THE EFFECT OF SHOCK AND FAT EMBOLUS ON PULMONARY MECHANICS AND GAS EXCHANGE

Abstract

Four groups of dogs were studied; a control group, a group which had an i.v. injection of 0.035 milliliter/kg of oleic acid; a group subjected to moderate shock for one hr; and a group that was subjected to a combination of moderate shock and i.v. injection of 0.035 milliliter/kg of oleic acid. Prior to injury and every 30 min for 2 hr, followed by every one hr for 4 hr, lung mechanics, respiratory work, shunt fraction, and cardiac output were determined. These studies were repeated on days 1 and 2 after injury. The arterial pO2 values were not significantly different in the control and experimental groups on any studies during the experimental day. On day 3, arterial pO2 values were significantly depressed in both the oleic and the shock plus oleic acid groups. The shunt fraction was significantly elevated only on the final determination in the oleic acid and shock group. Compliance fell and respiratory work increased in all experimental groups but were unchanged in the control group. The dogs that suffered the combined insults of oleic acid injection and shock showed a more profound fall in compliance than did those in the other experimental groups. These findings point to the greater sensitivity of measurements of respiratory mechanics than blood gas studies in indicating early changes in lung function. They also suggest that shock aggravates the injury to the lungs when produced by injection of fatty acids.