Hospitals earned a bad reputation the last few years as places where accidents were more frequent than imagined and infections were easily contracted. It's not hard to find shocking statistics. The Association for Professionals in Control and Epidemiology, for example, says nosocomial (in-hospital) infections annually affect more than 2 million U.S. patients at a cost of over $5.5 billion. Obviously, the organization concludes, control and prevention can lower a patient's infection risk.

The manufacturers of IV components and materials have a few ideas for lowering the risk of accidents and infections with the introduction of antimicrobial additives to connectors and tubing, threaded connections that are unique to each medical gas, and filters with clever features inside and out. Hospitals may soon be less risky places to visit.

First, the filters

It's useful to those selecting filters to get an idea of why they are the way they are. For instance, it wasn't till the early 1980s that IV filters gained wide acceptance in the medical industry. “Before then, it was prohibitive to even think of an IV filter because there were no disposable devices,” says Mary Boomus, an engineer and VP of Healthcare Sales at GVS, Indianapolis, (gvs.com). “Most filtering was done with stainless-steel holders and removable membranes. Problems of the day included handling membranes, adsorption of drugs by membranes, and product sterilization,” she says.

The first IV filters, says Boomus, were 25-mm diameter, not vented, and made with cellulosic membranes. “It was thought at that time that a 0.45-µm pore-size membrane would sterilize solutions because of work done during WWII with potable water. However, we soon learned that 0.45µm membranes would not do the job. They would not remove Br. diminuta, an organism slightly larger than 0.2µm, so 0.2µm pore-size membranes became the material of choice. Later, with the development of polyethersulfone membranes, hospitals also had a filter media that did not absorb drugs.

At the same time, says Boomus, she and other engineers were developing vented IV filters. “The devices could then eliminate bacteria and particles along with air, which was a nurse's nightmare. Why? Because a large bolus of air can cause a stroke, and you could see air in tubes, so it was instantly gratifying to see air eliminated by a vent. The first vents were made with 0.2µm PTFE, but even these had a problem. After contact with vitamins in IV solutions, the vent would weep due to the surfactants in food supplements, compounds that make vitamins more easily absorbed.”

Boomus says she was the first to use 0.02µm PTFE in an IV vent, today's standard. “But that media size is quickly changing to 0.03µm because it allows faster air elimination while still not letting vents weep when used with surfactants. The current practice is to use 0.2µm polyethersulfone hydrophilic membrane with a 0.02µm or 0.03µm PTFE vent. Some people also use Kynar (polyvinylidene fluoride, or PVDF) vents. In addition to how fast air exits a filter housing, says Boomus, it's important that the filter membrane stay extremely hydrophobic in use. “Most membranes won't do this, but PTFE is the most hydrophobic on the market, so it works extremely well.”

IV filters are now tested for flow rates and adsorption of many different types of drugs, and must pass the ‘HIMA Challenge,’ which was a test first outlined by the American Society for Testing and Materials and HIMA (Health Industry Manufacturer's Association, now AdvaMed) in the 1980s. The test identified the parameters necessary to claim a filter as sterilizing grade. “A sterilizing grade IV filter must retain Br. diminuta at 10⁷ log-reduction value. Other important functions are that it must remove particulate and eliminate air from the solution,” she adds.

Other recent designs include 1.2µm filters for removing fungus from lipids (not possible with 0.2µm filters), and 5µm filters for removing particulate. A recent trend is to supply 15µm filters for tasks with immunoglobulin and chemo drugs.

Boomus adds that other products being developed include the swabable needleless injection site. These devices are important for protection of healthcare workers against needle sticks, which is more important today due to Hepatitis and AIDS (see OSHA 29 DFR Part 1910.1030. Occupational Exposure to Blood Borne Pathogens: Final Rule). Swabable needleless injection sites are used for adding drugs to main IV lines, as well as for aspiration solutions used in testing or administering drugs without contaminating the fluid path of a patient.

