Systemic and Coronary Pressure-Flow Relationships During Total Body Perfusion in the Dog

Abstract

Fifty dogs have been perfused at flow rates of between 5 and 100 cc/kg/min. with complete cardio-pulmonary bypass for up to three hours using a pump-oxygenator. There was an approximately linear relationship between pressure and flow. Extrapolation to zero flow produced an intercept on the pressure axis of approximately 20 mm Hg. Calculated total systemic resistance was more uniformly related to flow than to pressure. Coronary blood flow did not correlate with perfusion pressure. There was, however, an inverse relationship between perfusion rate and the percentage of total flow passing through the coronary bed. Coronary resistance decreased with perfusion time whereas total systemic resistance rose initially and then declined. Total peripheral resistance in these open chest perfused animals was one to two times the accepted normal for the intact dog. The actual value varied with the anesthetic agent used.