Jubran A, Parthasarathy S
Associate Professor, Division of Pulmonary and Critical Care Medicine, Edward Hines Jr Veterans Affairs Hospital, Hines, IL 60141, USA.
Respir Care Clin N Am. 2000 Sep;6(3):385-405;v. doi: 10.1016/s1078-5337(05)70078-2.
Patients who fail a weaning trial develop hypercapnia as a result of alveolar hypoventilation, which, in turn, is caused by an imbalance between the respiratory muscle load and capacity. In some patients, especially those with obstructive lung diseases, respiratory muscle performance is impaired as a result of dynamic hyperinflation and paradoxical motion of the rib cage and abdomen. Worsening of pulmonary mechanics causes further embarrassment of the respiratory muscles and can lead to marked alterations of oxygen use by the peripheral tissues. The development of rapid shallow breathing together with worsening of pulmonary mechanics results in inefficient clearance of COcf152cf1 during a failed weaning attempt.
撤机试验失败的患者会因肺泡通气不足而出现高碳酸血症，而肺泡通气不足又是由呼吸肌负荷与能力失衡所致。在一些患者中，尤其是患有阻塞性肺疾病的患者，由于动态肺过度充气以及胸廓和腹部的矛盾运动，呼吸肌功能会受到损害。肺力学的恶化会进一步使呼吸肌窘迫，并可能导致外周组织氧利用的显著改变。在撤机尝试失败期间，快速浅呼吸的出现以及肺力学的恶化会导致二氧化碳清除效率低下。