Tubes and fittings

Antimicrobial tubes and fittings are being recognized as one way to reduce in-hospital infections. “The medical market is embracing the use of silver as an antimicrobial additive in products,” says Marcia Coulson, president of Eldon James Inc., Loveland, Colo., (eldonjames.com). “We have developed new lines of medical tubing that feature low leachables and extractables,” she says. In addition, the company has products that are DEHP and plasticizer free. The additives to PVC make the material more manufacturable but are also suspected carcinogens, according to a list published in California's Proposition 65. “If a hospital is looking to move away from PVC tubing, one of several options include Flexelene Silver with silver as a lining to inhibit the growth of biofilm and bacteria,” says Coulson.

To allay the fears that there may be too much silver in the lines, Coulson says she commissioned tests to find a limit. “The test showed that water supplied from the tubing would require drinking 1,000 glasses in a day before the EPA says an unsafe level has been reached. So the silver is safe.”

In addition, some hospitals would like to incinerate tubing at their facility rather than having it hauled away. “So getting away from PVC also eliminates DEHP. We've found alternatives that are clear, flexible, and can be cleanly incinerated on site,” she adds. Eldon James' MFX, Medical Flexelene, is an example of the new tubing. It is made of a proprietary blend and can be manufactured with or without the silver lining.

With regard to safety features in company products, Coulson says the company worked with the Compressed Gas Association, Chantilly, Va., (cganet.com) to produce connectors for oxygen tanks. Association engineers designated threads for each type of medical gas. “So if a hospital uses the thread scheme, users won't be able to accidentally hook an oxygen line up to anything other than an oxygen supply,” she says.

Of course, it's not unusual for companies building IV sets to ask for unique designs for their applications. Most manufacturers are glad to assist. “We have developed molds with interchangeable inserts that go together like legos to allow manufacturing a range of custom products or unique designs for a fraction of what it would cost for custom tooling,” says Coulson.

Antimicrobial products, of course, cannot protect consumers from bacteria or other harmful agents that may be present in fluids. But by inhibiting microbial colonization on the surface of the tubing and fittings, new designs help control the formation of biofilms that can cause off-taste, odors, and deterioration of fluid quality.

Materials that inhibit bacteria

Antimicrobial materials are hot topics these days in light of the alarm raised by in-hospital acquired infections. Filters can do only so much. But designers can expect help from several sources.

One, a long recognized germ fighter, comes from Agion Technologies, Wakefield, Mass., (agion-tech.com) and the other, from Biosafe Inc., Pittsburgh, (biosafe.com). Agion says its product delivers silver ions in a 100% inorganic ceramic carrier which releases them through a controlled ion exchange. Silver ions at the surface of the product come in contact with bacteria and other microbes, disrupting the electron transfer and respiration within the cells. Silver is not toxic to humans and animals. In fact, the company says studies show the compound to be less toxic than table salt. The firm adds that antimicrobial-protected products are safe and effective enough for use in food and water-contact applications. The material is registered with the EPA and FDA recognized.

The release of silver ions, says the company, can be engineered to provide continuous antimicrobial protection for the life of a product. The silver antimicrobial is compounded into polymer resins to manufacture treated products providing integral protection. The antimicrobial compound works against a broad spectrum of bacteria, fungi, and other microbes. In laboratory studies, the material reduced bacteria on the treated product by as much as 99.999%, or a 5-log reduction. The company adds that silver has not been shown to contribute to the creation of ‘super bugs’, as has the overuse of antibiotics and other antibacterial agents.

IV component manufacturer Eldon James Inc., has been using the silver ceramic from Agion material in several products. The company's AG Fittings are aimed at biotech sciences, pharmaceutical, and many food and beverage applications.

A second antimicrobial material additive, from Biosafe Inc., is said to differ from others in that it forms a permanent covalent bond with the polymers in plastics and textiles.

The company says its material's advantages over standard antimicrobials include the prevention of adaptive or resistant organisms. “The additive kills by rupturing cell walls rather than being metabolized by the organism and interfering with its DNA,” says Biosafe VP of Business Development Donald Wagner.

