A hallmark of Acute Respiratory Distress Syndrome (ARDS) is a nonhomogeneous pattern of lung injury. Nonuniform distribution of exogenous surfactant may be the limiting factor precluding clinical response when administering surfactant by conventional methods. We recently demonstrated that surfactant administered by lavage, but not bolus, reversed the pulmonary function abnormalities and resulted in uniform surfactant distribution in an acute lung injury model induced by whole lung saline lavage (WLSL),(AJRCCM,1996;153:1838-43); even at a phospholipid dose 25% of the bolus. In this present study, a nonhomogeneous lung injury was induced by WLSL to achieve a Pa02 <80 torr in FI02=1.0, followed by meconium injected into the right lung. We compared the effects of Infasurf administered by lavage(n=3;LS), bolus (n=3;BS) and Control/no Rx (n=2; C). LS utilized a volume of 35 ml/kg (4 mg/ml) instilled and then drained, both by gravity. Both treatment groups retained the same volume (avg=4ml/kg) and dose (DPPC avg=19 mg/kg) of surfactant. Results: Statistically significant increases in Pa02 occurred in the LS group in contrast to BS and C. Values at 240 min post-treatment: LS 307±55 torr; BS 109±7 torr; C 46±7 torr, (P<0.05). Other improvements in pulmonary function favored LS, but were not significant. We conclude that lavage administration of surfactant is superior to bolus in this lung injury model. We speculate that: 1) the effective dose of surfactant in acute lung injury may be lower than previously considered; 2) the benefit of LS is related to a combination of more uniform surfactant distribution, as well as removal of meconium and foreign protein from the lung.
Supported by NIH RCMI P20 RR/AI 11091; Leahi Fund of Hawaii Community Foundation; and Dept. Clin. Invest., TAMC.
