The effects of indomethacin on edema and gas exchange in canine acid aspiration.

Previous studies have suggested that prostaglandin synthesis inhibition might alter lung water accumulation in low pressure pulmonary edema. Therefore we studied the effects of indomethacin administration on edema formation, hemodynamics, and gas exchange in canine acid aspiration. Fourteen pentobarbital anesthetized dogs received 1 ml/kg of 0.1 N HCl intratracheally and then 7 received indomethacin (5 mg/kg) and 7 served as time controls. Lung liquid was measured in vivo by a double indicator technique and at the end of the experiment by gravimetric determinations. Following HCl administration, venous admixture (Qva/Qt) increased in both groups. Over the succeeding 4 h Qva/Qt decreased after indomethacin administration by 4.1 +/- 14.2%, but increased in the control group by 10.9 +/- 11.5% (P less than 0.05). Cardiac index remained constant in the control group but decreased after indomethacin from 232 +/- 89 ml X kg-1 X min-1 to 167 +/- 75 ml X kg-1 X min-1. Lung liquid accumulation, however, was similar between both groups. We believe that the changes in Qva/Qt associated with indomethacin can be explained by the known observations that decreases in cardiac output are associated with decreases in intrapulmonary shunt.