[Effect of acid aspiration on right lymph duct lymph flow and prostaglandin metabolites in dogs].

Aspiration of acid gastric contents into the airways is a major cause of pulmonary injury. The author investigated the effects of intratracheal instillation of hydrochloric acid in the anesthetized dogs on pulmonary hemodynamics, pulmonary lymph flow and protein content, and stable metabolites of prostaglandin F2 alpha (PGF2 alpha), prostacyclin (PGI2) and thromboxane A2 (TXA2). The author measured the concentrations of 15-keto-13, 14-H2-PGF2 alpha, 6-keto-PGF1 alpha and TXB2 in blood and pulmonary (right duct) lymph by specific radioimmunoassay. After intratracheal instillation of 0.1 N HCL, 3 ml.kg-1, the right duct lymph flow increased significantly from 1.3 to 4.5 ml.h-1, and pulmonary lymph-to-plasma protein ratio increased significantly from 0.63 to 0.70. There was no significant change in hemodynamics after acid instillation. There was no significant change in arterial or mixed-venous blood levels of any of the three metabolites. After acid instillation, the right duct lymph concentrations increased 2-fold for PGI2 metabolite, 3-fold for TXB2, and 7-fold for PGF2 alpha metabolite. The flow of metabolites (concentration x flow) increased 13-fold for 6-keto-PGF1 alpha, 14-fold for TXB2, and 40-fold for PGF1 alpha metabolite. The author concludes that intratracheal instillation of hydrochloric acid in anesthetized dogs: 1) increases pulmonary microvascular permeability, and 2) stimulates the pulmonary generation of PGF2 alpha, prostacyclin and thromboxane, and that 3) the analysis of pulmonary lymph flow and its constituents is a useful means for the study of lung injuries.