Objective To study diaphragmatic strength in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) during mechanical ventilation (MV), and to explore the predictive value of maximal transdiaphragm pressure (Pdi max) for successful extubation. Methods A prospective study was conducted. Twenty-one patients with AECOPD receiving MV admitted to intensive care unit (ICU) of Shanghai East Hospital of Tongji University of School Medicine from February 2015 to May 2017 were enrolled. Pdi max value was measured by using esophageal and gastric balloon catheters within 24 hours of intubation until the day the patient underwent extubation or died. In addition, the C-reactive protein (CRP), serum albumin (Alb) and prealbumin (PA) during MV were recorded. Pearson correlation was used to analyze the correlations between Pdi max and CRP, Alb and PA. The receiver operating characteristic curve (ROC) was used to cumulate Pdi max value of the successful weaning. Results Tracheotomy was done in 2 patients, and 2 patients quit the study. The remaining 17 patients were included in the investigative protocol. Six of the 17 patients died and 11 patients were successfully extubated. ① Mean Pdi max decreased progressively over time in 17 patients of AECOPD during MV. There were no significant changes in Pdi max at 1-2 days of MV. Mean Pdi max at 7 days was significantly lower than that at 3 days [cmH2O (1 cmH2O = 0.098 kPa): 20.2±4.2 vs. 28.1±4.4, P < 0.01]. By the end of the evaluation period at 11 days of MV, mean Pdi max decreased about 38.7% to the 1 day of MV (cmH2O: 19.8±4.7 vs. 32.3±3.9, P < 0.01). During MV, CRP, Alb and PA showed a downward trend. ② Mean Pdi max and the Pdi max before extubation in patients with difficulty extubation from MV was lower than that in successful weaning [Mean Pdi max (cmH2O): 25.2±5.4 vs. 28.9±5.8, Pdi max before extubation (cmH2O): 16.9±2.8 vs. 26.8±6.6, both P < 0.01]. ③ There was significantly negative correlation between Pdi max value and CRP (r = -0.799, P = 0.000). There was significantly positive correlation between Pdi max value and serum Alb (r = 0.613, P = 0.008) and PA (r = 0.661,P = 0.004). ④ ROC curve analysis showed that the area under the ROC curve (AUC) for predicting weaning success in the patients with AECOPD was 0.902. The sensitivity of the diagnosis was 81.8% and the specificity was 100% when cut-off value of Pdi max was 23.2 cmH2O. Conclusions MV induced the reduction of diaphragmatic contractility in a time-dependent manner. The Pdi max in patients with difficult extubation from MV was lower than that in successful weaning. The Pdi max could be a parameter to predict the successful extubation in patients with AECOPD during MV.%目的 观察慢性阻塞性肺疾病急性加重(AECOPD)患者在机械通气(MV)条件下膈肌收缩强度的变化,探讨最大跨膈压(Pdi max)对AECOPD患者脱机结果的预测价值.方法 采用前瞻性研究方法,选择2015年2月至2017年5月同济大学附属东方医院重症加强治疗病房(ICU)收治的21例AECOPD且接受MV的患者.入选患者在MV 24 h内开始采用胃食道囊管法测量Pdi max,直至拔管或死亡;记录患者MV期间C-反应蛋白(CRP)、血清白蛋白(Alb)和前白蛋白(PA)的变化.采用Pearson相关法分析Pdi max与CRP、Alb和PA的相关性;绘制受试者工作特征曲线(ROC),分析预测AECOPD患者脱机成功的Pdi max值.结果 研究期间2例患者行气管切开、2例中途退出研究,最终17例患者纳入分析,其中6例死亡,11例成功脱机.① 17例AECOPD患者MV期间Pdi max呈逐渐下降趋势;MV 1~2 d Pdi max 变化不明显,7 d时较3 d时明显下降〔cmH2O (1 cmH2O=0.098 kPa):20.2±4.2比28.1±4.4,P<0.01〕,11 d时较1 d时下降约38.7% (cmH2O:19.8±4.7比32.3±3.9,P<0.01).MV期间CRP、Alb和PA均呈下降趋势.② 困难脱机患者MV期间平均Pdi max及拔管前Pdi max均明显低于成功脱机患者〔平均Pdi max(cmH2O):25.2±5.4比28.9±5.8,拔管前Pdi max(cmH2O):16.9±2.8比26.8±6.6,均P<0.01〕.③ 相关分析显示:MV期间Pdi max与CRP呈明显负相关(r=-0.799,P=0.000),与血清Alb(r=0.613,P=0.008)和PA(r=0.661,P=0.004)均呈显著正相关.④ ROC曲线分析显示:Pdi max预测AECOPD患者脱机成功的ROC曲线下面积(AUC)为0.902;当截断值为23.2 cmH2O时,敏感度为81.8%,特异度为100%.结论 AECOPD患者MV期间膈肌收缩强度降低,并随时间延长而加重;困难脱机者膈肌收缩强度低于成功脱机者.Pdi max可能成为预测行MV的AECOPD患者脱机成功的一项指标.
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