Effect of lung water content, manipulated by intratracheal furosemide, surfactant, or a mixture of both, on compliance and viscoelastic tissue forcesin lung-lavaged newborn piglets

Objective:To study the impact of lung water content and its reduction by a topically applied diuretic on respiratory and lung tissue mechanics in comp arison with surfactant administration in surfactant-deficient newborn pigle ts with lavage-induced lung injury, Design: Controlled, randomized study. Setting: Animal research facility. Subjects: Newborn piglets. Treatment Piglets were surfactant depleted by lu ng lavage and, after a pretreatment period, randomly treated with intratrac heal furosemide, furosemide and surfactant, or with surfactant alone. Measurements and Main Results:Dynamic compliance (C-DYN), static compliance (Csr), stress-adaptation pressures (P-DIFF) and post mortem lung water con tent were determined. Static compliance in the furo-semidesurfactant group was not significantly higher than in the surfactant group. At the end of th e study, CST did not differ between the three groups because Csr in the fur osemide group had increased to values similar to those of the surfactant-co ntaining treatment groups: Csr F+S 0.73 +/- 0.2 mL/cm H2O/kg body weight (B W); CST: 0.61 +/- 0.11 compliance was inversely and P-DIFF was directly cor related to lung water (LW) content (CST VS. LW: r(2) = .59, p = .001; CDYN vs. LW: r2 = .49, p = .006; PDIFF vs. LW: r2 = .37, p = .069), independent of the type of treatment Changes in Csr and C-DYN were inversely related to changes in P-DIFF. Intrapulmonary furosemide was more rapidly absorbed whe n administered to the surfactant-depleted lung alone compared with the mixt ure with surfactant, and intrapulmonary furosemide had a rapid systemic eff ect Conclusion: Although the combination of surfactant with a diuretic failed t o increase respiratory compliance to a significantly larger extent than sur factant atone, furosemide at the end of the study increased respiratory com pliance to a level similar to surfactant-containing treatments. Lung water content and, to a lesser extent, the absence or presence of surfactant appe ared to determine lung mechanics, and its impact on lung mechanics was simi lar to surfactant administration.