Research and Development of Anti-G Life Support Systems. Part 2. Decompression Sickness Research

Instrumentation and techniques for differentiating bends-prone and bends-resistant individuals were developed. Studies were conducted to determine bends- and bubble-formation altitudes using a variety of simulated pressure-suit pressures and breathing gas mixtures. A pressure of 9.5 psia eliminated the occurrence of bends under the conditions of these studies. In vitro studies of intravenous bubble formation were undertaken. United States Air Force USAF aircrews must be prepared to encounter loss of cabin pressure caused by either mechanical failure or deliberate maneuvering of aircraft. Aircrews generally tolerate short-duration depressurization well, but decompression sickness DCS occurs much more often than is reported. Symptoms of DCS range in severity from minor to life threatening however, all incidences of DCS require medical attention to preclude subsequent problems. The physiological mechanisms involved in DCS are not completely understood, but DCS is considered to result from supersaturation of body tissues with nitrogen N2. Supersaturation sets in as the ambient pressure hence the absolute pressure of N2 decreases. Nitrogen is less soluble in blood than in tissues so that the rate of decrease of partial pressure of N2 in tissues lags behind the rate of decrease in atmospheric N2 pressure, resulting in formation of N2 bubbles in blood and tissues. The tendency for bubbles to form is greater as the difference between the two pressure increases. The USAF School of Aerospace Medicine USAFSAM, Crew Technology Division, Space Applications Laboratory, conducted studies aimed at identifying susceptible individuals. Keywords Bands screening, Bubble formation.