DECOMPRESSION MORTALITY RELATED TO LUNG OEDEMA AND TENSION PNEUMOTHORAX.

Two groups of female hamsters (150 ± 50 g) were subjected to decompression from various pressures above atmospheric to a final pressure of 1 atmosphere. In one of these groups the wet:dry lung weight ratio was determined. Elevation of this ratio was taken as evidence of lung oedema. In the other group a postmortem test for valvular rupture of the lungs was applied. This test is based on the principle that air passing from a ruptured lung into the intrapleural space cannot reenter the lung, owing to valvular action of the lung tissue at the site of rupture. The results suggest that two modes of death may result from decompression: rapid death associated with tension pneumothorax, and relatively slow death associated with lung oedema. The relative incidence of tension pneumothorax, as compared to lung oedema, increases with increasing severity of decompression.