Effects of atelectasis on pulmonary surfactant and quasi-static lung mechanics.

Effects of . mechanics. J. Appl. Physiol. 20(5) : 859-864. Ig65.-The effects of unilateral atelectasis on pulmonary surfactant activity and lung mechanics have been studied in rabbits. Total left lung collapse was produced by pneumothorax and maintained from go min to 8 days. Quasi-static pressure-volume relationships were determined with air and saline after varying intervals. Surface activity of minced lung extracts and of dried foam obtained by tracheal washings was measured on a surface balance. A marked decrease in lung inflatability progressing with duration of collapse was noted during air and saline pressure-volume studies. However, deflation characteristics of all atelectatic lungs were normal. Extracts from minced, in vitro reinflated atelectatic lung showed a variable but significant loss of surface activity compared to the right (normal) lung of the same animal. However, highly surface-active material could be demonstrated in the collapsed lungs by the more efficient extraction procedure of tracheal foaming. Correlation exists therefore between normal volume stability of alveoli after initial inflation and presence of surfactant activity in atelectatic lungs.