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Inventor of ‘Negative Pressure Helmet’ for COVID-19 Battle Searching for Manufacturing Partners

Kip Hanson
By Kip Hanson Contributing Editor, SME Media

Sridhar Kota, a professor of mechanical engineering at the University of Michigan, is looking for manufacturers to produce en masse a “negative pressure helmet” he invented to prevent intubation and “help provide a more positive outcome for thousands of (COVID-19) patients and healthcare workers alike,” he said. To support this effort, the University of Michigan is willing to provide non-exclusive (and free) licenses to anyone who can produce the AerosolVE helmet during the pandemic, even though it has filed for a provisional patent on the device, he added.

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Dr. Kevin Ward, professor of emergency medicine at the University of Michigan, tests the AerosolVE helmet that Sridhar Kota, a professor of mechanical engineering at the school, invented.

“We need manufacturing partners, and we need them now,” said Kota, who can be reached at “If you're currently making PAPRs (powered air-purifying respirators) or similar equipment, you can easily make our negative pressure helmet: It’s largely a matter of reversing the airflow through the filter. A simple, 3D-printed shroud on the inlet side of a conventional PAPR allows it to connect the helmet hose to pull air through a HEPA filter. There's nothing more to it than that, but we need to scale up quickly.”

Med student has lightbulb moment

Like many great ideas, this one started at the kitchen table. One evening in late March, Kota was talking to his daughter about an email he’d received from the school’s medical research center, Michigan Medicine. In it, physicians challenged the university’s College of Engineering to find a system for containing the spread of aerosolized virus from COVID-19 patients, and Kota figured what better person to brainstorm with than a first-year medical student.

“We were discussing how intubation is very risky for patients, and that one of the preferred treatment methods is a high flow of heated oxygen delivered through a nasal cannula,” he said. “The problem with that is the increased aerosolization of the virus, which can be very dangerous to healthcare workers. Negative pressure rooms are one way to contain it, but they are quite expensive and there are very few available, so it's not a scalable solution. Also, they allow the virus to spread throughout the room, further increasing the risk to others. That's when she said, ‘Why not use a helmet, like they have for astronauts, but filter the air coming out of it?’”

Kota and his daughter then discussed how they could create a personal negative pressure room by attaching one end of a hose to the helmet and the other to a vacuum motor and HEPA filter. Further, they would use only the rigid front half of the helmet—the section with the movable face shield—and then wrap a soft plastic around the rest to cover the back of the patient’s head, neck and shoulders.

The conversation lasted about 15 minutes. The pair was left wondering if the solution could really be this simple.

Sridhar Kota

The next morning, Kota reached out to Dr. Kevin Ward, professor of emergency medicine at the university. Ward felt the idea had merit, and he offered to test the helmet if Kota could pull together all the pieces needed to build one.

Assembling airways

As it turns out, assembling those pieces was not as difficult as initially thought. Kota soon found a far less expensive and more readily available alternative to retro-fitting an astronaut helmet: an industrial, positive-pressure hood like those worn by welders, painters and firefighters—an item he was able to procure the next day.

“All we had to do was reverse the flow,” Kota said. "For that, we used a motor from a vacuum cleaner I picked up at a local store, then connected it to the opposite end of the helmet. The concept is similar to a PAPR (powered air-purifying respirator) except that we use a vacuum to draw ambient air in through the bottom of the helmet, force it through a HEPA filter, then discharge the now purified air back into the room. It's such a simple, obvious idea, but one that we’ve since found is shockingly effective.”

Kota delivered the newly dubbed AerosolVE helmet to Ward, who immediately tested it on himself and other physicians before using it on COVID-19 patients in an emergency room. With a supply of up to 60 liters of oxygen per minute through a nasal cannula, the vacuum motor draws over 300 liters per minute of exhaled air and room air through a loosely fitted shroud, providing 22X the air exchange of a negative pressure room for less than 1% of the cost.

Validating the design

The results, he said, were spectacular. “Everyone loved it. It’s comfortable, you can talk to others while wearing it, and most importantly, the helmet delays and in some cases eliminates the need for a ventilator and painful intubation. It also draws enough air that medical staff can open the face shield and treat the patient without worrying that air exhaled by the patient could escape from the front. Emergency room physicians told me the helmet would allow them to turn every bed into an ICU (intensive care unit) bed and even treat patients in the hallways if needed. It’s that effective."

Dr. Benjamin Bassin, assistant professor of emergency medicine and director of the Emergency Critical Care Center at Michigan Medicine, agreed.

“This is a creative solution that has been re-engineered to protect health care workers, spare ventilators and allow therapies to be delivered outside of negative pressure rooms,” he said. "Based on the patient encounter and testing to date, it does what it was designed to do and has been an overwhelming success.”

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