material to flow into a mold to form finished parts. Because of the equipment used for the process, only chopped fibers can be employed for injection molding. This method offers higher physical properties when compared to chopped-fiber, compression-molded parts and is a good approach for large quantities or precision-tolerance parts.

Part Volume
Part Cost Versus Processing Method
Compression
Fiber Placement
Injection
Extrusion
High Poor Good Excellent Good
Low Excellent Good Poor Good
Table III. Comparison of composite part economics versus processing method.

Extrusion. Processing via extrusion produces shapes of standard cross sections. As with injection molding, the equipment can manage only chopped-fiber reinforcements. But unlike injection molding, which typically involves high injection pressures, extrusion uses lower pressures, which enhances the mechanical performance of the parts. Accordingly, the physical properties of chopped-fiber-reinforced parts made by extrusion are typically lower than those of similar parts made with injection molding. Generally, the structural performance of these components lies between that of injection-molded and compression-molded parts made from the same material. The extrusion process can be used to make large, rectangular plates and some standard cross-section shapes. In addition, extrusion is an economical approach for prototype development.

MATERIAL SELECTION PARAMETERS

Selecting the right radiolucent composite requires an understanding of the inherent advantages and limitations of the different fiber types and processing methods. Again, some fiber types are compatible only with certain processing methods (Table II). In turn, these processing methods can have an impact on part economics (Table III). The processing method and fiber type can also have a substantial effect on the characteristics of the finished part (Table IV).

Fiber Type Process
Key Attributes
Structural
Design Freedom
Radiolucency
Continuous Compression Excellent Good Excellent
Continuous Fiber Placement Excellent Good Excellent
Chopped Compression Fair Good Excellent
Chopped Injection Very Good Excellent Excellent
Chopped Extrusion Good Very Good Excellent
Table IV. General carbon-fiber-reinforced composite performance comparison.

The most advanced radiolucent composites combine high-performance polymers and bidirectional carbon fibers to form uniformly sound structural parts able to withstand aggressive use as well as multiple sterilization cycles. Many of these components can be designed for reuse in surgical tools. Table V compares the properties of one such material with those of aluminum.

Property
Bidirectional Carbon Fiber/PEEK (0°/90° direction)
Aluminum (2024-T3)
Density (lb/in.)
0.056
0.100
Flexural strength (ksi)
1.37
67
Flexural modulus (msi)
7.7
10.5
Specific strength (strength/density)
2446
670
Specific modulus (modulus/density)
137.5
105
Thermal expansion,70-300°F (in./in./°F)
1.6 x 10-6
14 x 10-6
Melting point (°F)
640
936
Table V. Comparative structural properties of PEEK composite and aluminum.

CONCLUSION

Innovative materials are increasingly among the critical elements required for product development and technology breakthroughs in the medical industry. A clear example of this can be found in the advanced procedures incorporating the latest x-ray technology that have created the need for radiolucent structural materials. These composites of thermoplastic polymers and carbon fibers are transparent to x-rays and provide structural properties that, in many cases, are competitive with those of metals. With a thorough understanding of the candidate polymers, fiber types, and processing methods, designers can select a radiolucent composite to satisfy many of their daunting materials-related challenges.

Photos courtesy of GREENE, TWEED, AND CO. (KULPSVILLE, PA)

Copyright ©2001 Medical Device and Diagnostic Industry

Putting PMAs, 510(k)s on a Paper Diet

Originally Published MDDI June 2001

Washington Wrap-up

Putting PMAs, 510(k)s on a Paper Diet

Faced with an ever-increasing workload, CDRH is seeking methods to reduce the bulk of product submissions.

James G. Dickinson

Now into the ninth month of his tenure as CDRH's director of device evaluation, Bernard Statland has ordered a review of his staff's product submission volume. He wants to determine if his reviewers are wading through too much unnecessary information, and thereby slowing decision times.

