低流速法选择急性呼吸窘迫综合征最佳呼气末正压的临床研究

Low flow technique predicts the optimal positive end-expiratory pressure in acute respiratory distress syndrome

目的 :用低流速法测定准静态肺顺应性曲线 ,探讨以曲线低位转折点压力 (Pinf)选择急性呼吸窘迫综合征 (ARDS)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 ,用低流速法测定准静态肺顺应性曲线 ,确定Pinf。分别以Pinf、Pinf -4、Pinf -2、Pinf+ 2、Pinf+ 4和Pinf + 6作为PEEP值 ,观察不同PEEP对ARDS患者血流动力学和氧代谢、肺气体交换和肺机械力学的影响。结果 :8例患者的准静态肺顺应性曲线均存在Pinf ,为 (11.0± 3 .2 )cmH2 O(1cmH2 O =0 .0 98kPa)。PEEP从Pinf-4增加到Pinf + 6时 ,动脉氧分压 (PaO2 )、动脉氧饱和度 (SaO2 )、平均气道压 (Pm)和气道峰值压 (PIP)均显著增加 (P <0 .0 5 )。与Pinf比较 ,Pinf -4时 ,SaO2 显著降低 ,Pinf+ 2、Pinf+ 4和Pinf+ 6时 ,SaO2 显著增加(P <0 .0 5 ) ;Pinf + 6时 ,心脏指数 (CI)显著降低 (P <0 .0 5 ) ,氧输送 (DO2 )无显著性差异 ,但当PEEP高于Pinf或低于Pinf -2时 ,CI与DO2 均呈降低趋势。与Pinf+ 6相比 ,Pinf-2时动态顺应性显著增高。结论 :ARDS患者机械通气时 ,以低流速法测定的准静态肺顺应性曲线为依据 ,Pinf-2或Pinf为最佳PEEP ,可获得最大DO2 。

Objective Static pressure volume curve were determined by low flow technique to predict the best positive end expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS).Methods Eight patients satisfying ARDS criteria were entered into the study group.Static lung P-V curves were determined.On static P-V curve,different PEEP levels were set as lower inflection pressure (Pinf),Pinf-2,Pinf-4,Pinf+2,Pinf+4 and Pinf+6,effects of which on hemodynamics,oxygen metabolism lung mechanics and gas exchange were compared.Results Pinf of static lung P-V curves was (11.0 ± 3.2) cmH 2O(1?cmH 2O=0.098?kPa).When PEEP increased from Pinf-4 to Pinf+6,partial pressure of arterial oxygen,saturation of arterial oxygen (SaO 2),peak inspiratory pressure and mean airway pressure increased significantly ( P <0.05).Compared with PEEP at Pinf,SaO 2 reduced markedly at Pinf-4 levels,on the other hand,increased significantly at Pinf+2,Pinf+4 and Pinf+6 levels ( P <0.05).Cardiac index reduced notably at Pinf+6 level( P <0.05).Oxygen delivery didnt changed significantly,but reduced when PEEP was lower than Pinf-2 or higher than Pinf.Compared with PEEP at Pinf+6,dynamic compliance improved markedly at Pinf-2( P <0.05).Conclusion When ARDS patients are treated with mechanical ventilation,Pinf-2 or Pinf of static lung P-V curve may yield the best PEEP and the maximum DO 2 may be obtained.