A NOVEL MODEL TO STUDY THE EFFECTS OF BURN LYMPH ON PULMONARY VASCULAR HEMODYNAMIC VARIABLES

Objective: To determine the effects of burn lymph on pulmonary hemodyn amic variables. Methods: A balloon-tipped catheter was fluoroscopicall y passed from a jugular vein into the right lower lobe (RLL) pulmonary artery of rats, its distal lumen used to measure pulmonary artery pre ssure, Inflation allowed measurement of RLL wedge pressure, which repr esents pulmonary venous pressure. After inflation, the RLL underwent c onstant flow pump-perfusion with carotid artery blood. Preburn (n = 5) or postburn (n = 6) dog lymph was infused into the RLL for 50 minutes . Measurements: Because perfusion flow rate was constant throughout th e experiment, RLL changes in pulmonary artery pressure reflect changes in pulmonary vascular resistance. Results: Animals given preburn lymp h had no alterations in RLL pulmonary hemodynamics. The immediate, sig nificant (p < 0.005, analysis of variance) increases in RLL pulmonary artery pressure (16.2 a 2.3 mm Hg at baseline vs. 35.4 +/- 2.1 mm Hg a t 30 minutes) and pulmonary vascular resistance (0.0 at baseline vs 1. 37 +/- 0.24 at 30 minutes) after burn lymph injection persisted beyond infusion interruption. Conclusion: The persistent pulmonary hypertens ive response to postburn lymph warrants further investigation.