SURFACTANT REPLACEMENT INCREASES COMPLIANCE IN PREMATURE LAMB LUNGS DURING PARTIAL LIQUID VENTILATION IN-SITU

Treatments available to improve compliance in surfactant-deficient sta tes include exogenous surfactant (ES) and either partial (PLV) or tota l liquid ventilation (TLV) with perfluorochemical (PFC). Because of th e additional air-lung and air-PFC interfaces introduced during PLV com pared with TLV, we hypothesized that compliance would be worse during PLV than during TLV. Because surfactant is able to reduce interfacial tension between air and lung as well as between PFC and lung, we furth er hypothesized that compliance would improve with surfactant treatmen t before PLV. In excised preterm lamb lungs, we used Survanta for surf actant replacement and perflubron as the PFC. Compliance during PLV wa s intermediate between TLV and gas inflation, both with and without su rfactant. Surfactant improved compliance during PLV, compared with PLV alone. Because of the force-balance equation governing the behavior o f immiscible droplets on liquid surfaces, we predict that PFC droplets spread during PLV to cover the alveolar surface in surfactant-deficie nt lungs during most of lung inflation and deflation but that the PFC would retract into droplets in surfactant-sufficient lungs, except at end inspiration.