Role of Pulmonary Lymphatics in Chronic Pulmonary Edema

Previously small increases in canine pulmonary lymph flow found in acute pulmonary venous hypertension were ineffective in preventing fatal pulmonary edema. Our objective was to determine if functional expansion of the pulmonary lymphatic system could occur over a period of time and possibly aid in preventing critical pulmonary edema. Chronic heart failure was successfully induced in ten dogs by creating an aorticocaval anastomosis and administrating desoxycorticosterone trimethylacetate and a salt-rich diet. Pulmonary lymph flow was obtained at the time of sacrifice by tapping an isolated lymph-collecting chamber produced in the right external jugular vein. Gross increases in pulmonary lymph flow, varying from 300 to 2,800 per cent over the normal flow of 4 ml./hr., were found in 7 of the 10 dogs. These observations indicate that important functional expansion of the pulmonary lymph drainage can occur over a period of time, and such expansion may occur as a compensatory mechanism for the prevention of overt pulmonary edema.