Specialty thermoplastics offer alternative medicine

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 non-compliant 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 post-market 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 provide innovative alternatives to traditional solutions, helping device makers stay ahead of impending government action and increasing pressure from the public.


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.

However, this exemption may be ending. Although the exact date has not been determined, it may be rescinded as early as 2012.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 utilizing 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, medical professionals, and even sensitive electronic components from tube leakage and room scatter. Thanks to its high density (specific gravity: 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 where 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. LNP Thermocomp HSG compounds from SABIC Innovative Plastics offer the potential for cost-effective, high-volume production, as well as greater design flexibility for new equipment configurations.

Avoiding the secondary operations required with lead, and gaining the freedom to consolidate multiple parts, can reduce total manufacturing time, system cost, and complexity. These benefits of LNP Thermocomp HSG compounds 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. Flexible Thermocomp HSG compound options allow designers to eliminate lead in applications such as protective X-ray gowns and curtains.


The Benefits of LNP Thermocomp HSG Compounds

• Proactive solution to upcoming enforcement of RoH requirements for medical devices;
• Shielding performance can surpass lead throug elimination of hot spots;
• System cost reduction is possible through high-volume molding vs. machining;
• Greater design freedom for differentiated products; and
• Available using a range of base resins.

Antimicrobial Plastics
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 two million people in the United States each year, resulting in 90,000 deaths and up to $6.5 billion in additional costs, according to the Centers for Disease Control and Prevention (CDC).1 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 nosocimial infections involve a medical device, such as a catheter, ventilator, or IV. As part of a multi-pronged 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, e.g., an indwelling catheter. For example, silver – a popular antimicrobial – releases ions at a steady rate as the metal oxidizes and provides protection at the surface.

Silver 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. This induces cell destruction and death. Silver can also disable a particular enzyme needed for oxygen metabolism, thereby killing the cell.

Importantly, silver and other antimicrobials are not the same thing as disinfectants, soaps, or other cleaners.

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, 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.

The goal is to produce a compound that incorporates the anti-microbial agent, eliminating the cost and time to apply a secondary coating or add a concentrate.


The Potential Benefits of Antimicrobial Thermoplastics

• Contribute to hospital patient safety strategies;
• Product differentiator that can command a higher price (offsetting the cost of the antimicrobial additive);
• Non-toxic and perceived as natural by consumers;
• Long-lasting performance; and
• Processing versatility.

Conclusion
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 hospital-acquired infections can help ensure better care at a significantly lower cost.

Patient safety is being advocated by the public, and mandated by government regulations, making it a top priority for medical device manufacturers and their suppliers and partners. By choosing new thermoplastics that incorporate protective agents – whether tungsten for shielding or silver for antimicrobial performance – device companies can stay out in front of public and regulatory demands, position themselves as forward thinking, and achieve other goals such as greater design freedom and improved manufacturing ease.

Although new regulations and industry trends may initially represent unwanted changes, innovative alternatives from the plastics industry can ease the transition and ultimately result in better healthcare products.


SABIC Innovative Plastics
Pittsfield, MA
sabic-ip.com

Authors: Tom O’Brien, Global Product Marketing Director, Healthcare, SABIC Innovative Plastics and David DeVito, Americas Specialty Products Industry Manager, Healthcare, SABIC Innovative Plastics