Cardiopulmonary changes following 24-36 hours of hyperoxia.

Cardiopulmonary variables were studied in rabbits breathing room air following 24-36 h of 100 percent 0-2 exposure. Initially, arterial pH and P-co-2 remained within normal limits while arterial P-0-2 decreased significantly. Cardiac output and oxygen consumption increased significantly. Static lung compliance was decreased, and histologic examination showed pulmonary hemorrhage, atelectasis, and adema. Myocardial function under these conditions was restored, and the myocardium was able to produce a compensatory increase in cardiac output. Therefore, changes in myocardial function, as related to oxygen toxicity, are reversable phenomena.