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Specialty plastics help device makers get ahead of patient safety regulations, trends

The RoHS lead replacement exemption is likely to end soon. The public and insurers are focusing more on hospital-acquired infections. Can specialty plastics help device makers cope? In a word, yes.


Patient safety continues to be a top concern in the healthcare industry. Whether the issue is reducing hospital-acquired infections (HAIs) or avoiding exposure to toxic substances, government agencies are bringing to bear a number of weapons to improve safety rates. These range from regulations restricting hazardous materials to reductions in reimbursement for noncompliant care providers.

At the same time, consumer pressure plays an important role in fueling trends such as greater transparency regarding the drug and device approval and postmarket surveillance processes—both critical to ongoing safety efforts.

Two important issues regarding patient safety—lead replacement and antimicrobials—are prompting medical device manufacturers to search for new materials. In both cases, specialty thermoplastic resins and compounds can provide alternatives to traditional solutions, helping device makers stay ahead of impending government action and increasing pressure from the public.

Lead replacement loophole is closing
When the Restriction of Hazardous Substances (RoHS) directive went into effect in 2006, limiting the use of lead and five other materials in electrical and electronic products, the European Union (EU) recognized that medical devices (RoHS Category 8 products) represented a very small percentage of affected products. Further, these devices are often used in mission-critical care applications where their failure can be extremely disruptive, if not catastrophic.

In view of the small number of products involved and their high potential risks, and because replacement solutions for lead solder and lead shielding were inadequate or unproven at the time, the EU established a moratorium on compliance with the RoHS lead restrictions for Category 8 products.

This exemption may be coming to an end. Although the exact date has not been determined, it may be rescinded as early as 2012. Therefore, manufacturers of medical devices and packages that utilize lead shielding—including x-ray and radiation therapy equipment, fluoroscopes, collimators, and drug therapies using lead containers—need to begin considering other solutions. As an added incentive, China is intending to mirror the EU directive in its own “Management Methods for Controlling Pollution Caused by Electronic Information Products Regulation” (usually called “China RoHS”). Therefore, enforcement by the EU may well be echoed by China.

Medical equipment and devices that produce x-rays and gamma rays must be shielded to protect patients, technicians, and medical professionals, as well as sensitive electronic components from tube leakage and room scatter. Thanks to its high density (specific gravity of 11.35), lead absorbs radiation and has been used for medical and dental equipment shielding for years. Lead also offers affordability and ease of fabrication. However, in addition to its health and environmental concerns, lead shielding is difficult to design with and can have hot spots through which radiation can penetrate. 

Other metals and alloys such as tungsten, tungsten alloys, and molybdenum alloys have been investigated as possible lead replacements, but they lack lead’s manufacturability. By combining a metal with injection moldable thermoplastics, this manufacturing hurdle may be overcome.

The leading lead-replacement approach uses tungsten fillers in a resin matrix to create high-specific-gravity (HSG) compounds that effectively block radiation. These compounds can be engineered to provide the same specific gravity as lead for equivalent radiation shielding performance, while providing consistent coverage to avoid hot spots.

Avoiding the secondary operations required with lead and gaining design freedom to consolidate multiple parts can reduce total manufacturing time as well as system cost and complexity, which can compensate for the low cost of lead. A key potential design advantage lies in new technologies that are being used to create flexible, elastomeric grades.

Additional benefits of the HSG compounds include more design freedom to create differentiated products, cost reduction from volume molding vs. machining, and that the compounds can use a range of base resins.

Antimicrobial plastics combat HAIs
While lead shielding is typically confined to the radiology, nuclear medicine, and radiation therapy departments of a hospital, infections can be acquired throughout the facility. HAIs (also called nosocomial infections) affect nearly 2 million people in the United States each year, resulting in as many as 90,000 deaths and up to $6.5 billion in additional costs, according to the Centers for Disease Control & Prevention (CDC). Further, the incidence of “super bugs” such as MRSA, C. difficile, Vancomycin-resistant enterococcus, and drug-resistant Acinetobacter is on the rise.

Hospitals are challenged by the public and insurance companies to reduce these infections. For example, in 2008 the Centers for Medicare & Medicaid Services began reducing reimbursements to facilities for “hospital-acquired conditions” that include catheter-associated urinary tract infections, vascular catheter-associated infections, and surgical site infections.

An estimated 50% of nosocomial infections involve a medical device, such as a catheter, ventilator, or IV. As part of a multipronged prevention strategy, hospitals are looking at purchasing devices featuring antimicrobial agents. These agents can provide continuous protection against infection, which is particularly important when a device is used over an extended period—for instance, an indwelling catheter.

Silver—a popular antimicrobial—releases ions at a steady rate as the metal oxidizes and provides protection at the surface. It works by interrupting ribonucleic acid (RNA) replication by the microbes that ingest it, thereby preventing them from reproducing.
Positively charged silver ions attach to negatively charged bacteria cell wall sites and destroy cell wall permeability, which then induces cell destruction and death. Silver also can disable a particular enzyme needed for oxygen metabolism, thereby killing the cell.

Incorporating silver into thermoplastics is a promising solution for antimicrobial medical devices. Not only has silver been used and tested over a number of years, but also it is perceived as “natural” by consumers. Silver can be provided in a finished compound, added by the compounder as a concentrate, or applied as a secondary coating. Importantly, silver and other antimicrobials are not the same thing as disinfectants, soaps, or other cleaners.

The goal is to produce a compound that incorporates the antimicrobial agent, eliminating the cost and time of applying a secondary coating or adding a concentrate. Such a solution is nontoxic and considered natural by consumers, is long-lasting, offers process versatility, and becomes a product differentiator that can command a higher price that offsets the cost of the antimicrobial additive.

The twin healthcare goals of cost reduction and improved patient outcomes are both intimately tied to better safety. Avoiding risks to patients and caregivers from lead exposure and HAIs can help ensure better care at a significantly lower cost. By choosing new thermoplastic compounds that incorporate protective agents, device companies can stay out in front of public and regulatory demands, position themselves as forward thinking, and achieve goals such as greater design freedom, improved manufacturing ease, and overall better healthcare products. —Edited by Rob Neilley

Tom O’Brien is global product marketing director, healthcare and David DeVito is Americas specialty products industry manager, healthcare, Sabic Innovative Plastics.

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