AIM: To determine the effects of recruitment maneuver( RM ) strategy on oxygen metabolism and hemodynamics in canine models of extrapulmonary acut respiratory distress syndrome( ARDSexp ) and pulmonary acute respiratory distress syndrome( ARDSp ).METHODS: Twelve healthy canines were randomly divided into ARDSexp group and ARDSp group with 6 dogs each.To induce lung injury, the ARDSexp dogs were injected with oleic acid through femoral vein, and hydrochloric acid were administered by lung lavage to the ARDSp dogs.Pressure control ventilation ( PCV )with lung protective ventilation strategy ( LPVS ) was employed to RM.Phigh was set to upper inflection point ( UIP ), and Plow was set to lower inflection point ( LIP ) + 2 cmH2O.The duration of RM was 60 s and followed by baseline ventilatory settings.The indexes of oxygen metabolism and hemodynamics were measured before and after RM.RESULTS: After RM, arterial partial pressure of oxygen ( PaO2 ), venous partial pressure of oxygen ( PvO2 ), mixed venous oxygen saturation ( SvO2 ) and oxygen delivery ( DO2 ) obviously increased, and oxygen extraction ratio ( ERO2 ) gradually decreased in both groups.PaO2, PvO2, SvO2 and DO2 in ARDSexp group were significantly higher than those in ARDSp group, and ERO2 in ARDSexp group were significantly lower than that in ARDSp group.Although mean pulmonary arterial pressure ( MPAP ), central venous pressure ( CVP ) and pulmonary artery wedge pressure ( PAWP ) significantly increased and mean arterial pressure ( MAP ) and cardiac index ( CI ) obviously decreased in both groups during RM, they reversed rapidly after RM.During RM, MPAP, CVP and PAWP were significantly higher, and MAP and CI were significantly lower in ARDSp group than those in ARDSexp group.CONCLUSION: RM increases oxygen delivery and improves tissue anoxia, and the better effects are obtained in ARDSexp dogs than those in ARDSp dogs.The effects of RM on hemodynamics are temporary and the ill effects are worse in ARDSp dogs than those in ARDSexp dogs.%目的:探讨肺复张对肺内、外源性急性呼吸窘迫综合征(ARDS)模型犬氧代谢和血流动力学的影响.方法:健康杂种犬12只,随机分为肺外源性ARDS(ARDSexp)组和肺内源性ARDS(ARDSp)组,每组6只.股静脉注射油酸复制ARDSexp模型,盐酸灌肺复制ARDSp模型.制模成功后,行机械通气,采用肺保护通气策略(LPVS)并给予1次肺复张(RM).RM采用压力控制通气(PCV),压力上限为高位转折点(UIP),呼气末正压(PEEP)为低位转折点(LIP)+2 cmH2O,维持时间60 s,RM后继续原方案通气.观察不同阶段氧代谢指标和血流动力学的变化.结果:RM后两组动脉血氧分压(PaO2)、静脉血氧分压(PvO2) 、混合静脉血氧饱和度(SvO2)和氧输送量(DO2)明显升高,氧摄取率(ERO2) 逐渐降低;ARDSexp组的PaO2、PvO2、SvO2和DO2高于ARDSp组,ERO2则低于ARDSp组.RM时两组平均肺动脉压(MPAP)、中心静脉压(CVP)、肺动脉嵌压(PAWP)均显著增加,ARDSp组与ARDSexp组相比较无显著性差异,但RM结束后两组均逐渐恢复至基础水平.RM时两组平均动脉压(MAP)和心脏指数(CI)下降,但很快恢复至基础水平,ARDSp组下降幅度更为显著.结论:RM可以提高氧输送和改善组织缺氧,ARDSexp组的效果优于ARDSp组;RM对血液动力学会造成短暂的影响,ARDSp组受到的影响大于ARDSexp组.
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