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 hemodynamic variables. Methods: A balloon-tipped catheter was fluoroscopically passed from a jugular vein into the right lower lobe (RLL) pulmonary artery of rats, its distal lumen used to measure pulmonary artery pressure. Inflation allowed measurement of RLL wedge pressure, which represents pulmonary venous pressure. After inflation, the RLL underwent constant 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 the experiment, RLL changes in pulmonary artery pressure reflect changes in pulmonary vascular resistance. Results: Animals given preburn lymph had no alterations in RLL pulmonary hemodynamics. The immediate, significant (p < 0.005, analysis of variance) increases in RLL pulmonary artery pressure (16.2 ± 2.3 mm Hg at baseline vs. 35.4 ± 2.1 mm Hg at 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 hypertensive response to postburn lymph warrants further investigation.