UNILATERAL PULMONARY-EDEMA IN RABBITS AFTER RE-EXPANSION OF COLLAPSED LUNG

The effects of the mode of reinflation and the duration of prior collapse on the development of unilateral pulmonary edema following reexpansion of collapsed lung were studied in a rabbit model simulating the human syndrome of 'reexpansion pulmonary edema'. The right lungs of rabbits were maintained in an atelectatic state for 0.5 hr to 8 days, by injection of air into the pleural space. Reexpansion was achieved in 2 hr by application of positive pressure to the airway while a chest tube was connected to underwater seal, or by application of negative pressure (-20 to -100 Torr) to a screened window in the parietal pleura. The lung surface pressures the authors actually applied by the two methhods are not known. Animals where then killed and pulmonary edema was determined by wet-to-dry weight ratios. The incidence of unilateral pulmonary edema increased as the duration of prior collapse was increased (85% after 7-8 days; 17% after 3 days; and 0% after 0.5 hr) when reinflated with -100 Torr applied to the pleural window. Although the incidence was less, it also occurred following the use of pleural window pressures less negative than -100 Torr, and after reinflation by positive airway pressure.