The Need for this Research
Rukshan Fernando
There is currently a renewed interest in the design of supersonic aircraft and other subsonic aircraft that will fly at higher altitudes (approximately 50,000 to 60,000 feet). These relatively higher altitudes hold the possibility of exposing passengers to greater degrees of hypoxia than in the current generation aircraft and therefore the Federal Aviation Administration (FAA) is interested in quantifying these risks. Primarily they are interested in creating a model with which they can predict permanent neurological damage in the event of a rapid decompression. There is a lack of data in this area and thus the current study was proposed. Decompressions from 8,000 feet to 25,000 feet were performed in two time periods: 20 seconds and 90 seconds. 13 Subjects were used and 22 decompressions were performed, 3 decompressions were aborted and out of the remaining runs nine were 90s decompressions and ten were 20s decompressions. Certain physiological parameters were measured continuously throughout the decompressions, these were: pulmonary ventilation, blood pressure, heart rate, oxygen saturation of haemoglobin and end-tidal partial pressures of oxygen and carbon dioxide. It was found that pulmonary ventilation rates did not change significantly, systolic blood pressure increased during the slow decompressions, heart rate increased in both decompression profiles, oxygen saturations dropped in both profiles, end-tidal partial pressure of oxygen reduced in a linear fashion with decreasing barometric pressure and end-tidal partial pressure of carbon dioxide decreased slightly. 2 Comparison between the two rates of decompression found that there was only one area where a difference occurred. This was in blood pressure, where systolic blood pressure increased in the slow decompression but did not do so in the fast decompression. All other measurements were not significantly different thus it was concluded that as far as this study was concerned the rate of decompression had next to no influence upon the measured variables. In conclusion further studies have to be carried out using higher final altitudes, as this is more realistic, a greater number of subjects and with a few more different rates of decompression. Ideally all the subjects should perform an equal number of each decompression profile. This study is set to become the first in a series of studies into this area.
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