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MIDP students get creative to decontaminate respirator masks

May. 21, 2020, 8:58 AM


by Kelsey Herbers

Students from the Medical Innovators Development Program (MIDP) within the Vanderbilt University School of Medicine (VUSM) have devised a protocol that repurposes hospital blanket warmers to decontaminate N95 respirator masks — a process that could extend the current supply of the disposable masks by allowing them to be reused up to five times.

The proposed protocol comes in response to a global shortage of personal protective equipment for health care workers fighting COVID-19, who rely on the N95 masks to filter the air and prevent airborne exposure when working with infected patients.

The protocol was designed during a five-day COVID-19 Virtual Design Challenge organized by the Johns Hopkins Center for Bioengineering Innovation and Design. The MIDP team at Vanderbilt was one of 230 selected to participate out of 515 entries across 35 countries and consisted of six students from three different VUSM class years.

Students from the Medical Innovators Development Program participate in a Zoom call to discuss their protocol to decontaminate N95 respirator masks.

“The virtual aspect of the design challenge enabled over one thousand participants from across the globe to address problems caused by the COVID-19 pandemic. Locally, it provided an opportunity for us to overcome the difficulties of social distancing by coming together (virtually) and leveraging our diverse skillsets to address the unprecedented N95 mask shortage,” said Jess Wen, PhD, a fourth-year MIDP student who participated in the design challenge.

N95 masks are cleared by the Food and Drug Administration (FDA) and labeled as “single-use,” meaning they are intended to be disposed after each patient interaction. However, previous studies have shown that exposing SARS-CoV-2, the virus that causes COVID-19, to heat (56 degrees Celsius for 30 minutes) deactivates infectious virions, and that components in the mask are designed to withstand higher temperatures.

The protocol, dubbed the “Phoenix Protocol,” proposes assigning three N95 masks per provider — two of which would be used in a single shift and the third being available as a backup. Once the provider’s shift ends, the contaminated masks would be decontaminated through one hour of exposure to a dry heat of at least 60 degrees Celsius inside a hospital blanket warmer and stored until the provider returns for their next shift.

Under the protocol, masks could go through the decontamination process up to four times as long as they have not been damaged.

“Early in the pandemic, public health messages emphasized the importance of ‘flattening the curve’ of COVID-19 infections. By extending N95 mask use, we would be able to similarly ‘flatten the demand curve’ for N95 masks, providing more protection to the health care workforce who are vital for saving patients’ lives,” said Ariel Kniss, PhD, a fourth-year MIDP student.

The students propose a pilot study with 90 masks distributed among 30 providers to examine if heating can effectively kill SARS-CoV-2 on masks without compromising their effectiveness.

During the pilot, each mask would undergo fit testing at the beginning of the provider’s shift to ensure the respirator is still effective for use and to assess whether providers are receptive to disinfecting and reusing the masks. An expansion study would then examine whether the masks can be reused for more than four disinfection cycles, potentially further extending their lifespan.

If testing deems the protocol effective, it can be implemented immediately using existing equipment available at most hospitals. The solution is meant to extend the lifespan of the masks specifically for the COVID-19 pandemic and to serve as a bridge until more respirators become available.

Currently, when N95 resources are completely depleted at a hospital, health care providers can be forced to care for patients without appropriate protective equipment. Increased usage and demand for the masks is currently outpacing the supply chain to replace them, and hospitals may be left competing for resources.

“Specialized coursework and activities within the MIDP honed our problem identification and creative thinking skills. This empowers us to operate within constraints while developing novel and pragmatic solutions,” said Nicky Grimes, PhD, third-year MIDP student.

While federal regulations prohibit N95 manufacturers from instructing the public on how their product may be used in ways outside of their market clearance, the FDA does not regulate the practice of medicine, and hospitals and health care workers can exercise their best clinical judgement.

In addition to Wen, Kniss and Grimes, members of the MIDP team who created the protocol are Yongxu Huang, PhD, Adam Hetzler, PhD, and Hunter Sceats, PhD.

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