Jubran A, Tobin M J
Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA.
Am J Respir Crit Care Med. 1997 Mar;155(3):916-21. doi: 10.1164/ajrccm.155.3.9117026.
In an accompanying article (Jubran, et al., Am. J. Respir. Crit. Care Med. 155:906-915), we report that patients with chronic obstructive pulmonary disease (COPD) who failed a trial of weaning from mechanical ventilation developed worsening of pulmonary mechanics compared with patients who tolerated the trial and were extubated. We wondered whether the greater derangements in pulmonary mechanics in the weaning failure patients are evident ever before undertaking the weaning trial. We measured mechanics of the respiratory system, lung, and chest wall during passive ventilation at usual ventilator settings in 12 patients who went on to fail a weaning trial and in 12 patients who were successfully weaned. No differences in the resistances of the respiratory system, lung, and chest wall were observed between the two groups or when the resistances were separated into the components derived from ohmic resistance and viscoelastic behavior/time-constant inhomogeneities. Likewise, the groups did not differ in terms of static elastance and dynamic intrinsic positive end-expiratory pressure (PEEPi) of the respiratory system and the respective lung and chest wall components or in terms of dynamic elastances of the respiratory system and chest wall. The failure group had a higher dynamic elastance of the lung than the success group (p < 0.01), but the individual values showed considerable overlap among the patients in the two groups so limiting its usefulness in signaling a patient's ability to sustain spontaneous ventilation. Thus, mechanics of the respiratory system and its lung and chest wall components during passive ventilation did not satisfactorily discriminate between patients who failed a weaning trial and those successfully weaned, and, thus, are unlikely to be useful in signaling a patient's ability to tolerate the discontinuation of mechanical ventilation.
在一篇随附文章中（朱布兰等人，《美国呼吸与危重症医学杂志》155:906 - 915），我们报告称，与耐受撤机试验并成功拔管的患者相比，撤机试验失败的慢性阻塞性肺疾病（COPD）患者肺力学出现恶化。我们想知道，在进行撤机试验之前，撤机失败患者肺力学方面更严重的紊乱是否就已明显。我们在常规呼吸机设置下对12例撤机试验失败的患者和12例成功撤机的患者进行被动通气时测量了呼吸系统、肺和胸壁的力学指标。两组之间以及将阻力分为源自欧姆阻力和粘弹性行为/时间常数不均匀性的各成分时，呼吸系统、肺和胸壁的阻力均未观察到差异。同样，两组在呼吸系统以及各自的肺和胸壁成分的静态弹性和动态内在呼气末正压（PEEPi）方面，或者在呼吸系统和胸壁的动态弹性方面也没有差异。失败组的肺动态弹性高于成功组（p < 0.01），但两组患者的个体值有相当大的重叠，因此限制了其在提示患者维持自主通气能力方面的作用。因此，被动通气时呼吸系统及其肺和胸壁成分的力学指标不能令人满意地区分撤机试验失败的患者和成功撤机的患者，所以不太可能用于提示患者耐受机械通气中断的能力。
