Effects of tidal volume with different amount of gas after recruitment maneuver ventilation on lung vascular endothelial diastole function in rats with acute lung injury

Abstract

Objective To observe the effects of recruitment maneuver (RM) and tidal volume with different amount of gas after RM ventilation on lung diastole function in rats with acute lung injury (ALI). Method ALI rat models were induced by intravenous infusion of lipopolysaccharide (LPS) in dose of 6 mg/kg. Twenty-five rats were randomly(random number) divided into control group ( n = 5), ALI group ( n = 5), low tidal volume group (LV group,VT= 6 mL/kg, n = 5), sustained inflation (SI) with low tidal volume (SI+ LV group, VT=6 mL/kg, n = 5), and SI with moderate tidal volume group (SI+ MV group, VT= 12 mL/kg, n = 5). The RM carried out by using SI with airway pressure 30 cmH-2O for 30 seconds, and the positive end-expiratory pressure (PEEP)was set at 5 cmH2O. Lung tissue was taken after mechanical ventilation for 5 hours. The mean arterial pressure (MAP) was monitored throughout the entire course of experiment. Endothelin-1 ( ET-1 ), endothelial nitricoxide synthase (eNOS), and acetylcholine-(Ach-) induced endothelium-dependent relaxation response of isolated pulmonary artery rings were investigated after mechanical ventilation for 5 hours. Results The LPS increased the ET-1 level in lung tissue, decreased the level of eNOS in lung tissue, and impaired the Ach-induced endothelium-dependent relaxation response in pulmonary vassals, without obvious influence on systemic hemodynamics. SI + LV significantly reduced LPS-induced elevation of ET-1 level, and increased the level of eNOS, and significantly lessened endothelial dysfunction and ameliorated dysfunction od endothelium-dependent relaxation in pulmonary vas sals. Conclusions RM with high tidal volume or lowtidal volume ventilation could improve the lung vascular endothelial function of rats with acute lung injury, and RM with low tidal volume ventilation could lessen more the injury of lung vascular endothelial diastole function in rats with acute lung injury. Key words: Acute lung injury; Recruitment maneuver; Low tidal volume; Lung vascular endothelium; Pulmonary artery diastole