Effect of Experimental Saline Lavage on Pulmonary Mechanics and Morphology

The effect of unilateral pulmonary lavage with isotonic saline on alveolar morphology, pulmonary surfactant, and respiratory mechanics was studied in mongrel dogs. After pulmonary lavage, dilatation of alveolar capillaries, interstitial and intracellular edema, and alterations in the lamellated inclusions of granular pneumocytes were noted by light and electron microscopic examination of lung biopsies. The low surface activity in the lavaged lung indicated that the pulmonary surfactant could be efficiently removed by this technique. Quasistatic, pressure-volume determinations on the lavaged lung demonstrated a progressive deterioration of surface elasticity after the lavage procedure. Morphology, surface activity, and respiratory mechanics remained within normal limits in the control lung. Lavage with isotonic saline in large volumes appears to have a detrimental effect on pulmonary structure and function, with alterations in alveolar architecture, loss of pulmonary surface activity, and impairment of pulmonary mechanical function.