体外膜氧合治疗重症急性呼吸衰竭的临床疗效分析

The experience of extracorporeal membrane oxygenation for severe acute respiratory failure in adults

目的观察体外膜氧合（ECMO）治疗重症急性呼吸衰竭的临床疗效，探讨影响预后的相关因素。方法采用前瞻性观察研究的方法，收集并分析2009年11月至2011年12月北京朝阳医院呼吸重症监护病房（RICU）因重症急性呼吸衰竭接受ECMO治疗的患者临床资料。统一设计表格，记录患者一般资料、ECMO前一般情况、ECMO期间血气分析、血流动力学、机械通气以及ECMO辅助并发症等，主要终点观察指标为ECMO治疗3个月内死亡或严重致残。运用SPSS16．0软件对数据进行统计分析。结果共有25例患者接受ECMO治疗，其中16例纳入本研究，男13例，女3例，年龄22～64岁，平均（454-14）岁。所有患者在ECMO治疗前均已行有创通气，平均（724-64）h，其中8例曾应用无创正压通气的中位时间为55（10～114）h。ECMO前6h内最低氧合指数平均为（544-18）mmHg（1mmHg=0．133kPa），呼气末正压（PEEP）为（11±6）cmH2O（1cmH2O=0．098kPa），Murray急性肺损伤评分为3．6±0．5，血乳酸为（2．5±2．0）mmol／L，血白细胞计数为（16±6）×10^9／L，急性生理与慢性健康状态评分Ⅱ（APACHE1I）为17±8。所有患者均采用静脉-静脉ECMO（VV—ECMO）方式，ECMO前、运行后2h机械通气参数及呼吸力学监测情况：吸入氧浓度分别为1．00和0．55±0．21，PEEP分别为（11±6）和（9±6）cmH2O，潮气量分别为（6．8±2．2）和（4．4±2．0）ml／kgPBW，气道峰压分别为（27±8）和（24±7）cmH20，呼吸频率分别为（37±10）和（23-4-10）~．X／min。与ECMO前6h相比，ECMO后24及48h动脉血气指标（pH值、Pa02和PaC02）均明显改善（均P〈0．05）。ECMO支持治疗时间为2—41d，平均（9．7±9．6）d。16例患者中10例成功撤离ECMO，2例在撤离ECMO后死亡；另外6例患者中3例在ICU内死亡，3例放弃治疗而死亡。ECMO治疗3个月无伤残存活8例。Cox多元回归分析显示ECMO运行前6h内氧合指数越低、血白细胞计数越高者，预后越差（RR值分别为0．733和1．701，均P〈0．05）。结论VV-ECMO是重症急性呼吸衰竭的潜在有效治疗手段，ECMO治疗前患者氧合指数、血白细胞计数可能与预后相关。

Objective To summarize the experience of extracorporeal membrane oxygenation （ECMO） for patients with severe acute respiratory failure in adults and to investigate the factors associated with death. Methods The clinical data of patients with severe acute respiratory failure supported with ECMO in respiratory intensive care unit of Beijing Chaoyang Hospital from November 2009 to December 2011 were prospectively collected and analyzed. The data included general condition before EMCO, blood gas analysis, hemodynamics, ventilator settings of mechanical ventilation and complications during ECMO. The primary outcome was death or severe disability within 3 months. Statistical software of SPSS （version 16. 0） was used for data analysis. Results Twenty-five patients with severe respiratory failure received ECMO treatment, of which 16 patients were analyzed. The mean age was （45± 14） years old （range, 22 -64 years old）. Thirteen patients were male. Before ECMO, all of the patients were treated with invasive positive pressure ventilation for （72 ± 64） hours. Eight patients had been treated with noninvasive ventilation for a median of 55 （ 10 - 114 ） hours. Patients had severe respiratory failure despite advanced mechanical ventilator support. The mean PaO2/fraction of inspired oxygenation （ FiO2 ） ratio was （ 54 ± 18 ） mm Hg （1 mm Hg =0. 133 kPa）, positive end-expiratory pressure （PEEP） was （11 ± 6） cm H2O（ 1 cm H2O = 0. 098 kPa）, Murray lung injury score was 3.6 ±0. 5, serum lactate was （2. 5 ±2. 0） retool/L, serum white blood cell count was （16 ± 6） ×10^9/L, and APACHE Ⅱ score was 17 ± 8. All of the patients were treated with venous-venous ECMO （VV-ECMO）. The change of mechanical ventilation settings were （pre-ECMO vs 2 hours post-ECMO） ： FiO2 1.0 vs 0.55±0.21, PEEP （11 ±6） vs （9±6） cm H2O, VT（6. 8 ±2.2） vs （4. 4 ±2. 0） ml/kg PBW, peak airway pressure （27 ±8） vs （24 ±7） cm H2O,respiratory rate （37 ± 10） vs （23 ± 10） breaths/min. Arterial blood gas, including pH, PaO2 and PaCO2 were significantly improved after ECMO running 24 and 48 hours （P 〈 O. 05）. The mean VV-ECMO support interval was （9. 7 ± 9. 6） days （range, 2-41 days）. Ten patients were successfully weaned from ECMO, of whom 2 died in ICU. Three patients died during ECMO, while another 3 patients died after withdrawal of further treatment. Eight patients survived to 3 months without severe disability. In a multi-variate Cox regression model, pre-ECMO factors including lower PaO2/FiO2 and increasing white blood cell count were associated with increased risks of death （ RR was 0. 733,1. 701 respectively, both P values 〈 0. 05 ）. Conclusions VV-ECMO is a potentially effective approach for severe acute respiratory failure. PaO2/FiO2 and white blood cell count pre- ECMO may be the risk factors for poor outcome.