肺复张策略对急性呼吸窘迫综合征模型犬压力-容积曲线和肺组织病理的影响

 目的：探讨肺复张策略（LRM）对急性呼吸窘迫综合征（ARDS）模型犬静态P-V曲线和肺组织病理的影响。方法：健康犬24只，随机分为肺外源性ARDS（ARDSexp）组和肺内源性ARDS（ARDSp）组，每组12只，经股静脉注射油酸复制ARDSexp模型，盐酸灌肺复制ARDSp模型，再随机各分为2组，每组6只，分别采用肺保护通气策略（LPVS）和LPVS联合以压力-容积曲线为导向的LRM（LPVS+LRM）进行机械通气。LRM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。观察LRM后P-V曲线LIP、UIP以及肺复张容积变化。4 h后取肺组织行病理学评分。结果：应用LRM后，ARDSp组和ARDSexp组LIP均明显降低，与ARDSp组相比，ARDSexp组LIP下降更为显著；ARDSexp组4例犬P-V曲线出现UIP消失，2例无改变，ARDSp组犬UIP无明显变化；肺复张容积增加，肺病理损伤评分明显下降，ARDSp组的改善程度不如ARDSexp组。结论：LRM可降低LIP，导致P-V曲线发生改变，LRM后应重新根据P-V曲线调整呼吸机通气参数；对于不同原因ARDS，LRM具有增加肺复张容积、减轻肺损伤的作用，ARDSexp组的治疗效果明显优于ARDSp组。

Effects of lung recruitment maneuver on pressure-volume curve and lung histopathology in a canine model of ARDS

AIM: To investigate the effect of lung recruitment maneuver (LRM) on pressure-volume curve and lung histopathology in a canine model of acute respiratory distree syndrome (ARDS). METHODS: Twenty-four healthy dogs were randomly divided into extrapulmonary ARDS (ARDSexp) group and pulmonary ARDS(ARDSp) group. The dogs in ARDSexp group were injected with oleic acid through femoral vein and the dogs in ARDSp group inspired hydrochloric acid to induce lung injury. The dogs in both ARDSexp group and ARDSp group were randomly sub-divided into lung protective ventilation strategy (LPVS) group and LPVS+LRM group. Pressure-controlled ventilation (PCV) was employed to LRM.The upper limit of the pressure was set as upper inflection point (UIP), and the positive end-expiratory pressure (PEEP) was set as low inflection point (LIP)＋2 cmH₂O. The duration of LRM was set to be 60 s. LIP, UIP and lung recruited volume were measured before and after LRM. All the dogs were killed after 4 h of ventilation. The histopathological changes and Smith scores of the lungs were measured. RESULTS: After LRM, LIP value was significantly decreased in ARDSp group, and was decreased more significantly in ARDSexp group. The UIP was disappeared after LRM in 4 dogs of ARDSexp group, but the UIP in the dogs of ARDSp group did not change significantly after LRM. Compared with ARDSp group, the lung recruited volume significantly improved, and the lung injury score also significantly decreased after LRM in ARDSexp group. The treatment results were better in ARDSexp group than those in ARDSp group. CONCLUSION: LRM decreases the level of LIP and modifies the P-V curve significantly. We should adjust the parameters of ventilator according to the P-V curve after LRM. LRM improves lung recruited volume and prevents lung injury in ARDSexp and ARDSp, and better treatment effects are obtained in ARDSexp dogs than ARDSp dogs.