The former industry CEO and clinical pathologist says that he sometimes sees submissions consisting of as many as 10 volumes of material. His reviewers "feel obligated to read everything that is sent," he says. "If sponsors could send us everything that's relevant in a smaller [package], and better organized, then perhaps we can be more timely. We're just beginning to look at it."

Statland believes that the spirit of FDAMA's "least burdensome" provision, as he understands it, is for FDA to have only the information that is relevant.

Statland does acknowledge that PMA decision times slowed marginally last year, but maintains that the three-year average is at steady-state. As a former industry member, however, Statland says he knows "the burn rate of a dollar when products don't come to market," and he believes there are things he can do to improve review performance.

"If it's a resource problem, I can lobby for more resources. If we're spending too much time on things that are unnecessary, we can develop procedures to decrease that," he says. "Efficiency," Statland emphasizes, "is right up there on the top of my list of priorities."

But Statland also stresses that the goal of increased efficiency is the mutual responsibility of both industry and the agency. "It's not just FDA's review time," he says. "It's really the combination of FDA and the sponsor. If the companies have their submissions presented in a complete manner, easy to read, easy for us to absorb, it will make our job a lot easier."

Statland has spent considerable time speaking on the topic with several groups, including AdvaMed. "I talk about PMA match, which means that the companies and FDA have to match efforts with each other," he says. "[FDA] should let the companies know what it expects, and the companies should hopefully come up with that. It will be a mutual benefit."

"Clinical pathologists"—Statland's former occupation—"are judged on two things: accuracy and turnaround time. So I'm used to that," he adds. "That's the same thing as effectiveness and efficiency."

Statland also believes that the pre-IDE phase is very important. "We need to have the sponsor and ODE agree on what the requirements should be. Then the companies should have a complete submission, so we don't have to send a deficiency letter."

Speaking about the new direction he struck recently in breaking the 20-month deadlock involving the approval of TMJ Implants' Fossa Eminence device (his decision requires labeling to advise patients that there could be nondevice alternatives for their treatment), Statland says product labeling is based on risk sharing.

"We're sharing risk all the time," he says. Statland believes the physician should determine the risk, and tell the patient, "Here's what you'll gain, here's what you possibly could lose," he says. "I don't think anything can be 100% effective, or 100% safe.... Once we let a product go through the approval threshold, then that is risk sharing."

But Statland adds that in order to share risk, the physician must be knowledgeable. "I think it is so important for the physician to read the insert, and it's so very important for the patient to be able to know what could happen."

Just as presenting the optimal PMA submission is the mutual responsibility of the agency and sponsor, Statland says, so too is the broader issue of the device's place in therapy. In a slide presentation he makes to professional and industry meetings, Statland speaks of the shared responsibility of the device maker, the physician, the patient, and FDA.

"The company has the responsibility of making something safe, making it effective, and [providing] full disclosure," he says. "The physician has the responsibility of absorbing what the company comes up with. Then the patient has more and more responsibility for his or her own health."

And Statland adds that the agency has the largest role: "FDA must guarantee that all these things happen; [it] must ultimately evaluate that what has been presented is correct, that [the device] meets the threshold of safety and effectiveness, that the insert is an honest label." When the product hits the marketplace, Statland says, FDA must "monitor [it] to see what happens down the road."

Statland is committed to full disclosure by device manufacturers, he says. Ideally, then, full disclosure becomes the first link in a device information chain linking physicians and patients. Patients, who are becoming more empowered, increasingly come to their physicians armed with pages of information about their problem that they have taken from the Internet. FDA, Statland says, is increasingly playing the role of a catalyst in helping to disseminate objective device information to patients. He cited the agency's Lasik Web page, and suggested that this may be a model for other devices in the future.

Bush Budget Seeks More for FDA

President George W. Bush's first budget request to Congress sought a general 10% increase for FDA (8.5% for the medical device program). It also attempted to reverse a Clinton-era habit of making the agency pay for its staff's cost-of-living salary increases out of the money appropriated for FDA's industry programs. According to agency officials, this means that for the first time in eight years they will be able to avoid program reductions—though they will still be far short of expanding any programs, particularly in the medical device arena.

