High surface tension pulmonary edema

Abstract

Dogs were anesthetized with pentobarbital and placed on a piston ventilator with room air. Ten animals received an endobronchial lavage of normal saline (3 mg/kg). Ten other animals received an endobronchial lavage of the same volume of a nonionic detergent, Tween 20, 5% in saline. Detergent lavage was shown by Wilhelmy balance to increase surface tension of lung extracts. Saline lavage did not alter the surface tension of lung extracts. No significant differences between the groups were noted in cardiac output, left ventricular end diastolic pressure, mean pulmonary artery pressure, or colloid oncotic pressure. Static compliance and arterial PO 2 were decreased following detergent lavage. Animals were sacrificed 2 hr after lavage and pulmonary extravascular water volume (PEWV) was measured gravimetrically. Saline-lavaged lungs with normal surface tension had a PEWV of 4.3 ml/g dry lung. Tween-lavaged lungs with increased surface tension had a PEWV of 5.3 ml/g dry lung ( P < 0.005). When the estimated volume of residual lavage solution remaining in the lung parenchyma was subtracted from the total wet lung wt, the corrected PEWV was 3.62 ± 0.12 ml/g dry lung for saline-lavaged lung and 4.76 ± 0.19 ml/g dry lung for Tween-lavaged lung. PEWV for 11 control animals ventilated 2 hr without lavage was 3.61 ± 0.13 ml/g dry lung. It is concluded that, experimentally, high alveolar surface tension can induce pulmonary edema even when pulmonary microvascular hydrostatic and colloid oncotic pressures are normal.