Researchers Modify Sleep Apnea Machines to Ease Ventilator Shortage

Researchers at New York University’s Tandon School of Engineering were able to modify continuous positive airway pressure (CPAP) machines, used to treat patients with sleep apnea, into alternatives for mechanical ventilators.

The team, led by Vikram Kapila, PhD, was able to modify CPAP machines by using readily available materials that can be assembled in minutes to adjust the machine’s function. Called the NYU Tandon AirMOD, patients using the system “wear a nonvented mask with filters that trap the virus when they exhale and keep it from entering the environment,” according to a press release.

Although CPAP and similar bilevel positive airway pressure (BiPAP) machines do not have the exact functionality of mechanical ventilators, researchers hope the alterations can help limit the number of patients with coronavirus disease 2019 (COVID-19) who need to be placed on a ventilator and conserve resources for the most severe cases.

The machines can be used as breathing support for both critical care patients being eased off ventilators and in individuals for whom the disease has not yet progressed to the point where ventilation is required.

Mechanical ventilators aid the breathing of patients with respiratory illnesses. A single machine can cost more than $50,000 and requires an invasive application process of inserting a flexible tube into the throat to fill the lungs with air. To effectively put a patient on a ventilator, patients must be sedated, paralyzed, and often require pain-reducing medications. Shortages of such medications have already been reported.

In contrast, CPAP machines can cost around $500, are a noninvasive treatment option, and already exist in most medical settings.

AirMOD modifications include viral filters, oxygen-enrichment adaptors, tee-connectors, and positive end-expiratory pressure (PEEP) valves. Modifications can be made to BiPAP machines, allowing for easier exhalation, or CPAP machines, which deliver constant positive air pressure whether a patient is inhaling or exhaling. In unmodified machines, pressurized air would amplify virus dispersion. The modifications effectively cut off the exhaust into the environment by filtering out the virus.

Clinicians raised concerns as to whether a mask secured on a patient’s face can prevent the spread of all virus particles. If, for example, a patient has a beard, the mask may not seal around all edges, allowing some of the virus to spread outside the mask. To address this issue, the same team of researchers developed the NYU Tandon AirVent.

This invention utilizes the AirMOD modifications to CPAP or BiPAP machines and combines them with a modified hair dryer hood commonly found in salons. By adjusting the hood to vacuum air instead of blowing it toward an individual’s head and adding a filter to trap the virus in the exhaled air and a plastic protective shield around the patient, the researchers hope this "negative pressure tent" can be used on patients in waiting rooms prior to diagnosis or during intubation processes.

The invention is, in effect, a downsizing of negative pressure rooms, which healthcare professionals already use to minimize the spread of airborne infectious diseases.

Jorge Serrador, PhD, an associate professor of pharmacology, physiology, and neuroscience at Rutgers University in New Jersey is currently conducting safety and efficacy testing for both inventions.

“I’ve tested whether CO₂ escapes the AirVent system or not, and shown that that doesn’t seem to happen” Serrador said in an interview with The American Journal of Managed Care^®. “I’ve been recently using a particle counter to check the .3 micron particles that the N95 masks are able to filter out...I want to see if this can do as good a job as the N95 masks,” Serrador said.

So far, testing has yielded positive reults. Using a fog machine to produce small enough particles and testing whether those particles go beyond the AirVent, Serrador found “we’re able to keep those really from going beyond. It all seems to be working at the moment.”

For now, Serrador awaits approval from the Institutional Review Board of Rutgers University to begin conducting human trials with the AirVent. The researchers have been in contact with producers willing to assemble around 200 units per day. “The advantage is we can immediately scale up production if we need to, without needing to…have specialized components built,” Serrador said.

Several hospitals throughout the country have adapted to the growing shortage of ventilator machines. At Mount Sinai hospital in New York City, one of the nation’s epicenters of the disease, doctors and respiratory therapists were able to convert a variable positive airway pressure machine into a functional ventilator. This modification, however, requires a 3D printed component that is not readily available in healthcare settings.

Kapila is working to secure expedited FDA approval for the modifications and ramp up production of PEEP valves, a component that might not be available in certain settings but is already regularly produced.

Advantages of the AirVent system include immediate isolation of patients upon entry to a healthcare facility, without exposing workers to potential spread. In addition, the AirMOD design “gives people the assistance they need in their natural breathing to maintain their oxygen levels while allowing their bodies to deal with the virus,” Serrador said. “Since [patients] are not intubated, they do not need to be sedated and can talk, clear their throats, and cough, which helps prevent pneumonia.”

He hopes that clinical trials will be able to answer questions about the modified machines’ functionality in patients. “If we could do a ventilation assist with the CPAP before patients go on the ventilator, can we give them enough support that their body can handle the virus, so they never get to the point that they need to get on a ventilator?” Serrador asked.

As for the team that thought of the modifications, Serrador admires their ingenuity. Most peoples’ first instinct when faced with a problem like this is to build something new, Serrador said. For the NYU team, they said, “Let’s not build something; let’s cobble together what we need from what’s out there to try to fix the problem.”