左室舒张功能不全对机械通气撤机结果的预测价值

Predictive value of left ventricular diastolic dysfunction on mechanical ventilation weaning

目的探讨左室舒张功能不全对左室射血分数（LVEF）〉0．50患者机械通气撤机结果的预测价值。方法采用回顾性病例对照研究方法，分析2014年6月至2016年12月中日友好医院外科重症加强治疗病房（ICU）收治的65例LVEF〉0．50，且机械通气时间至少持续48h后撤机患者的临床资料。收集患者在进行自主呼吸试验（SBT）前的基本资料及超声心动图检查结果，通过二尖瓣口血流充盈指标分析患者左室舒张功能与撤机结果的可能关系。根据超声心动图左室舒张功能分级标准将患者分为左室舒张功能正常组、轻度舒张功能不全（1级）组和中至重度舒张功能不全（2～3级）组，比较各组间患者的撤机结果；根据撤机结果将患者分为撤机成功组和撤机失败组，比较两组间患者的基本资料及左室舒张功能指标。采用受试者工作特征曲线（ROC）评估左室舒张功能对重症患者撤机结果的预测价值。结果65例患者最终均纳入分析，撤机失败28例（43．1％），其中22例为首次SBT失败，6例为拔除气管导管后48h内再次插管。左室舒张功能正常组31例，轻度舒张功能不全组9例，中至重度舒张功能不全组25例；随左室舒张功能不全逐渐加重，患者撤机失败率逐渐增加，分别为16．1％、44．4％、76．0％（Х^2=20．240，P=0．001）。与撤机成功者相比，撤机失败者左室舒张功能不全主要表现为E波下降时间（DTE）显著缩短（s：180．4±5．1比196．8±4．0，t=2．567，P=0．013），左室二尖瓣口舒张早期／晚期充盈速度比值（E／A）显著升高（1．47±0．08比1．14±0．05，t=3．827，P=0．000），侧壁部、间隔部及平均左室二尖瓣口舒张早期充盈速度／二尖瓣环舒张早期最大运动速度比值（E／Em）均显著升高（10．26±0．52比7．28±0．41，t=4．535，P=0．000；10．08±0．58比8．16±0．40，t=2．797，P=0．007；10．17±0．48比7．72±0．35，t=4．231，P=0．000），同时临床指标浅快呼吸指数（RSBI）亦明显升高（61．7±3．6比50．6±2．7，t=2．507，P=0．015）。ROC曲线分析结果显示，SBT前的左室舒张功能指标对撤机结果有较大预测价值，其中E／A和侧壁部E／Era的预测价值最大，ROC曲线下面积（AUC）分别为0．81±0．06和0．85±0．06，明显高于RSBI（AUC为0．70±0．07）；当临界值为E／A〉1．2和侧壁部E／Em〉7．9时，敏感度分别为82．6％和9113％，特异度分别为81．4％和80．7％；二者联合预测撤机结果的AUC为0．86±0．05，敏感度为78．3％，特异度为93．6％。结论左室舒张功能不全对LVEF〉0．50患者的撤机结果有预测价值；SBT前E／A〉1．2联合侧壁部E／Em〉7．9对撤机失败的预测价值较高。

Objective To investigate the predictive value of left ventricular diastolic function on mechanical ventilation weaning in patients with left ventricular ejection fraction （LVEF） 〉 0.50. Methods A retrospective case control study was conducted. Sixty-five patients with LVEF 〉 0.50 undergoing mechanical ventilation for more than 48 hours admitted to surgery intensive care unit （ICU） of China-Japan Friendship Hospital from June 2014 to December 2016 were enrolled. The clinical data and parameters of eehocardiography before spontaneous breathing trial （SBT） were collected. The possible relationship between left ventricular diastolic function and the results of weaning was analyzed according to analysis of blood flow filling parameters of mitral valve orifice. According to the grading standard of left ventrieular diastolic function, the patients were divided into normal, mild （level 1） and moderate to severe （level 2-3） groups, and the outcomes of weaning were compared among the groups. Then patients were also divided into two groups of weaning successfully and weaning failure, and the clinical data and left ventricular diastolic function parameters of patients were compared between the two groups. The predictive value of left ventricular diastolic function on results of weaning was evaluated with receiver operating characteristic curve （ROC）. Results Sixty-five patients were enrolled and 28 patients （43.1%） failed weaning, 22 patients failed the first SBT and 6 required reintubation within 48 hours, 31 of the patients presented normal left ventricular diastolic function, 9 of patients presented mild diastolic dysfunction, and 25 of them presented moderate to severe diastolic dysfunction. So with the gradual increase of the severity of diastolic dysfunction, the rate of weaning failure was gradually increased, which was 16.1%, 44.6% and 76.0% respectively （ Х^2 = 20.240, P = 0.001）. Patients who failed weaning presented evidence of increased left ventricular filling pressures at pre-SBT, by demonstrating decreased deceleration time of E （DTE, s： 180.4 ± 5.1 vs. 196.8 ± 4.0, t = 2.567, P = 0.013）, increased left ventrieular mitral valve diastolic early and late filling velocity ratio （E/A： 1.47± 0.08 vs. 1.14±0.05, t = 3.827, P = 0.000）, increased lateral, septal and averaged left ventricular mitral valve diastolic early velocity and maximal velocity of mitral annulus in early diastolic velocity ratio （E/Em： 10.26±0.52 vs. 7.28±0.41, t = 4.535, P = 0.000; 10.08±0.58 vs. 8.16±0.40, t = 2,797, P = 0.007; 10.17±0.48 ± 7.72±0.35, t = 4.231, P = 0.000）, and the rapid shallow breathing index （RSBI） was also increased significantly （61.7±3.6 vs. 50.6±2.7, t = 2.507, P = 0.015）. It was shown by ROC curve analysis that the basic left ventrieular diastolic function at pre-SBT had the diagnostic performance in predicting the outcome of weaning from mechanical ventilation, especially E/A and lateral E/Em. Pre-SBT values of E/A greater than 1.2 and lateral E/Em greater than 7.9 predicted weaning failure with an area under the ROC curve （AUC）, sensitivity, and specificity of 0.81±0.06 and 0.850.06, 82.6% and 91.3%, 81.4% and 80.7%, respectively, and the AUC was higher than RSBI （0.70±0.07）. The AUC of combination of E/A 〉 1.2 and lateral E/Em 〉 7.9 predicting weaning failure was 0.86±0.05 with a sensitivity of 78.3% and a specificity of 93.6%. Conclusions The resuhs suggest that left ventricular diastolic dysfunction is significantly associated with weaning outcome in critical patients with LVEF 〉 0.50. The combination of E/A ratio greater than 1.2 and E/Em ratio greater than 7.9 may identify patients at high risk of weaning failure.