FLC | 50 years later, COVID-19 renews interest in Army respirator idea

50 years later, COVID-19 renews interest in Army respirator idea

April 14, 2020

As the world confronts the shortage of essential medical equipment caused by the COVID-19 pandemic, the internet buzzes with efforts to build makeshift ventilators, some based on the idea of a respirator invented by U.S. Army researchers more than five decades ago.

Among the many ideas and personal projects shared on internet forums, many people got excited over the design of a unique ventilator known as the Army Emergency Respirator. What caught their attention about this technology was that it could perform complex breathing-supporting functions without the need for any moving parts.

The Army Emergency Respirator has two configurations; a respirator with a moving bellows that takes over the intubated and sedated patient's breathing, and a simple breathing assist device to help the patient breathe easier through pressure augmentation. Army engineer Henrik H. Straub invented the device in 1964 while he worked at the Harry Diamond Laboratories, one of the seven facilities that merged to form the Army Research Laboratory in 1992.

The respirator represents one of the many important scientific milestones in the history of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, officials said. It uses the principles of fluidics to assist or control the ventilation of the patient. Much like how electronic circuit boards use wires and electronic valves to direct the movement of electrons and govern the system’s functions, fluidic devices use small jet streams that travel along a circuit board-like structure to perform analog and digital operations.

The apparatus named at the time the Army Emergency Respirator emerged as just one of many applications of this new breakthrough in fluidics. It connects to a breathing mask and automatically helps the patient inhale and exhale with a feedback loop that takes advantage of the changing pressures inside of the mask. When the air pressure inside the breathing mask is lower than outside the mask, the apparatus pulls in air from outside through a nozzle and carries oxygen into the patient’s lungs. Then, once the pressure inside the mask increases to a preset point, the apparatus automatically adjusts to help the patient to exhale, sending the air out through a different nozzle.

As a fluidic device, Straub’s invention didn’t require any moving parts. In fact, the laboratory’s prototype was only slightly larger than a pack of playing cards and consisted of a Lucite block with a system of intricate channels carved inside. However, its relatively simple design made it as a low-cost disposable tool for routine use at hospitals and clinics.

While Straub successfully tested his pressure-cycled respirator on dogs and human patients, the device remained in development as a working prototype and was never fully fielded by the U.S. Army. A similar model called the Fluidic Breathing Assistor was patented by the Bowles Fluidic Corporation in 1971, but Army research on the apparatus had been discontinued by the 1980s.

Despite having been confined to history for more than 50 years, the renewed public attention surrounding Straub’s invention gained momentum in last few weeks as independent technologists realized its potential – and discussed it on the internet – during this time of pandemic.

One engineer has already constructed an updated version of the 1965 ventilator and shared a video of the finished product on the social media website Reddit, prompting other users to look into the design as well.

The longevity of this one invention demonstrates how foundational knowledge created within the Army laboratories can lead to an impact that extends far beyond its originally envisioned applications, and over multiple decades, officials said.

Disclaimer: The U.S. Army Combat Capabilities Development Command’s Army Research Laboratory does not approve nor recommend any medical devices and has no position on any proposed applications of the Army Emergency Respirator for any purposes.