Medical invention feeds air to lungs

Natalie Dickman repeatedly squeezed the bag to revive a victim of cardiac arrest. After 3 minutes, the Rice University student couldn’t squeeze any more.

“The patient had been down for 30 minutes and there wasn’t much hope, unfortunately,” says the Rice University studen, a soon-to-be graduate of the Brown School of Engineering who was covering a shift with Houston EMS for a class in emergency medical techniques. “I was allowed to bag, but they make you switch in EMS settings because they know you won’t be as accurate once you hit that 2-to-3-minute mark. You get really tired.”

She thought about that often when she and her senior teammates worked at Rice’s Oshman Engineering Design Kitchen (OEDK) to develop a cost-effective device to automate compression of manual bag valve masks.

The senior capstone design team known as Take a Breather includes bioengineering students Dickman, Carolina De Santiago, Karen Vasquez Ruiz, and Aravind Sundaramraj; mechanical engineering and computational and applied mathematics student Tim Nonet; and mechanical engineering student Madison Nasteff.

The team developed a system that compresses bags for hours, rather than minutes, with settings to feed the right amount of air to adults, children, and infants. The device seems simple – a box with paddles that rhythmically squeeze the bulb a programmed amount – but the engineering behind it is not.

The students used a $25, off-the-shelf motor and $5 microcontroller to power and program the rack-and-pinion device, made primarily of plastic parts 3D-printed at OEDK. They hope their use of inexpensive materials and the growing availability of 3D printers will make their machines easy to repair on-site.

They anticipate the device, which cost them $117 in parts to build, will be most useful in low-resource hospitals or during emergencies when there aren’t enough portable ventilators to meet the need.

The device is much smaller than sophisticated ventilators found in hospitals and portable versions used in emergency situations. It must operate for long stretches, and in its most recent test, the team ran the device for more than 11 hours without human intervention.

The students expect another Rice team will build a more robust version next year and hope it will eventually be manufactured for low-resource and emergency settings. They anticipate a better-sealed and filtered box will be more suitable for hot, dusty environments, and said future designs should include more sophisticated controls.

Rice University