Originally Published MPMN September 2005
Keeping It Separated with Filters and IV Components
Fabric and metal filters reduce contamination risks in medical devices
Many medical applications require specialized filtration or screening products. According to Larry Loff, senior territory manager at Sefar America (Depew, NY; www.sefar.us), filters are still primarily made using traditional fabrics, but research on alternative materials continues. "In order to make a filter out of a particular material, its fibers have to have strength, elongation, and weavability," says Loff. PEEK is still under development as a woven fabric, he adds.
Filtration products, as well as materials for use in IV equipment, are featured below.
Membranes and Fabrics Filter out Toxins
|W.L. Gore & Associates Inc. manufactures a medical membrane to filter out pathogens found in smoke and aerosolized fluids.|
Several companies offer materials that are designed to filter out toxins such as smoke and bacteria. Sefar America’s Medifab fabrics meet the strict cleanliness requirements of the medical industry and are routinely tested for endotoxins and hemolytic substances. USP Class VI, ISO 10993, and cytotoxicity tests are performed regularly. The fabrics act as security filters and as wicking and spreading media in such products as infusion and transfusion sets, arterial and cardiotomy blood filters, blood bags, dialysis sets, and diagnostic test strips. Surface treatments, including hydrophilic and hydrophobic coatings and plasma, are available for Medifab fabrics to enhance priming, wetting, and wicking properties.
A medical membrane is designed to prevent breakthrough of pathogens found in smoke and aerosolized fluids. W. L. Gore & Associates Inc. (Elkton, MD) offers the Gore medical membrane for surgical smoke filtration. The product’s all-in-one design combines high particle-holding capability and long life with a robust contamination barrier to provide protection to health-care workers, patients, and equipment. It is suitable for filtration applications in both laparoscopic and invasive procedures.
The membrane is a multilayer laminate combining a microfiberglass prefilter to trap smoke particles and a hydrophobic PTFE membrane to contain bulk liquids and provide fine filtration of smoke and aerosols containing bacteria and viruses. The prefilter also significantly reduces clogging of the PTFE membrane by smoke, allowing strong suction to be maintained throughout the surgical procedure. The all-in-one design eliminates the need for separate coarse and high-efficiency filters, making new device designs simpler and more cost-effective.
Available in a variety of product forms that can be adapted to existing or new designs, the membrane is readily processed in automated manufacturing environments.
Adult IV Filters Are Self-Priming
|Adult IV filters from
Qosina are self-priming
and come with a choice
of tube or socket ports.
Self-priming and positively charged adult IV filters from Qosina (Edgewood, NY) allow for a flow rate of 25 ml/min at 36-in. water head height. Each HiFlo filter has a polyethersulfone (PES) hydrophobic membrane and a PTFE hydrophobic vent. Made from an alcohol- and lipid-resistant modified acrylic, the housing allows for visual clarity during use. The filters come with a choice of tube or socket ports that eliminate the need for adapters or fittings. The self-priming 0.2-µm filters have tube ports with a 0.120-in. OD, and are also available with 0.150-in.-ID socket ports. The positive-charged 0.2-µm filters come with 0.120-in.-OD tube ports or 0.150- in.-ID socket ports. The company stocks more than 70 filters, as well as connectors, drip chambers, spikes, injection sites, tubing, and bags.
Miniature Filters Offer Precise Flow Control
|Bird Precision offers miniature connectors for use in liquid and gas flow control.|
Miniature orifice and filter connectors from Bird Precision (Waltham, MA) can be used for precision flow control of liquid and gas. The connectors are available in orifice sizes from 0.0004 to 0.035 in. with standard filtration level offerings of 5, 25, and 43 µm. The company also offers 1/16 NPT barbed orifice connectors and 3-56 thread to 1/16 barb connectors.
Microscreen filters using a stainless-steel wire mesh are also available from the firm. This type of product allows for the least amount of back pressure because of the open area, as opposed to other more restrictive types of filtration media. Wire mesh filters are available in 5, 10, 25, 43, 73, and 100 µm. Other filter media currently used by the company are porous plastic, PVDF, sintered bronze, plated sintered bronze, and plastic mesh.
Adaptable Stopcock Replaces Three-Port Models
A stopcock allows for one-handed IV injections. The Twist-N-Ject stopcock from G L Medical (Beverly Hills, CA) is a four-way, four-port unit that can replace three-port models. To use the stopcock, a fluid-filled syringe is attached to the axial port located on top of the lever. The syringe barrel is then twisted to point the lever toward the desired port, and the fluid is injected.
Fluoropolymer Tubing Provides Versatility
|Fluoropolymer tubing from TexLoc Ltd. is suitable for use in several types of fluid- and material-handling applications.|
Fluoropolymer tubing products that are extruded from TexFluor PTFE, FEP, PFA, or MFA in a variety of configurations can be supplied with fittings. TexLoc Ltd. (Fort Worth, TX) has introduced the line of precision fluoropolymer tubing. Featuring a low coefficient of friction and antistick properties, each material has specific dominant characteristics. All materials are chemically inert, nonwetting, and nonleaching, making them suitable for a range of fluid- and material-handling applications. Offered in sizes from 0.004- to 4-in. ID, the tubing can operate at up to 500ºF.
Depending upon the material and configuration, the tubing can be supplied with compatible fittings or formed with flares, tips, or chamfers. The tubing provides unrestricted flow and is available with a low refractive index for applications where operators must visually monitor materials passing through the tube.
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