Large Tidal Volume Mechanical Ventilation Aggravates Acute Lung Injury and Protective Effects of Glutamine

Objective To study the effects of two different tidal volume mechanical ventilation on lipopolysaccharide(LPS)-induced acute lung injury(ALI),and explore the effects of glutamine on ALI.Methods Thirty male Sprague-Dawley rats were randomly divided into three groups.After anesthesia and tracheotomy were performed,the rats were challenged with intratracheal LPS(5mg/kg)and received ventilation for 4 hours with small animal ventilator.Group A received conventional tidal volume,while group B received large tidal volume.Group C received large tidal volume as well,with glutamine injected intravenously 1 hour before ventilation.Arterial blood gases were measured every one hour.4 hours later,the rats were killed by carotid artery bleeding.The total lung wet weight was measured and lung coefficient(total lung wet weight/body weight×100)was counted.WBCs and neutrophils in BALF were counted.Protein concentration,TNF-α,IL-6,and cytokine-induced neutrophil chemoattractant-1(CINC-1)levels in BALF,myeloperoxidase(MPO),and superoxide dismutase(SOD)levels in the lung were assayed respectively.Results PaO2 and SOD levels decreased more significantly in group B than those of group A.The lung coefficient,WBCs,neutrophils,protein,TNF-α,IL-6,and CINC-1 levels in BALF,MPO levels in lung increased more significantly in group B than those of group A.PaO2 and SOD levels were significantly higher in group C than those of group B.The lung coefficient,WBCs,neutrophils,protein,TNF-α,IL-6,and CINC-1 levels in BALF,MPO levels in lung were significantly lower in group C than those of group B.Conclusion Large tidal volume mechanical ventilation aggravates LPS-induced ALI,and glutamine has obviously protective effects.