As part of the Bush budget request, FDA vows to complete first action on 90% of new device applications (PMAs) within 180 days, compared to 74% in 1999.

In support of the administration's budget request for FDA, AdvaMed called on Congress to ensure that FDA has adequate resources to meet its product review timelines.

According to the group, breakthrough devices and combination products (those products considered to be both a device and a drug) have experienced "significant premarket review delays." The group also warned that without adequate funding and resources, "premarket review challenges posed by innovative medical technologies will only increase in the coming years, as FDA faces an ever-increasing number of breakthrough products."

AdvaMed pointed to a recent report that found that medical device and diagnostic manufacturers have doubled their R&D over the past decade. It recommended that "FDA should be given the resources and expertise needed to streamline the entire medical technology development and review process... to begin the process of preparing FDA for a new age of rapid biomedical and pharmaceutical innovation. This new age is rapidly approaching, and the time to start preparing is now."

AdvaMed urged Congress to improve its dialog with FDA to fully understand the total resources needed by the agency to meet its statutory review timeframes. "Such a dialog must also include the resources needed at the Drug and Biologics Centers to review combination device, drug, or biologic products." The group offered its assistance in facilitating and participating in such a dialog.

Inadequate Trending Cited in Warning Letter

An FDA inspection of Kimberly-Clark subsidiary Ballard Medical Products (Draper, UT) revealed significant GMP and quality system regulation deviations, according to a recent agency warning letter. The firm manufactures microCount and microCount Lite liquid scintillation counters, trach care kits, pain management kits, diagnostic test kits, and oral health products.

FDA said its inspection found that the firm's management reviews of its own quality system were not effective. For example, the firm did not have adequate trending procedures and its management review procedure lacked frequency details.

According to the agency, the firm also had inadequate corrective and preventive action procedures and failed to trend customer complaints. In addition, Ballard was found to have been failing to investigate the cause of nonconformities relating to products, processes, and quality systems. FDA said that several complaints involved patient trauma; no medical device reporting submissions were completed, however.

According to the warning letter, the com- pany notified FDA that it has contracted with outside consultants to assist in the correction of the identified problems. FDA told the company that many of its responses to the inspection's FDA-483 were inadequate. It added that certification from the company's outside consultants will be required to ensure that an audit of the firm's facility has confirmed that all corrections have been completed.

FDA Enforcement Actions Profiled

FDA has detailed its major enforcement actions against medical device manufacturers in FY 2000 in its just-released Enforcement Story report.

One case involved an FDA inspection of Delta Medical Center (Memphis, TN). The inspection revealed that the facility failed to submit a medical device report (MDR) after learning that certain devices had malfunctioned and may have caused or contributed to a serious injury. A September 2000 warning letter cited one malfunction of a cardiac pacemaker, one patient injury in July 2000 as a result of a broken belt, and three reports of electric shock from a defibrillator.

In another case, a warning letter was issued in March 2000 to Thoratec Laboratories (Pleasanton, CA). The firm manufactures a ventricular assist device intended for use as a bridge to cardiac transplantation in patients with end-stage heart disease and for postoperative recovery. A January 2000 FDA inspection uncovered significant nonconformance with the quality system and MDR regulations. The list of infractions included the undocumented training of employees who perform activities related to electrical connectors, and a lack of specifications and verification activities for the parting strength of the connectors. "In addition to the QSR violations," the report stated, "Thoratec failed to advise FDA of at least two incidents under the MDR requirements for reportability, as it did not consider the incidents to be serious malfunctions."

To access the full FDA report, visit http://www.fdaweb.com/source/device.htm.

James G. Dickinson is a veteran reporter on regulatory affairs in the medical device industry.

Copyright ©2001 Medical Device & Diagnostic Industry

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