Total liquid ventilation (TLV) has been established as a ventilatory strategy for experimental respiratory distress that minimizes lung barotrauma and markedly improves physiologic outcome. The biochemical mechanisms that underlie these improvements are not understood. To evaluate the effect of age and ventilation strategy on pulmonary AOE activity, four groups of premature lambs [n = 27] (110 ± 3 days and 120 ± 2 days gestation) were supported for 4 hrs with either gas ventilation (GV) or TLV with LiquiVent® (FIO2 = 1.0). AOE activity of superoxide dismutase (tSOD), glutathione peroxidase (GPX), and catalase were normalized to tissue protein and compared to their age-matched fetal controls. Histological analysis was performed. (X ± SE; units/ mg protein).Table

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Despite differences in arterial oxygenation and barotrauma, there were no significant differences in AOE activity of SOD and GPX between GV and TLV lambs at either gestational age. Catalase activity in the older lambs was greater than that of younger lambs (** p < 0.05) and lower relative to their fetal controls (*p < 0.05). This finding suggests an age-specific response to oxygenation in premature lambs independent of ventilation strategy and that lung protection by TLV is afforded in a manner independent of antioxidant enzyme activity.

(Supp in part and consultation from Alliance Pharm.Corp., Hoechst Marion Roussel, Sharpe Foundation, Crown Foundation)