Early Human Pathophysiological Responses to Exertional Hypobaric Decompression Stress.

Consistent blood biomarkers of hypobaric (altitude) decompression stress remain elusive. Recent laboratory investigation of decompression sickness risk at 25,000 ft (7620 m) enabled evaluation of early pathophysiological responses to exertional decompression stress. In this study, 15 healthy men, aged 20-50 yr, undertook 2 consecutive (same-day) ascents to 25,000 ft (7620 m) for 60 and 90 min, breathing 100% oxygen, each following 1 h of prior denitrogenation.

Decompression Sickness Risk in Parachutist Dispatchers Exposed Repeatedly to High Altitude.

Occurrences of severe decompression sickness (DCS) in military parachutist dispatchers at 25,000 ft (7620 m) prompted revision of exposure guidelines for high altitude parachuting. This study investigated residual risks to dispatchers and explored the potential for safely conducting repeat exposures in a single duty period. In this study, 15 healthy men, ages 20-50 yr, undertook 2 profiles of repeated hypobaric chamber decompression conducting activities representative of dispatcher duties.

Lung volumes, pulmonary ventilation, and hypoxia following rapid decompression to 60,000 ft (18,288 m).

Introduction: Rapid decompressions (RD) to 60,000 ft (18,288 m) were undertaken by six subjects to provide evidence of satisfactory performance of a contemporary, partial pressure assembly life support system for the purposes of flight clearance.

Methods: A total of 12 3-s RDs were conducted with subjects breathing 56% oxygen (balance nitrogen) at the base (simulated cabin) altitude of 22,500 ft (6858 m), switching to 100% oxygen under 72 mmHg (9.6 kPa) of positive pressure at the final (simulated aircraft) altitude.

Decompression sickness risk at 6553 m breathing two gas mixtures.

Introduction: The risk of severe decompression sickness (DCS) increases rapidly above 6248 m (20,500 ft) and is greater when breathing higher proportions of inert gas. Contemporary aircrew may be exposed to higher cabin altitudes while breathing molecular sieve oxygen concentrator (MSOC) product gas containing variable concentrations of oxygen, nitrogen, and argon. This study assessed the risk of DCS at 6553 m (21,500 ft) breathing two simulated MSOC product gas mixtures.