Collaborating to produce low-cost ventilators

Doctor holding oxygen over patients in ICU/Emergency Room

By Joe Feist

UT Health San Antonio researchers are collaborating with a team from The University of Texas at Austin to build a new type of ventilator made of inexpensive, widely available materials to help fill the demand created by the spread of COVID-19 for these critical devices that help patients breathe.

“There’s a shortage of ventilators nationally,” said Marc D. Feldman, M.D., professor of medicine in the Division of Cardiology and team leader at UT Health San Antonio. “A ventilator costs around $30,000, so there’s a need for a low-cost design alternative to fill this shortage.”

The UT Austin team is led by Thomas E. Milner, Ph.D., a professor in the Department of Biomedical Engineering. Drs. Feldman and Milner have collaborated on many projects for 22 years.

In the past few weeks, Dr. Feldman said, the two teams have participated in daily, lengthy conference calls to come up with a viable design. With such medical devices, he added, “engineers can’t work in isolation without clinician guidance, and clinicians can’t design and build these devices. A team approach is ideal.”

The researchers have come up with a device called the Assisted Bridge Breathing Unit, which uses a manual resuscitator, a common tool called an AMBU (artificial medical breathing unit) bag.

The AMBU is a handheld device approved by the U.S. Food and Drug Administration that includes a bag that fills up with oxygen and a mask that patients wear to receive ventilation. However, the unit requires a person to compress the bag frequently to help patients breathe, a challenging task at a time when medical personnel across the country are stretched thin due to the coronavirus. The team needed a way to automatically compress the bag to get oxygen to patients.

A windshield wiper motor pulled from a 2016 Toyota Camry powers a small caster wheel that pushes down on the bag to control oxygen flow. Four potentiometers control the respiration rate, the volume of oxygen given to patients, the time to inhale and the pressure applied.

“Essentially, we are replacing the human hand that would normally depress against the bag to inject oxygen into the patient’s lungs,” Dr. Milner said.

Another member of the San Antonio team is Richard Wettstein, M.M.Ed., associate professor/clinical in the Department of Respiratory Care. He and others, including Steven Derdak, M.D., are serving as clinical specialists in mechanical ventilation and have been bench testing the device for reliability and durability.

“We have utilized a variety of analyzers and sensors to measure function,” Wettstein said. “These have included oxygen and carbon dioxide analyzers, and pressure and volume measuring devices.”

Other members of the UT Health San Antonio team include Giles Cabe, Aleksandra Gruslova, Ph.D., and Allen Anderson, M.D., chief of the Division of Cardiology.

Dr. Feldman said the teams hope for FDA approval soon. The next step is to test the device on healthy pigs as well as pigs with adult respiratory distress syndrome.

“This could be a game changer that goes far beyond the current COVID-19 crisis,” he added. “There is a great need for low-cost ventilators in the Third World.”

But, he cautioned, “the last step is for scale up and mass production. Up to $250,000 is needed in initial start-up funds.”

A GoFundMe account has been set up at

UT Austin communications officers contributed to this story.

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