无创通气在机械通气撤离中的作用

Evaluation of the effectivenesss of noninvasive positive pressure ventilation as a weaning strategy in patients with acute respiratory failure

目的探讨无创通气（Noninvasive positive pressure Ventilation，NPPV）在多种原因导致的急性呼吸衰竭机械通气患者撤机流程中的有效性。方法前瞻性分析2007年1月至2008年12月浙江大学医学院附属邵逸夫医院ICU入选的71例急性呼吸衰竭机械通气患者。经气管插管机械通气治疗48h后，达到临床撤机条件，但未能完成自主呼吸试验，排除NPPV禁忌证，将患者随机（随机数字法）分成无创通气序贯撤机（NPPV组，n=36）和传统撤机方法（IPPV组，n=35）两组。NPPV组拔管前予提高压力支持水平休息30min，拔管后立即给予NPPV作为撤机方法；IPPV组传统方法撤机。观察两组患者自主呼吸试验前后呼吸力学参数、动脉血气、循环指标的变化，以及分组后两组机械通气2h后的心肺参数，同时比较两组患者的转归。结果分组后机械通气2h后心肺参数差异无统计学意义。与IPPV组相比，NPPV组机械通气时间、ICU住院时间、总住院时间明显缩短，分别为[（14．88±3．76）dvs．（20．68±2．79）d，P〈0．01）；（14．16±3．45）dVS．（2．57±7．71）d，P〈0．01）；IPPV组分别为（23．39±5．19）d vs．（33．89±8．58）d，P〈0．01）]，NPPV组并发症发生率明显低于IPPV组（22．9％VS．72．2％，P〈0．01），特别是肺部感染发生率较低（6．1％vs．36．1％，P〈0．01）。结论NPPV适用于多种原因导致的呼吸衰竭的撤机过程。把握无创通气NPPV的适应证，以及在撤机过程中及早进行NPPV干预，可以提高NPPV在序贯撤机中的成功率。

Objective To evaluate the effectiveness of noninvasive positive pressure ventilation（NPPV） as a weaning strategy in patients with acute respiratory failure after failure to wean from invasive positive pressure ventilation （IPPV）. Method A prospective randomized and controlled clinical trial of weaning of IPPV was carried out in patients mechanically ventilated in mode of IPPV for more than 48 hours with failure in a spontaneous breathing trial （SBT： PSV 6 cmH20）. Patients with contraindications to NPPV were excluded. After failure the SBT, patients were randomly divided （random number） in two groups. Patients in NPPV group were extubated after being ventilated with high pressure support for 30 minutes and then placed on NPPV. Patients in IPPV group were weaned following conventional procedure. Arterial blood gases, maximal inspiratory pressure, respiratory rate, tidal volume, rapid shallow breathing index, heart rate, arterial blood pressure, and peripheral oxygen saturation were measured before and after failing the SBT. The rate of complications, including pneumonia and tracheotomy duration mechanical ventilation, days of hospital stay and outcome were observed. Findings of the two groups were compared using the Student t test and the chi-square test. Results The percentage of complications in the NPPV group was lower （22.9% versus 72.2%, P 〈 0.01） ,with lower incidences of pneumonia （6.1% ,36.1% ; P〈 0.01 ） and tracheotomy. Compared between the two groups, days of ICU stay （ 14.16 （ 3.45 ） d vs. 22.57 （7.71 ） d; P 〈 0.01） and total days of mechanical ventilation （ 14.88 ± 3.76 days vs. 20.68 ± 2.79 days, P 〈 0.01 ） of NPPV group are shorter than IPPV group. Condusions NPPV is a good alternative to the mechanically ventilated patients who fail in initial weaning attempts. The key to successful NPPV weaning is the proper selection of weaning candidates and using NPPV as soon as possible after extubation.