Survival Time of the Mouse as Related to Ambient pO2 Produced by Explosive Decompression

Abstract

Gelfan, X m s and Livingston ( 1 ) have shown that altitudes above 52,500 feet ( 7 7 mm Hg do not further reduce survival time of the rat; therefore the critcal poB of the ambient air for the rat would be 16 mm Hg. Rats decompressed in ovgen likewise showed no further effects of altitudes above 52,000 feet. However, rats survive more than twice as long when explosively decompressed in oxygen as in air but even then the critical decompression pressure remains the same for both air and oxygen. Luft, Clamann and Adler(2) state that mice survlive 25 seconds when rapidly decompressed to 43,000 feet in air or CO 52,000 feet in oxygen. They also list survival of mice for 80 seconds a t 32,000 fect in air. Hailman(3) using rats: and Stullken and Hiestand(4) using mice and chicks have determined the lowest oxygen pressures compatible with lifae. The former (3) found the critical p02 in rats decompressed in oxygen between 65 and 75 mm Hg, the latter(4) found the critical p02 in mice as 70.7 mm in baby chicks as 89.5 mm. Compared to decompression in oxygen, mice decompressed in air dted at an avepage pressure of 218.3 mm or a 4302 o;f 45.7 mm. Method.A decompression chamber consisting of a Pyrex flask was attached to: a large lballast chamber which in turn was evacuated by a vacuum pump. By opening a conlnection between the ballast chamber and the decompression chamber thie air in the latter was reduced in a fraction of a second to any desired pressure. Survival of the animal was measured with a stopwatch to the nearest R. 33.) Yale Aeromed. Unit Rep. KO. 56, 1947.