Incidence of Decompression Sickness in Mice as a Function of the Relative Concentrations of Helium and Nitrogen in the Inspired Gas Mixture

摘要

Two hundred fifty mice were exposed to a pressure equivalent to 400 feet of seawater for 30 minutes while breathing a mixture of 2.09 - 2.33% oxygen and either (1) 97.8% N2, (2) 73.0% N2 24.6% He, (3) 48.7% N2 49.1% He, (4) 23.7% N2 74.2% He, or (5) 97.8% He. In each case, decompression to sea level followed an exponential course and was 90% complete in approximately 8 sec. The incidence of decompression sickness, as manifested by hind limb paralysis, convulsions and death, was found to vary with the relative proportions of helium and nitrogen in the inspired gas mixture. The greatest incidence was observed with the mixture containing nitrogen alone; the least with the mixture having equal proportions of nitrogen and helium in the inert gas fraction. Statistically, the bends incidence with all four mixtures containing helium was significantly lower (P