分钟通气量恢复时间在慢性阻塞性肺疾病患者撤机中的作用

The minute ventilation recovery time used as a predictor of weaning in patients with chronicobstructive pulmonary disease

目的探讨分钟通气量恢复时间（minuteventilationrecoverytime，VERT）在慢性阻塞性肺疾病（chronicobstructivepulmonarydisease，COPD）患者呼吸机撤离中的预测作用。方法前瞻性研究，入选2008年3月至2012年7月在本院呼吸重症监护病房中进行有创机械通气48h以上的52例COPD患者，所有患者通过自主呼吸实验（spontaneousbreathingtrial，SBT）并准备撤机，在完成SBT后将呼吸机设置恢复到SBT前水平并连续观察25min，得到VERT值，即分钟通气量恢复到SBT前的基础值所用的时间。记录SBT前和SBT结束时的呼吸频率、潮气量、分钟通气量、浅快呼吸指数以及撤机前动脉血气分析指标。根据撤机结果将患者分为成功组40例和失败组12例。用t检验比较两组间VERT及其他指标的差异，用多因素Logistic回归分析探讨撤机结果的相关因素。用ROC曲线评价VERT预测撤机结果的敏感性和特异性。结果两组之间V。RT和SBT结束时呼吸频率差异有统计学意义。多因素Logistic回归结果显示只有VERT与撤机结果存在相关性（b=0．282，P〈0．001）。VERT的ROC曲线下面积0．957（95％CI：0．907—1．008），VERT的cut-off值为10．5min，预测撤机失败的敏感性为1．0，特异性为n85。结论VERT可以作为一个新的撤机指标预测COPD患者撤机结果。VERT测量方法简便，便于临床应用。

Objective To explore the value of minute ventilation recovery time （VERT） as a weaning predictor in mechanically ventilated patients with chronic obstructive pulmonary disease （COPD）. Methods A prospective study was performed from March 2008 to July 2012. Fifty - two COPD patients under mechanical ventilation for more than 48 hours in our RICU tolerated a spontaneous breathing trial （SBT） and were ready for planned extubation. After SBT, these patients were placed back on their pre - SBT ventilator settings for up to 25 minutes, during which VERT was obtained. VERT was defined as the time for minute ventilation to return to baseline measured before SBT. Respiratory rate, tidal volume, minute ventilation and respiratory rate/tidal volume ratio were also obtained before SBT and just after SBT. Arterial blood gas data were measured and recorded before weaning. According to the weaning outcome, the patients were classified as successful group （40 cases） or failed group （ 12 cases）. VERT and other quantitative variables were compared using t test. A multiple logistic regression was performed to explore possible factors associated with the weaning outcome. The sensitivity and specificity of VERT for predictive capacity in weaning were assessed using ROC cure. Results VERT and respiratory rate after SBT were significantly different between two groups. Multiplelogistic regression revealed that VERT was the only predictor associated with weaning outcome （b =0. 282, P 〈 0. 001 ）. The area under ROC curve for VERT was 0. 957 （95% CI： O. 907-1. 008）. With a cut-off value of 10. 5 minutes, the sensitivity and specificity of VERT for predicting weaning failure were 1.0 and 0. 85, respectively. Conclusions VERT may be a new predictor for extubation and determination of mechanical ventilation weaning in patients with COPD. VERT is a variable to be easily measured thereby being conveniently used in clinical practice.