Effects of altitude-related hypoxia on aircrews in aircraft with unpressurized cabins

Abstract

Introduction: Generally, hypoxia at less than 10,000 ft (3,048 m) has no apparent effect on aircrews. Nevertheless, several hypoxic incidents have been reported in flights below 10,000 ft. A recently introduced pulse oximeter using finger probes allows accurate monitoring of oxygen saturation (SPO2 ) in the aeromedical environment. Using such a pulse oximeter, in-flight SPO 2 levels were evaluated in aircrew in unpressurized aircraft. In addition, career inflight hypoxic experiences were surveyed. Methods: In-flight SPO 2 was measured in aircrews operating UH-60J helicopters at up to 13,000 ft, and 338 aircrew members operating unpressurized cabin aircraft were surveyed concerning possible in-flight hypoxic experiences. Results: In aircrews operating UH-60J helicopters, SPO 2 decreased significantly at altitudes over 5,000 ft, most markedly at 13,000 ft (vs. ground level). The survey identified three aircrew members with experiences suggesting hypoxemia at below 5,000 ft. Conclusions: Careful attention should be paid to the possibility of hypoxia in aircrews operating unpressurized cabin aircraft. Copyright © Association of Military Surgeons of the US. All rights reserved.