Medical devices are everywhere. In a hospital, a patient is dependent on a ventilator to get the oxygen they need to recover. In a home healthcare setting, another patient suffers from sleep apnea and relies on a Continuous Positive Airway Pressure (CPAP) machine to sleep deeply all night long. The common denominator for each patient in these scenarios is the need for clean air, without high levels of harmful chemicals and particulates.
“Exposure to even low levels of chemicals could exacerbate the respiratory condition of some patients,” said Scott Steady, a product manager at UL Environment that specializes in air quality testing and GREENGUARD Certification. “That’s why it’s so important for companies manufacturing these medical devices to use the highest quality materials that can withstand heat and stress inside a machine but don’t release high levels of chemicals into the air inhaled by patients.”
UL’s GREENGUARD Certification program helps manufacturers demonstrate that their products have low chemical emissions – reducing indoor air pollution and aiding in the creation of healthier indoor environments. This program has established test methods and emission limits for interior products and materials including building materials, furniture and furnishings, electronic equipment, and cleaning and maintenance products. Expanding GREENGUARD Certification to include “breathing gas pathways” of medical devices is a natural extension of the program. GREENGUARD Certification for medical devices is based on the ISO 18562 series of standards for Biocompatibility Evaluation of Breathing Gas Pathways in Healthcare Applications,
Historically, medical devices with direct and indirect tissue contact, such as blood bags, needles and syringes that inject liquids into the body, went through vigorous toxicological review to assess the presence of potentially harmful chemicals that could enter the bloodstream. Only recently has the FDA started to request testing and evaluation of exposure through breathing gas pathways.
The FDA requirement applies to any medical device that delivers breathing air to a patient – from a hospital ventilator to plastic tubing delivering oxygen to a patient. These devices have the potential to emit harmful Volatile Organic Compounds (VOC) and particles into the air that patients are breathing into their lungs.
“A compromised medical device also poses a risk to the device manufacturer. If one of their products were to cause some sort of adverse effect resulting from chemicals in an airstream, they could face regulatory action or potential litigation,” added Steady. “Or if they measured and found toxic chemicals in their devices at the end of the development phase, it may not be cleared by the FDA, causing product development and delivery delays.”
The ISO 18562 series of standards – released in March 2017 – is a first-of-its-kind, harmonized standard for evaluating risk and exposure of harmful chemicals in a breathing airstream. The standards measure VOCs, particles and leachables in condensate in the air stream path.
“There are many components that make up a medical device. For a ventilator, there are touch screens, plastic cases, power supplies, valves and tubings – items that touch and don’t touch the breathing gas airstream. Companies that manufacture these devices are forced to make many supply chain decisions,” said Steady. “GREENGUARD Certification serves as a control system, offering a way to look at the contribution of all of the components so that manufacturers can make the changes they need, qualify the suppliers they have, and proceed with confidence knowing that all the medical device testing conducted meets a widely accepted standard.”
Testing a medical device for air quality starts with determining its usage. This includes determining whether to measure VOCs and/or particles, as well as how the device operates and at what settings (e.g: temperature or flow rate). Will the device be used by an adult, child or neo-natal patient? How will the device be used, where will it be used, how does it work, where does the air flow into the patient, etc.? Then, a test plan protocol is set up.
Once usage has been determined and the test plan is in place, the VOC and/or particle tests are conducted in environmental chambers supplied with purified air to introduce minimal contamination. VOC tests are performed for up to 7 days at elevated temperatures, about 40-50˚ C (104-122˚ F). High temperatures activate VOCs in the same way that overheated vehicles exaggerate that “new car smell” but the emissions typically go down with time.
Particles are tested for a one-day period and at standard temperature (23-25˚C) since elevated temperature may negatively affect particle test results. Particle concentrations are monitored in real-time using a laser particle counter to confirm if particle concentrations are increasing with time.
The VOCs are collected on absorbent media that are analyzed in the chemical laboratory to evaluate the compounds that are present in the air and at what levels. The data from the chemical analysis and particle test is then sent for toxicological review and compared with public health guidelines. If none of these chemicals are expected to have a toxic effect at the exposure concentrations, then the toxicology report will include a statement of minimal risk.
On average, the chamber testing of medical devices takes about four weeks, and the toxicology assessments take about two to three weeks. The tests may be conducted at any of several UL lab locations, including Atlanta, Georgia; Guangzhou, China; and, in the near future, Milan, Italy.