持续气管内吹气在急性肺损伤幼猪通气中的作用

目的 观察持续气管内吹气联合保护性低通气压控制通气对内毒素诱导急性肺损伤幼猪的疗效.方法 12只上海小白猪,内毒素60 μg,/ks静脉维持诱导肺损伤.随机(随机数字法)分为单纯机械通气组(MV,n=6)和联合气管内吹气组(TGI,n=6).呼吸机设置参数为吸气峰压10cmH2O(1 cmH2O=0.981 kPa);呼吸末正压2 cmH2O;呼吸频率30次/min,吸气时间0.4 s;流速20 L/min.TGI组经留置婴儿胃管给予2 L/min空气吹入,调节呼吸机吸氧浓度使吸入混合气体所测氧浓度为0.4.记录牛命体征、中心静脉压、通气功能和呼吸力学参数及动脉血气分析.结果 急性肺损伤成模后4 h,与MV组比较,TGI组呼气潮气量、通气效率指数显著升高(P<0.01),平均气道阻压下降(P<0.05).动脉血气分析提示TGI组pH值明显纠正,二氧化碳分压显著下降(P<0.01);同时氧分压、氧合指数显著改善(P<0.05).但两组心率、呼吸频率、动脉压、中心静脉压、肺顺应性和平均气道阻力差异均无统计学意义.组织学检查提示TGI组肺组织炎症程度及出血状况明显减轻.结论 持续气管内吹气可以显著提高急性肺损伤机械通气效率,促进二氧化碳排出,并改善氧合能力,在急性肺损伤治疗中具有一定的应用前景.

Continuous intra-tracheal gas insufflation during mechanical ventilation in juvenile piglets with acute lung injury induced by endotoxin

Objective To evaluate the effects of continuous intra-tracheal gas insufflation (TGI) during mechanical ventilation for protecting the juvenile piglets with acute lung injury (ALI) induced by endotoxin. Method Twelve healthy juvenile piglets were anesthetized and mechanically ventilated at 2 cmH2O PEEP with 10 cmH2O peak inspiration pressure. The piglets were challenged with lipopolysaccharide (LPS) and randomly (random number) assigned to two groups (n = 6 each): (1) piglets treated with mechanical ventilation alone (group MV) and (2) piglets treated with TGI by continuous airway flow of 2 L/min (group TGI). FiO2 was set at 0.4 to avoid oxygen toxicity, and the piglets were continuously monitored with an oxygen analyzer. Results Tidal volume, ventilation efficacy index and mean airway pressure were significantly improved in piglets of TGI group (P < 0.01 or P < 0.05). Four hours after ALI, pH decreased to below 7.20 in piglets of MV group, and was higher in piglets of TGI group (P < 0.01). Similarly, PaCO2 was stable and was significantly lower in piglets of TGI group than that in piglets of MV group (P < 0.01). PaO2 and PaO2/FiO2 increased in piglets of TGI group (P < 0.05). There were no significant differences in heart rate, respiraaatory rate, mean arterial pressure, central venous pressure, dynamic lung compliance and mean resistance of airway between two groups. Lung histopathological changes showed severe inflammation,and intra-alveolar hemorrhage and interstitial patchy hemorrhage were ameliorated and the lungs were more homogenously expanded in piglets of TGI group. Conclusions Continuous TGI during MV can significantly improve gas exchange and ventilation efficacy, and may provide a better treatment for acute lung injury.