应用肺动态压力-容积曲线低位转折点选择最佳呼气末正压的研究

Dynamic pressure volume curve predicts the optimal positive end expiratory pressure in patients with acute respiratory distress syndrome

目的 探讨根据动态肺压力 容积曲线低位转折点压力 (Pinf)选择急性呼吸窘迫综合征 (ARDS)患者最佳呼气末正压 (PEEP)的可行性。方法 以 8例早期ARDS患者为研究对象 ,测定动态肺压力 容积曲线及Pinfd。采用低流速法测定准静态肺压力 容积曲线 ,并确定静态肺压力 容积曲线低位转折点压力 (Pinfs)。调整PEEP水平 ,观察患者血流动力学、肺机械力学和氧代谢的变化。结果 当PEEP从Pinfd - 6cmH2 O水平增加到Pinfd +6cmH2 O时 ,动脉血氧分压、动脉血氧饱和度、气道平均压和气道峰压均显著增加。与Pinfd +6cmH2 O比较 ,Pinfd - 4cmH2 O时的动态肺顺应性显著增高。Pinfd +6cmH2 O时的心脏指数有降低趋势 ,Pinfd - 4cmH2 O时的氧输送有升高趋势。当Pinfd为 (1 2 .8± 3 .2 )cmH2 O ,Pinfs为 (1 1 .0± 3 .2 )cmH2 O ,两者具有正相关性 (r =0 .99,P <0 .0 5)。回归方程为Pinfd =1 .66+1 .0 1×Pinfs。结论 当ARDS患者行机械通气治疗时 ,Pinfd - 4cmH2 O或Pinfs - 2cmH2 O为最佳PEEP ,可获得最大氧输送。

Objective To predict the best positive end expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS) patients with dynamic lung pressure volume (P V) curve. Methods Dynamic and static lung P V curves were determined in 8 patients with ARDS. The pressure of lower inflection point from dynamic lung P V curve (Pinfd) was compared with the pressure of lower inflection point from static lung P V curve (Pinfs). The effect of PEEP on hemodynamics, lung mechanics and gas exchange was observed. Results When PEEP increased from Pinfd-6 cm H 2O to Pinfd+6 cm H 2O, partial pressure of arterial oxygen, saturation of arterial oxygen, peak inspiratory pressure and mean airway pressure increased significantly ( P <0.05). Dynamic compliance was improved markedly with PEEP at Pinfd-4 cm H 2O when compared with PEEP at Pinfd+6 cm H 2O. Cardiac index reduced at Pinf+6 cm H 2O. Oxygen delivery was increased at Pinfd-4 cm H 2O. When Pinfs and Pinfd were (11.0± 3.2) cm H 2O and (12.8±3.2) cm H 2O, they were well correlated ( r = 0 99, P <0 05) and the regression equation was Pinfd=1.66+1.01×Pinfs. According to the regression equation, it was evident that Pinfd-4 cm H 2O equaled to Pinfs-2 cm H 2O. Conclusion When ARDS patients are treated with mechanical ventilation, Pinfd-4 cm H 2O and Pinfs-2 cm H 2O may yield the best PEEP and show maximal oxygen delivery.