氧负荷试验对评估ECMO治疗的心源性休克患者预后的价值

Prognostic value of oxygen challenge test for patients with cardiogenic shock receiving extracorporeal membrane oxygenation

目的探讨氧负荷试验用于评估因心源性休克行体外膜肺氧合（ECMO）治疗患者的预后价值。方法回顾性分析2012年6月至2017年5月南京医科大学附属无锡人民医院重症医学科（ICU）收治的78例接受静脉-动脉（V-A）ECMO治疗的心源性休克患者的临床资料。所有患者ECMO治疗后6 h均采用经皮氧分压（PtO2）监测和氧负荷试验。记录患者的基本资料，开始ECMO治疗当天的急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分、序贯器官衰竭评分（SOFA）、左室射血分数（LVEF）、平均动脉压（MAP），ECMO治疗6 h的动脉血气分析指标、血管活性药物剂量、基础PtO2、10 min氧负荷值（OCT10）、氧负荷指数（OCI），以及60 d内ECMO支持时间、机械通气时间和参数、主动脉内球囊反搏术（IABP）应用情况等。根据ECMO治疗后60 d的存活情况将患者分为存活组和死亡组，比较两组各指标的差异；采用受试者工作特征曲线（ROC）分析OCT10、OCI等对预后的判断价值；根据OCT10、OCI的最佳临界值分组，绘制Kaplan-Meier生存曲线，比较60 d累积生存率；采用多因素Logistic回归分析影响预后的危险因素。结果最终纳入67例患者，存活组31例，死亡组36例。与存活组比较，死亡组APACHEⅡ评分、SOFA评分、IABP应用比例更高，PtO2、OCT10、OCI更低，ECMO支持时间和机械通气时间更长，但两组性别、年龄、原发病构成、LVEF、MAP、机械通气参数、血管活性药物剂量、血气分析指标等比较差异无统计学意义。OCT10、OCI、APACHEⅡ评分及SOFA评分对患者60 d死亡均有预测价值，OCT10的ROC曲线下面积（AUC）为0.866±0.042，95%可信区间（95%CI）=0.760~0.937；OCI的AUC为0.829±0.051，95%CI=0.717~0.910；APACHEⅡ评分的AUC为0.860±0.043，95%CI=0.754~0.933；SOFA评分的AUC为0.821±0.049，95%CI=0.708~0.904（均P〈0.01）。以OCT10≥70.0 mmHg （1 mmHg=0.133 kPa）为最佳临界值时，预测预后的敏感度为91.67%，特异度为67.74%；以OCI≥0.68为最佳临界值时，预测预后的敏感度为88.68%，特异度为71.58%。依据OCT10和OCI最佳临界值将患者分组，高OCT10组60 d累积生存率显著高于低OCT10组〔58.06%（18/31）比36.11%（13/36），χ2=5.425，P=0.020〕；高OCI组60 d累积生存率显著高于低OCI组〔55.17%（16/29）比39.47%（15/38），χ2=5.119，P=0.024〕。多因素Logistic回归分析显示，OCT10和OCI均是患者60 d死亡的独立危险因素〔OCT10的优势比（OR）=0.883，95%CI=0.791~0.965，P=0.006；OCI的OR=0.011，95%CI=0.001~0.087，P=0.005〕。结论氧负荷试验可以用于评估接受ECMO支持的心源性休克患者的预后。

ObjectiveTo investigate the prognostic value of oxygen challenge test （OCT） for patients with cardiogenic shock receiving extracorporeal membrane oxygenation （ECMO）.MethodsA retrospective analysis was conducted. Seventy-eight patients diagnosed with cardiogenic shock receiving veno-arterial （V-A） ECMO admitted to Department of intensive care unit （ICU） of Wuxi People＇s Hospital Affiliated to Nanjing Medical University from June 2012 to May 2017 were enrolled. Ten-minute OCT was implemented by transcutaneous oximetry at 6 hours after ECMO initiation. The basic data of patients （gender, age, primary disease）; the acute physiology and chronic health evaluation Ⅱ （APACHE Ⅱ） score, sequential organ failure assessment （SOFA） score, left ventricular ejection fraction （LVEF）, mean arterial pressure （MAP） at the start of ECMO treatment; arterial blood gas analysis index, dose of vasoactive agents, transcutaneous oxygen pressure （PtO2）, 10-minute OCT value （OCT10）, oxygen challenge index （OCI） at 6 hours after ECMO initiation; and the ECMO support time, duration of mechanical ventilation and its parameters, and application of intra-aortic balloon pump （IABP） within 60 days were recorded. Patients were divided into the survival group and the death group according to their 60-day mortality status, and the differences between the two groups were compared. Receiver operating characteristic curve （ROC） analysis was used to analyze the prognostic value of OCT10 and OCI. According to the best boundary value of OCT10 and OCI, Kaplan-Meier survival curve was drawn and the 60-day cumulative survival rate was compared. The risk factors affecting prognosis were analyzed by multivariate Logistic regression.ResultsSixty-seven patients were finally enrolled in the study, with 31 in the survival group and 36 in the death group. Compared with the survival group, APACHE Ⅱ score, SOFA score, use of IABP in death group were higher, PtO2, OCT10 and OCI were lower, and duration of ECMO and ventilation were longer, but there was no significant difference in gender, age, primary disease, LVEF, MAP, ventilator settings, dose of vasoactive agents, or results of arterial blood gas between the two groups. OCT10, OCI, APACHE Ⅱ score and SOFA score were predictive values for 60-day deaths, and the area under ROC curve （AUC） of OCT10 was 0.866±0.042 [95% confidence interval （95%CI） = 0.760-0.937], the AUC of OCI was 0.829±0.051 （95%CI = 0.717-0.910）, the AUC of APACHE Ⅱ score was 0.860±0.043 （95%CI = 0.754-0.933）, and the AUC of SOFA score was 0.821±0.049 （95%CI = 0.708-0.904） （all P 〈 0.01）. The cut-off point for OCT10 was ≥70.0 mmHg （1 mmHg = 0.133 kPa） with the sensitivity of 91.67% and the specificity of 67.74%. The cut-off point for OCI was ≥0.68 with the sensitivity of 88.68% and the specificity of 71.58%. According to the cut-off point for OCT10 or OCI, the 60-day cumulative survival rate of patients with high OCT10 was significantly higher than that of low OCT10 [58.06% （18/31） vs. 36.11% （13/36）, χ2 = 5.425, P = 0.020]; the survival rate in high OCI group was significantly higher than that in low OCI group [55.17% （16/29） vs. 39.47% （15/38）, χ2 = 5.119, P = 0.024]. It was shown by multivariate Logistic regression that OCT10 [odds ratio （OR） = 0.883, 95%CI = 0.791-0.965, P = 0.006] and OCI （OR = 0.011, 95%CI = 0.001-0.087, P = 0.005） were independent risk factors for 60-day mortality.ConclusionOCT could predict the prognosis of patients with cardiogenic shock receiving ECMO.