THE EFFECT OF ACUTE PULMONARY EDEMA UPON LUNG COMPLIANCE

Abstract

Thirty-eight puppies were paired according to weight and one of each pair was infused intravenously with normal saline and levarterenol in order to produce acute pulmonary edema. The lungs were immediately excised and the relationship of gas volume to airway pressure was examined in either the natural or gas-free postmortem state. The edematous lungs consistently opened at lower pressures than did the nonedematous lungs. After opening had occurred, the rise in airway pressure for a given increase in gas volume was often, but not invariably, greater in the edematous lung. The effect of change in pulmonary vascular volume was studied in eight excised adult dog lungs. In the absence of pulmonary edema, an increase in vascular volume [SEE FIG. 5. IN SOURCE PDF] caused a slight increase in airway pressure. In the same lungs, massive pulmonary edema increased airway pressure independent of vascular pressure. [SEE FIG 4 IN SOURCE PDF] These findings suggest that changes in the bronchial mucus-alveolar lining layer complex, parenchyma, and vascular volume all contribute to the changes in compliance seen in acute pulmonary edema. The change in the bronchial mucus-alveolar lining layer complex is of such a nature as to increase compliance, whereas the changes in the parenchyma and pulmonary blood volume decrease compliance.