Hypobaric chamber
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A hypobaric chamber, or altitude chamber, is a chamber used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body, especially hypoxia (low oxygen) and hypobaria (low ambient air pressure). Some chambers also control for temperature and relative humidity.
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[edit] Procedure
One or more subjects (usually, pilots or crew members, though anyone interested in the effects of high altitude can usually arrange a visit) are placed in the chamber. Before "ascending" to the desired altitude, subjects pre-breathe oxygen from oxygen masks to purge nitrogen from their bloodstream so decompression sickness (DCS) does not occur. With masks in place, the atmospheric pressure inside the chamber is then reduced to simulate altitudes of up to tens of thousands of feet. The subjects then remove their oxygen masks and experience the symptoms of hypoxia. An inside safety observer, breathing oxygen by mask, should always be present to place a subject's mask back on in the event a subject passes out unconscious. Outside observers monitor the subjects' condition via closed circuit television and viewing ports.
While the mask is off, subjects may be asked to do trivial tasks, such as arithmetic and signing their own name. When such tasks start taking excessive lengths of time to be done or are done poorly, it is usually a sign that the "Time of Useful Consciousness" has been exceeded and that the mask should be replaced. Subjects may also insure that they are able to do tasks such as clear their nose and sinuses easily, as pain from such problems can be a major distraction in an emergency such as rapid decompression.
[edit] Use in Research
[edit] Use in Training
The primary purpose of the altitude chamber is for the subjects to determine what their hypoxia symptoms are. The symptoms of hypoxia are different for each individual, and this training is helpful for aviators to be able to recognize these symptoms during actual flight so as to avoid in-flight oxygen emergencies. Pilots who fly aircraft at altitudes in excess of 10 thousand feet (FL10) must use oxygen equipment. Altitude chamber training is required of U.S. military aviators every five years. The FAA and some larger airlines also require their pilots to periodically take altitude chamber training. Anyone with a pilot's license in the United States who has a current Class II medical certificate can normally sign up and receieve altitude training from the government.
[edit] Institutions with Hypobaric Chambers
- U.S. Army Institute of Environmental Medicine, Natick, MA, 33 years experience with its Hypobaric Chamber Facility
[edit] See also
- Hyperbaric chamber, an opposite device that places subjects under increased atmospheric pressure.
