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Low-Profile Breathing Device for Improved Prebreathe Procedures

Nitrogen and oxygen are the two primary components of the air we breathe. Oxygen is used by the body, but we don't use nitrogen at all. Most of it is simply expelled from the body when we exhale, though some is absorbed into our tissues and blood. Under increased pressure, such as that experienced by divers, more air is forced into the body-including more nitrogen. Then, as the pressure decreases, that additional nitrogen must be exhaled. But if the pressure decreases rapidly, rather than being released from the blood in the lungs as a gas that can be exhaled, the nitrogen forms bubbles in the bloodstream, bubbles that cannot be exhaled but rather travel through the body, where they can block blood vessels, press on nerves, expand in muscle tissue, and create serious problems. The symptoms of the bends, so-called because of the body's response to the severe pain the bubbles can cause, vary from itching and swelling to difficulty breathing and muscle weakness to total paralysis, coma, and even death.

In the space shuttle, the pressure in a space suit is lower than the pressure in the cabin, and the pressure outside the craft is almost non-existent. Hence, the astronaut faces the same risk of decompression illness that a deep-sea diver does.

The solution for the astronauts is to exercise vigorously for about three hours, breathing pure oxygen from a mask as they do, to eliminate as much nitrogen from the body as possible before getting into the space suit. But the space suit is a tight fit, and the astronauts can't keep the oxygen mask on and get into the suit. They have to hold their breath while they finish putting on the suit and switch to the suit's oxygen; if they forget and breathe in cabin air, they have to sit in the suit and breathe from the oxygen mask for one-half hour before they can work outside the shuttle or risk getting the bends.

The solution, as envisioned by Dr. John Graf of NASA's Johnson Space Center , is a smaller oxygen mask, a snorkel, one that the astronaut can keep using until the helmet to the suit is sealed, at which point the mask can simply be dropped away into the suit. Students in the College of Technology have developed such a snorkel and are testing it in conjunction with NASA personnel.

Jesse performing a fit check

Another view of fit check

Michelle taking notes

CAD drawing of snorkelEarly SLA model - Manufactured courtesy of Hamilton Sundstrand

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NSF LogoThe Center for Life Support and Sustainable Living is funded in part through a grant from the National Science Foundation Advanced Technology Education program. Copyright 2008. All rights reserved.