The Effects of Using Long Breathing Hoses Upon Mask Pressure.

摘要

Effects of using oxygen breathing hoses from 0.9 to 8.2 m (3 to 27 ft) long and mask fit upon mask pressure during decompressions from 2,438 m (8,000 ft) to either 6,096, 10,668, or 15,240 m (20,000, 35,000, or 50,000 ft) were determined. Peak mask pressures and duration of high mask pressure were related to mask fit, stretch compliance, pressure differential, Decompression rate, and other factors. Peak mask pressures frequently exceeded 80 mm Hg, a pressure associated with pulmonary damage. Cargo-type aircraft, however, have sufficiently large volumes so that they will not decompress rapidly enough to produce high mask pressures even with an 8.2-m long hose. Long breathing hoses should not be used in small cabin aircraft since the small volume will result in rapid decompression should cabin pressure be lost and consequently high mask pressures will result. Above 2,438 m, oxygen should always be breathed if hoses longer than 2.9 m (9 ft) are used. The fastest decompression rates compatible with preventing mask pressures from exceeding 80 mm Hg during decompressions to different altitudes with different length breathing hoses are given. (Author)