Originally Published MPMN July 2009
Gains in IV Customization Lead to Reduced Patient Pain
Smaller, stronger needles and cannulae can reduce patient pain and offer better insertion results
Contract manufacturer Tegra Medical offers a range of wire and tubular components and assemblies, including IV cannulae as small as 0.01 in. in diameter.
Concerns vary depending on whether a person is handling an intravenous (IV) device or is on the receiving end of one. Medical device manufacturers must consider both angles, as well as production factors. In order to provide surgeons and hospital professionals with IV products that accommodate their functional and safety requirements—and that reduce trauma to patients—medical device OEMs continue to require smaller, stronger, and more-complex needles and cannulae. To accommodate these needs, suppliers have improved their automated production equipment and enhanced their customization capabilities.
Smaller Device, Less Pain
Component size is playing a significant role in OEMs’ attempts to create products that minimize potential pain experienced by the patients being poked and prodded. “We have seen a trend where customers are asking for smaller IV cannulae, in some cases less than 0.01 in. in diameter, slightly larger than the size of a human hair,” says Will Lally, program manager for Tegra Medical (Dartmouth, MA; www.tegramedical.com), a contract manufacturer of complex wire and tubular components and assemblies. The company’s products are used in such applications as administration of chemotherapy and pain-management therapies via implanted IV ports. “The trend seems to be smaller-diameter needles that cause less trauma to the patient,” Lally says.
Such requirements are leading to an increase in customization of the size and tensile strength of these stainless-steel components, according to Frederick Hartman II, director of marketing for Vita Needle Co. (Needham, MA; www.vitaneedle.com). One reason that OEMs are increasingly specifying tensile requirements for their tubular products, he says, is that customers are finding that Type 300 series stainless-steel tubing, which is commonly used for less-complex components, can be less effective in applications in which high tensile strengths are required. The decrease in effectiveness is a result of the tubing undergoing fewer cold work sinks, which generally cause lower tensile strength, he says.
High tensile strengths are important because they allow for sharper needle points and increased overall durability. Using tungsten inert gas welding and a multiple cold-draw process, Vita Needle has been able to increase the strength of its stainless-steel tubing and needle assemblies. The company has made needles for diabetic blood sugar meter applications in which the components’ high tensile strength allowed for the formation of a very sharp needle tip, for example. Such performance characteristics result in reduced pain for the patient, Hartman says.
Automation and Customization
As device designs continue to decrease in size and increase in complexity, customization is becoming more popular than ever, requiring suppliers to be more and more flexible. “We believe that this stems from pressure to make devices perform exactly as designed by ensuring that the components are closer to their nominal design requirements,” says Hartman. Design engineers are selecting smaller tube sizes and thinner wall diameters while retaining the same complex features, especially when it comes to assemblies used in minimally invasive applications, he adds. One product that the company has worked on requires a thread to be tapped inside a tube with a 0.024-in. ID, for example. “This [trend] increases the pressure on manufacturers of these components to have advanced equipment and systems in place to comply with such requests.”
In order to produce the smaller, thinner, more-complex components that OEMs need, Vita Needle has increased its tooling capabilities and forming operations, including complex bends. The company has expanded its offerings of complex needle points and geometries to include such products as the Trephine, a tube primarily used in bone biopsies that is ground to a point on three sides, and the Menghini, which requires a primary bevel grind followed by a consistent-angle secondary grind along the outside of the entire cannula tip. It has also increased the percentage of tight-tolerance work that it performs using electrical discharge machining (EDM). “We can handle a greater degree of tight-radius bends, coils, and cold forming than ever before with additional plug-and-play tooling,” says Hartman. Automated specialty tooling also has enabled the company to improve its capability for producing flare tubes.
For small quantities of such complex components, manual assembling and forming operations are practical, but many OEMs need to move into high-volume production runs shortly after validation, Hartman explains. These specialized components tend to be made using exotic alloys. In addition, they feature complex geometries that must be produced on more-expensive CNC needle- and cannula-grinding equipment piece by piece instead of in bulk using traditional abrasive methods or electrochemical needle grinders. In the last year, Vita Needle has put together several automatic assembly machines to help its customers bring such products to market faster. One of the company’s needle-assembly machines can produce up to 10,000 miniature complete assemblies per day, for example.
Similarly, Tegra has made improvements to its automated equipment to increase the efficiency of its production methods for less-complex components. These parts include cannulae made from Type 304 stainless steel that are used to pierce tissue to introduce IV solution to the bloodstream. For high-volume production of such simple needle geometries, Type 300 series stainless steel will remain popular because of its availability and cost-effectiveness, Hartman suggests.
The CannuSeal system for cannulae and IV devices features two elastomeric valves that are designed to prevent losses in fluid and pressure.
For such applications as endoscopy and respiratory procedures, control of fluid and air pressure in cannulae and IV instruments is critical. This is especially true for procedures that require a surgeon or clinician to insert and remove an instrument to and from a patient multiple times, according to Justin Sessink, sales and marketing coordinator for Liquid Molding Systems Inc. (LMS; Midland, MI; www.lmsvalves.com). LMS has created a valve system specifically for cannulae and IV devices that prevents loss of fluid and pressure.
The CannuSeal system features two of the company’s MediFlo valves. When a cannula or IV instrument is inserted into the patient, the CannuSeal product’s first valve seals against the instrument so that there is no leaking when fluid or gas passes through the system’s second valve. When the instrument is removed, the valves reset in sequence to further prevent any fluid or air loss, explains Sessink.
Improving sealing features to cannulae, connectors, and docking areas also helps to decrease the risk of contamination, he adds. “The superior memory performance of certain elastomers plays a big role in the sealing features of the CannuSeal,” Sessink says. “That, in combination with proprietary slit configurations in the valves themselves, allows for accurate and consistent sealing against an instrument upon insertion and withdrawal. The plastic housing design plays a role by properly retaining the valves and aiding in the correct alignment of the instrument.”
LMS is aware of the increasing trend among OEMs to require customized cannulae and related components. Because of this trend, the company does not offer a standard off-the-shelf version of the CannuSeal system. “But we will integrate our features and design into a customer’s custom application,” says Sessink.
Copyright ©2009 Medical Product Manufacturing News