Respiratory gas exchange during positive pressure breathing and rapid decompression to simulated altitudes of 18.3 and 24.4 km.
Respiratory gas exchange was studied, using the technique of mass spectrometry, during events of slow and rapid decompression of human subjects to simulated altitudes of 60,000 and 80,000 ft (18.3 and 24.4 km, respectively). Positive breathing pressures and G-suit counterpressures were employed in three series of decompression experiment. Low levels of inspired carbon dioxide and nitrogen reflected the rebreathing of gases throughout the experiments. Application of a positive breathing pressure of 70 torr, accompanied by a jerkin pressure equal to breathing pressure and a G-suit counterpressure of four times the breathing pressure on the trunk and limbs, respectively, maintained alveolar oxygen at physiologically safe levels during decompression to 60,000 ft (18.3 km) altitude. Similarly, 80 torr positive breathing pressure, in combination with four times the breathing pressure in the G suit, adequately satisfied the requirements for oxygen during rapid decompression to 80,000 ft (24.4 km) simulated altitude.
D000337:Aerospace Medicine; D000531:Altitude; D002245:Carbon Dioxide; D003664:Decompression; D005676:Gravity Suits; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000502:physiology; D010100:Oxygen; D011175:Positive-Pressure Respiration; D012123:Pulmonary Ventilation; D012119:Respiration
D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen