Hyperoxia increases ventilator-induced lung injury and protective effects of dexamethasone

Objective To study the effects of hyperoxia on ventilator-induced lung injury(VILI) and the protection of dexamethasone.Methods Thirty-six male Sprague-Dawley rats were randomly divided into three groups: group A received large tidal volume ventilation with room air(RA),group B received large tidal volume ventilation with 100%O2,group C was pretreated with dexamethasone.Arterial blood gases were measured every one hour,then oxygenation index(PaO2/FiO2) was calculated.wet-to-dry weight ratio(W/D) of left lung was determined.WBCs,neutrophils,TNF-α,IL-1β and MIP-2 levels in BALF,malondialdehyde(MDA) and superoxide dismutase(SOD) levels in the lung were assayed respectively.Results Oxygenation index decreased significantly in group B than A(P0.01).The wet-to-dry weight ratio of left lung,WBCs,neutrophils,TNF-α,IL-1β,and MIP-2 levels in BALF,MDA levels in the lung increased significantly in group B than A(P0.01),but the levels of SOD significantly decreased in group B than A(P0.01).Oxygenation index increased significantly in group C than B.The wet-to-dry weight ratio of left lung,WBCs,neutrophils,TNF-α,IL-1β,and MIP-2 levels in BALF,MDA levels in the lung were significantly lower in group C than group B(P0.01),but the levels of SOD significantly increased in group C than B(P0.01).Conclusion Hyperoxia can increase ventilator-induced lung injury,and dexamethasone has obvious protective effects.