Originally Published MPMN April 2002

PRODUCT UPDATE

Filters and Valves Get Stronger, Smarter

Suppliers focus on making components more durable and user-friendly

Zachary Turke

Regardless of the application, filter and IV components share many of the same requirements. Used in the often-hectic environment of healthcare facilities, both types of products must be simple to operate, posing no risk to either patient or physician. They must be durable enough to withstand extended use and exposure to a wide variety of fluids. Biocompatibility, processibility, and sterilizability are just a few of the other shared concerns.This article discusses recent advances in filter and IV components that help meet these challenges.

Valve eases guidewire placement

A hemostasis valve offered by Qosina that can be operated using one hand may not "help surgeons grow a third hand," quips product manager Jim Pimpinella, "but its unique design achieves the same effect by simplifying the task of guidewire placement." The device has a thumb-activated handle instead of the standard twisting cap; it rests in the palm of one hand, and allows wire placement with the other. When the desired position is achieved, the user simply flips the valve handle to lock the wire in place without releasing the valve body.

Suited for angioplasty and catheterization applications, the one-handed valve features a clear polycarbonate body to allow visual identification of bubbles. A nylon handle, silicone gasket, and rotating male luer lock with a silicone O-ring are cited as additional construction benefits. With a large inner diameter, the valve accommodates devices up to 8 french and closes completely when activated.

While it doesn't promise surgeons the benefits of an extra hand, a needle-free capless valve from B. Braun Medical does help to ensure that the two hands they do have remain free from accidental needlesticks. Meeting guidelines set forth under the Needlestick Safety and Prevention Act, the Ultrasite valve features a redesigned housing that allows access by syringe or IV tubing without the need for additional components. "Furthermore, the safety features on the bidirectional valve can't by bypassed," says marketing associate Wendy Achey.

Designed with full threads for a tight connection and a stop ring to prevent overtightening, the valve uses a positive-pressure design that inhibits catheter occlusions. The component is constructed of latex-free materials and is lipid resistant. "It doesn't require a sterile cap," adds Achey. "Just give the valve an alcohol swabbing and it's ready for use." Available in y-site, in-line, extension set, and dispensing pen versions, the valve is suited for the intermittent injection, aspiration, or infusion of fluids.

New generation of filters stand up under pressure

Filters are used in a variety of procedures to prevent contamination and ensure sterility, but these products are often too fragile to remain in position without a support membrane. To solve this problem, plastic sheets of varying thickness are often employed to add the needed strength. The addition of this component, however, can present manufacturers with a new problem: separation of the filter media and support substrate caused by poor adhesion. A new generation of filter assemblies uses improved lamination techniques to increase peel strength and eliminate this problem.

One such product is the Emflon PTFE filter media offered by Pall Corp. Supplied with 0.2–1-µm polyester or polypropylene supports, this material is produced with a proprietary laminating technique that ensures a strong bond. "Our special laminate greatly increases peel strength so the media card and backing don't separate, even when the material is processed on high-speed manufacturing equipment," says marketing associate Sam Mamo.

Offering a barrier to microbes and particulate matter, the filter membrane also features a consistent thickness and reproducible airflow characteristics. The bacteria-retentive material repels liquids while creating a sterile pathway for air. Sample applications include transducer protection, bag vents, and suction canisters. Wide processing capabilities are among the other benefits of the Emflon material, according to company reports. The membrane is compatible with adhesive bonding, heat and mechanical sealing, and insert, heat, and RF welding. Acceptable sterilization methods span gamma, E-beam, EtO, and steam processes. Satisfying USP Class VI requirements, the media withstands temperatures up to 500°F and exposure to aggressive solvents, acids, bases, and organic chemicals.

Precut polystyrene and polyester diagnostic cards from Adhesives Research Inc. use a special adhesive to promote better bonding. Applied in a thickness of 1 mil, the medical-grade acrylic is rigid enough to support the bonded components, but remains sufficiently flexible to allow die-cutting without gumming. The adhesive also reduces creep into the filter membrane, allowing for more-accurate testing by eliminating flow interference.

Suited for lateral-flow diagnostic tests, the Arcare 9020 and 9021 cards feature white substrates that increase assay visibility. Both substrate cards have flat surfaces that bond to membranes without producing buckles. The devices are available in custom sizes and can be ordered with prescored liners that ease removal. Uniform flow characteristics and membrane capillary channels that resist constricting are cited as additional product benefits.

Supplied by Filtertek Inc., a disposable bypass prefilter that uses nylon supports removes undissolved solute particles and airborne bacteria from extracorporeal cardiosurgery circuits. "The blood-contact components used in these kinds of support systems contain thousands of particles. They can be removed by this filter, significantly reducing the risk of embolization," says program manager Jeff Close. The filter employs an acrylic copolymer membrane that features an effective filtration area of 10.8 sq in. and has pore sizes of 0.2 or 5 µm. A clear housing improves visualization and accommodates tubing with inner diameters of 3/8 to 1/2 in. All component materials meet USP Class VI test requirements. A flow-direction arrow and restriction notes are molded into the unit's housing to ensure proper usage.

A different kind of membrane support is offered by Filtrona Richmond Inc. The company's prefilter media processes the filtrate before it reaches the filter, increasing filter strength and life by removing coarse particulates that could plug, surface bind to, or otherwise damage the filter membrane. Available in acetate, nylon, and polyester, the media is constructed without resin or adhesive binders to reduce the possibility of contamination. A range of cross-sectional sizes and shapes are available to provide consistent performance. Typical applications include heat and moisture exchange, centrifugal platelet separation, and blood and mucus evacuation.

Copyright ©2002 Medical Product Manufacturing News