As the COVID-19 pandemic spreads worldwide, there are critical concerns that hospital intensive care units won’t be able handle a surge in patients. A key limiting factor may be the number of ventilators a hospital has on hand to help the most seriously ill patients breathe.
New York City alone reportedly needs thousands of the breathing machines, which aren’t readily available in sufficient numbers. Medical manufacturers have ramped up production. General Motors, operating under the Defense Production Act, said it will deliver 30,000 units by August. Even companies like Dyson and Tesla are jumping into the fray.
But ventilators used in the U.S. are sophisticated, highly engineered machines that cost from $5,000 to $50,000 each, and they need a lot of specialized components from a wide range of suppliers — many of whom are offshore, short staffed or currently under lockdown.
As a pragmatic alternative, students at Rice University’s Brown School of Engineering created a basic device from off-the-shelf parts that supplies hospital-grade ventilation, yet only costs a couple-hundred dollars.
The fundamentals of ventilators are pretty simple. Coronavirus can cause inflammation in the lungs, which blocks membranes that transfer oxygen from the air into the blood. Bedside ventilators help push air into the lungs to open them up. The patient gets more oxygen and has the opportunity to stabilize and recover.
Last year, a senior team of bio- and mechanical engineering students working at Rice’s Oshman Engineering Design Kitchen (OEDK) designed and built a cost-effective device that automates the compression of manual bag valve masks. A BVM consists of a flexible air chamber that’s attached to a face mask. Squeezing the bag forces air through a one-way valve and into the lungs of intubated patients having difficulty breathing on their own. These masks have been used for nearly 70 years and are typically carried by emergency medical personnel. More than 100 million BVMs are manufactured around the world each year.
But masks are difficult to squeeze by hand for more than a few minutes at a time. The automated system can perform this task for hours. The students used a standard $25 motor and a $5 microcontroller to power and program the system. The unit’s “compressor” is a rack-and-pinion device made primarily of 3D-printed plastic parts with attached paddles that cyclically squeeze the bag. They anticipated the device would be useful in low-resource hospitals in developing countries, or during emergencies when portable ventilators are in short supply.
Now, with the COVID-19 crisis raging, requests are pouring into the university seeking plans for the early prototype. Staff at Rice’s OEDK quickly upgraded the student prototype into a more-robust ApolloBVM unit designed to be medical grade, and also economical enough to be considered disposable.
The ApolloBVM is built of some 3D-printed and laser-cut parts, but most components are readily obtainable through online retailers and hardware stores. That includes goBilda motors from Servo City, gears and fasteners from McMaster-Carr, and electrical parts from Mouser. Ambu makes the basic BVM. And an Arduino board, purchased off Amazon, facilitates programming that lets users adjust the rate of air delivery to patients.
The automated BVM unit was built for less than $250, a cost significantly lower than that of even entry-level commercial ventilators.
The device accommodates wall or tank-based oxygen through a standard low-pressure intake port. An LCD display lets users set the operating parameters and start or stop compression. Controls have adult, child, and pediatric settings that currently permit respiratory rates of 5 to 30 bpm (in 1 bpm increments), volumes from 300 to 650 ml (in 50 mL increments), variable positive pressure and adjustable inspiratory:expiratory ratios. The ApolloBVM is approximately 14 × 16 × 7 in. in size and weighs less than 10 lb, making it suitable for use on a portable bedside table. It is powered by 120 Vac with <15 W power draw.
Since Rice announced the team’s completion of a new prototype on March 27, hundreds of clinicians, engineers, manufacturers and do-it-yourselfers from more than 50 countries have requested information about the project. The open-source plans for the ApolloBVM have been posted online and are freely available worldwide.
The Department of Defense is one of the groups interested in ApolloBVM. The U.S. Navy invited several institutions to submit proposals to develop a low-cost, mechanical ventilation support system that can be rapidly produced with widely available resources. “This is as simple as it can get, with all readily available parts,” said Danny Blacker, OEDK’s engineering design supervisor.
With ongoing spread of coronavirus and a looming shortage of ventilators around the world, ApolloBVM could help COVID-19 patients who are less-critically ill while they await availability of a standard hospital ventilator. “The immediate goal is a device that works well enough to keep noncritical COVID-19 patients stable and frees up larger ventilators for more critical patients,” said Amy Kavalewitz, executive director of OEDK.
“This is going to make a difference in hospitals that run out of ventilators,” said Dr. Rohith Malya, an assistant professor of emergency medicine at Baylor College of Medicine and an adviser to the Rice engineering team. “Those that have relationships with a production facility that can quickly produce them should seek FDA emergency use authorization. We’re working locally to get that done.”
In lab tests with an artificial lung, the latest prototype delivered nonstop air for 24 hours, until the device was turned off. The next steps are testing with human patients in partnership with Texas Medical Center, and working with manufacturers seeking to ramp-up production of a hospital-grade device.
Oshman Engineering Design Kitchen