Oxyhemoglobin saturation following rapid decompression to 18,288 m preceded by diluted oxygen breathing.
This investigation studied oxyhemoglobin saturation (SaO2) and cardiovascular indices after rapid decompression (RD). Before RD, fractional inspired O2 concentration (FIO2) simulated the range of product gas from molecular sieve O2 generating systems (MSOGS). Four subjects breathed 1.0-0.80 FIO2 at 6,858 m. After decompression to 18,288 m, the subject received 1.0 FIO2 at a positive pressure of 70 mm Hg for 3 min. There were no incidents of severe hypoxia. The mean SaO2 was 98.0% before RD. After RD, SaO2 was maintained at the pre-RD level for 8 s, decreased rapidly over the next 10 s, and over the rest of the 1st min decreased more gradually to reach approximately 82%. Varying FIO2 before RD had no effect on the alteration in SaO2, heart rate, stroke index, and blood pressure after RD. The MSOGS O2 product range offers adequate protection against hypoxia during RD to 18,288 m.
Buick
F
F
Defence and Civil Institute of Environmental Medicine, Downsview, Ontario, Canada.
Porlier
J A
JA
D000328:Adult; D000531:Altitude; D001794:Blood Pressure; D003664:Decompression; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000209:etiology; D008297:Male; D010100:Oxygen / Q000008:administration & dosage*; D010108:Oxyhemoglobins / Q000032:analysis*; D012119:Respiration; D013026:Space Flight; D013318:Stroke Volume
D010108:Oxyhemoglobins; D010100:Oxygen