In addition, the material contains no arsenic, heavy metals, polychlorinated phenols, or volatile organic compounds. Wagner recommends using material as a powder additive to polymers for plastics and textiles and has authorized compounder RTP Co., Minneapolis, (rtpcompany.com) to supply the antimicrobial in masterbatches. The product also comes in a form that allows use in sprays, dips, paints, and coatings. The material is registered with the EPA and listed with the FDA as a modifier for medical devices.

Biosafe's antimicrobial products are based on patents that describe interpenetrating polymer networks incorporating what they call organo-functional silane chemistry to impart permanent biostatic properties to the surfaces of many materials.

Filters for more than IV lines

Filters play a large part protecting patients and healthcare workers. “They can also protect hospital biomedical engineers from infection caused by suction systems, or hospital pharmacy workers from contracting cancer when mixing chemotherapy drugs,” says GVS Vice President Mary Boomus. Filters are used throughout respiratory therapy, chemotherapy, for immune-compromised patients, for isolation of patients from pressure transducers in open-heart surgery and hemodialysis, and even doctors wear suits equipped with filters in the OR to protect the environment from them and them from the environment.

In addition, the Millex HPF (High particulate filtration) line of syringe filters, from Millipore Corp., Billerica, Mass., (millipore.com) is said to improve throughput of high particulate and viscous solutions. The filters are available with a recent hydrophilic Teflon membrane, which has the broadest chemical compatibility and lowest extractability of any membrane, according to the company. When used to filter samples and liquid buffers, Millex filters are said to improve the consistency of results, sample throughput, and the longevity of expensive analytical equipment.

The filters use a glass fiber prefilter and a membrane filter. Hydrophilic Teflon and nylon Millex HPF filters come in 0.2 µm and 0.45 µm pore sizes. The company says the low-analyte binding and low-extractable characteristics make the filter useful for applications such as drug dissolution testing and chromatography sample preparation.

Barcode programming improves IV medication safety

IV pumps have gained wide acceptance in hospitals because they are more accurate than gravity flow and built-in safety features, such as a host of alarms that let nurses know when something is amiss. But programming an infusion pump often was seen as complicated and had nurses referring to reference guides when they used these devices infrequently. Adding to the complexity is that every brand of IV pump has a different programming sequence. Mix in a heavy work load with more patients assigned to each nurse, and it's easy to see how infusion devices become a source of medication errors in the clinical setting.

One impetus to reduce errors has been the recommendation by a joint commission to reduce the number of concentrations of a drug and to standardize concentrations across the hospital practice. Reducing the number of concentrations available for any given drug reduces the chance of a dose error. However, standardizing concentrations doesn't address the possibility that the wrong medication could be administered to the wrong patient.

“Bar-coding has been one way to verify that the right patient gets the right drug,” says Joel Bartholomew, manager, OEM/International R&D at B. Braun Medical Inc., Allentown, Pa. (bbraun.com). “One innovation adds barcode scanning to the infusion pump. The nurse scans the patient's ID on the wristband and then the patient ID on the medication label of the IV bag. If there is a mismatch, the pump alarm sounds. If the hospital prints the entire IV prescription on the bag label, it is also possible to scan this information into the pump and nearly eliminate all manual programming steps. The nurse then only needs to confirm the information and start the pump. This not only saves the nurse a little time but more importantly, it reduces medication errors,” he says.

A brief filter nomenclature

Hydrophobic	Filters that repel water and generally cannot be wet by aqueous solutions without high pressure or by first wetting them with a low-surface-tension liquid. The designs are generally used for gas filtration, or venting, or both.
Hydrophilic	Filters that can be wet with any liquid and are generally used for liquid filtration.
Oleophobic	Recent specialty filters for venting containers of liquids containing lipids, fat emulsions, multi vitamins, and oils.
Extractables	The term applies to the phenomenon in which fiber binders, surfactants, and other substances in media production leach out and contaminate a drug being filtered.
Nominal pore size	The value defines the ability of the filter media to retain most of a particulate equal to or greater than the rated size.
Absolute pore size	This is the absolute and total retention of the challenge medium whether a particulate or organism.