Incidence of decompression-induced pulmonary haemorrhage in young and old rats

Seventeen young rats (40-52 days of age) and 17 old rats (545-702 days of age) were decompressed from one atmospheric pressure to an ambient pressure of 30 mmHg in 0.25 second. It was found that 11 of 34 young lungs (32%) and 23 of 34 old lungs (68%) showed decompression-induced pulmonary haemorrhage. The difference was statistically significant. The pulmonary haemorrhage of the old rats was markedly more severe than that of the young rats.