Surfactant phosphatidylcholine in thermally injured pigs

Objective: To investigate the effect of a thermal injury an pulmonary surfactant phosphatidylcholine kinetics, Design: Random, controlled study, Setting: University research laboratory. Subjects: Yorkshire swine (n = 8) with and without a 40% total body surface area burn. Interventions: A new isotope tracer methodology was used to quantify surfactant phosphatidylcholine kinetics. Four days after burn, [1,2-C-13(2)]acetate and [U-C-13(16)]palmitate were infused continuously for 8 hrs to quantify surfactant phosphatidylcholine synthesis, secretion, recycling, and irreversible loss. Measurements and Main Results:The total surfactant phosphatidylcholine pool size was reduced from the control value of 2.65 +/- 0.05 to 1.61 +/- 0.08 mu mol/g wet lung in burned animals (p < .05), as was the proportional contribution of palmitate to lung surfactant phosphatidylcholine composition. This reduction was associated with a significant decrease in lung dynamic compliance from the control Value of 66 +/- 6 to 55 +/- 6 mL/cm H2O for burned pigs (p < .05). The most prominent response of lung phosphatidylcholine kinetics was a decrease in the total lung phosphatidylcholine synthesis from a central value of 12.7 +/- 1.2 to 5.5 +/- 0.3 nmol phosphatidylcholine-bound palmitate.hr(-1).g of wet lung(-1) in burned animals (p < .05). Conclusions: Pulmonary phosphatidylcholine content and palmitate composition decrease after burn injury because of a decrease in the rate of phosphatidylcholine synthesis. These responses likely contribute to impaired lung compliance.