title: Investigation of arterial bloodgases at altitude using constant-flow oxygen masks.
abstract: Arterial blood oxygen tensions up to 6700 m altitude (FL220) were measured polarographically while subjects breathed from various masks with constant-flow oxygen. The Sierra and Aro masks used for emergency decompression descent in commercial passenger aircraft, gave mean PaO2's of 130 +/- 7.6 and 130 +/- 12.1 torr at 6700 m (FL220) and 90 +/- 3.8 and 77 +/- 3.35 torr at 4260 m (FL140), respectively, when supplied with oxygen flows corresponding to those available in the Boeing 747. These oxygen tensions during descent are acceptable for normal physiological function in a heterogeneous population of air travellers whereas breathing ambient air during return to base at 4260 m (FL 140) (PaO2 of 48 or less) is not acceptable. The valveless Hudson 1007 and Puritan 114011 masks, used for air ambulance service, gave mean PaO2's of 110 +/- 2.7 and 98 +/- 4.5 torr at 6700 m and 80 +/- 3.0 and 77 +/- 2.5 torr at 4260 m under the same condition--significantly less than the Sierra mask.
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D008297:Male; D008397:Masks; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen