An examination of the critical released gas volume concept in decompression sickness

Abstract

If P 1 is the pressure breathed by men for a prolonged period, and P 2 is the pressure to which it is just safe to decompress rapidly, then assuming the volume of tissue gas released upon decompression is critical, it is predictable from theoretical considerations that there is a relation between P 1 and P 2 of the form P 1 = a P 2 + b , where a and b are constants. The use of men as experimental subjects confirms this theoretical prediction for the case where mixtures of oxygen and helium are breathed. By assuming that the same critical volume of released gas provokes mild attacks of decompression sickness when air, or other respirable gases are breathed, the relevant values of a and b can be deduced, and the values accord well with the known facts for such gases. This analysis also offers an explanation for the changes in signs and symptoms of decompression sickness which can follow changes in the nature of the exposure to pressure.