呼吸综合指数预测慢性阻塞性肺疾病急性加重机械通气患者脱机结果的多中心研究

A multicenter study of respiratory multiple index in predicting weaning from mechanical ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease

目的探讨呼吸综合指数（CROP，顺应性、呼吸频率、氧合、压力）对慢性阻塞性肺疾病急性加重（AECOPD）机械通气患者脱机结果的预测价值。方法采用前瞻性多中心研究，选择2010年9月至2012年10月5家三级甲等医院重症监护病房（ICU）215例AECOPD机械通气脱机患者，均因呼吸衰竭失代偿接受经口气管插管机械通气24h以上，意识清楚、合作，均通过30min自主呼吸试验（SBT）。脱机前测定最大吸气压（Plmax），记录气道峰压（Ppeak）、总呼气末正压（PEEPtot）、潮气量（V_T）、呼吸频率（f），检测动脉血气分析记录氧分压（PaO2）和二氧化碳分压（PaCO2），计算实际肺顺应性（Crs）和肺泡氧分压（P_A O2）。代人公式CROP=实际Crs×1／f×PaO2／P_A O2×Plmax，计算得到CROP值，72h内无需再插管为脱机成功。绘制受试者工作特征曲线（ROC线）分析CROP对AECOPD机械通气患者脱机成败的预测价值。结果215例患者中182例脱机成功，33例失败。脱机成功和失败的患者在性别、年龄、急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分等方面比较无统计学差异。失败组患者脱机前PaCO2（mmHg，1mmHg=0．133kPa）明显高于成功组（60．69±10．47比51．24±8．81，P〈0．05），CROP（ml·次-1·min-1）明显低于成功组（10．286±1．392比58．746±7．283，P〈0．01），机械通气时间（d）较成功组明显延长（10．28±3．94比6．21±2．87，P〈0．05）。脱机成功与否的CROP最佳临界值为13．521ml·次-1·min-1，当CROP≥13．521ml·次-1·min-1时预测脱机成功的特异性为91．9％，敏感性为87．9％，阳性预测值为0．97，阴性预测值为0．58；比值比（OR）〈1，提示CROP是影响脱机结局的独立因素。结论对于AECOPD机械通气患者，多数脱机参数有其限制性，而复合参数CROP预测脱机成功的敏感性及特异性均较高，对脱机是否成功有明确的指导价值，CROP≥13．521ml·次-1·min-1时患者脱机成功率高，CROP〈13．521ml·次-1·min-1时患者脱机失败率高。

Objective To study the result of respiratory multiple index （compliance, respiratory rate, oxygenation, pressure, CROP） in predicting weaning from mechanical ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease （AECOPD）. Methods A prospective study was conducted. Two hundred and fifteen patients weaning from mechanical ventilation with AECOPD in intensive care unit （ICU） of five tertiary hospitals from September 2010 to October 2012 were enrolled. All of the AECOPD patients were troubled with respiratory failure and received non-invasive mechanical ventilation for more than 24 hours. They were conscious and cooperative at the time of extubation, and passed the spontaneous breathing trial （SBT） for 30 minutes. Before weaning, the maximal inspiratory pressure （Plmax）, the peak airway pressure （Ppeak）, the total positive end expiratory pressure （PEEPtot）, tidal volume （VT） and respiratory frequency （f） were recorded; the arterial partial pressure of oxygen （PaO2） and arterial partial pressure of carbon dioxide （PaCO2） were detected; the effective compliance of the respiratory system （Crs） and alveolar oxygen pressure （PAO2） were calculated. The above indexes were substituted into the formula： CROP=Crs × 1/f × PaO2 / PAO2 × PImax to get the value of CROP. Successful weaning from mechanical ventilation was defined if there was no indication for intubation within 72 hours. The receiver operating characteristic curve （ROC curve） was drawn to analyze the predict value of CROP on result of weaning from mechanical ventilation in patients with AECOPD. Results In 215 patients, 182 patients successfully weaned from mechanical ventilation, and 33 failed. There were no significant differences in get,tier, age and the acute physiology and chronic health evaluationⅡ （APACHE Ⅱ ） scorebetween the successfully weaned patients and the failed. Before weaning from mechanical ventilation, PaCO2 （ mm Hg, 1 mm Hg=0.133 kPa） in failed group was significantly higher than that in successful group （60.69 ± 10.47 vs. 51.24 ± 8.81, P〈0.05）, the CROP （ml.breath-1.min-1） was significantly lowered （10.286 ±1.392 vs. 58.746 ± 7.283, P〈0.01 ）, and the duration of mechanical ventilation （days） was prolonged （10.28± 3.94 vs. 6.21 ± 2.87, P〈0.05）. The best critical value of CROP which could predict the result of weaning from mechanical ventilation was 13.521 ml.breath-1 .min-1. CROP ≥13.521 ml-breath-1.min-1 had a specificity of 91.9% and sensitivity of 87.9% in predicting extubation succeed. The positive predicted value was 0.97, and the negative predicted value was 0.58 ; Odds ratio （OR） 〈 1, which confirmed that CROP was a strong and independent predictor of extubation. Conclusions For the AECOPD patients received mechanical ventilation, most extubation parameter was limited. Complex parameter of CROP has higher specificity and sensitivity, and has important value in predicting extubation outcome. When CROP≥ 13.521 ml.breath-1. min-1, the successful rate is high, otherwise the rate is low.