Elbehairy Amany F, Webb Katherine A, Laveneziana Pierantonio, Domnik Nicolle J, Neder J Alberto, O'Donnell Denis E
Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada; Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt; National Heart and Lung Institute, Faculty of Medicine, Imperial College London, UK.
Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada.
Respir Physiol Neurobiol. 2018 Jun;252-253:64-71. doi: 10.1016/j.resp.2018.03.012. Epub 2018 Mar 22.
This randomized, double-blind, crossover study aimed to determine if acute treatment with inhaled bronchodilators, by improving regional lung hyperinflation and ventilation distribution, would reduce dead space-to-tidal volume ratio (V/V); thus contributing to improved exertional dyspnea in COPD. Twenty COPD patients (FEV = 50 ± 15% predicted; mean ± SD) performed pulmonary function tests and symptom-limited constant-work rate exercise at 75% peak-work rate (with arterialized capillary blood gases) after nebulized bronchodilator (BD; ipratropium 0.5mg + salbutamol 2.5 mg) or placebo (PL; normal saline). After BD versus PL: Functional residual capacity decreased by 0.4L (p = .0001). Isotime during exercise after BD versus PL (p < .05): dyspnea decreased: 1.2 ± 1.9 Borg-units; minute ventilation increased: 3.8 ± 5.5 L/min; IC increased: 0.24 ± 0.28 L and V increased 0.19 ± 0.16 L. There was no significant difference in arterial CO tension or V/V, but alveolar ventilation increased by 3.8 ± 5.5 L/min (p = .02). Post-BD improvements in respiratory mechanics explained 51% of dyspnea reduction at a standardized exercise time. Bronchodilator-induced improvements in respiratory mechanics were not associated with reduced wasted ventilation - a residual contributory factor to exertional dyspnea during exercise in COPD.
这项随机、双盲、交叉研究旨在确定吸入性支气管扩张剂的急性治疗是否通过改善局部肺过度充气和通气分布来降低死腔与潮气量之比（V/V），从而有助于改善慢性阻塞性肺疾病（COPD）患者的运动性呼吸困难。20例COPD患者（预测FEV₁=50±15%；均值±标准差）在雾化吸入支气管扩张剂（BD；异丙托溴铵0.5mg+沙丁胺醇2.5mg）或安慰剂（PL；生理盐水）后，进行了肺功能测试以及在75%峰值工作率下的症状限制恒定工作率运动（同时采集动脉化毛细血管血气）。BD组与PL组相比：功能残气量减少了0.4L（p=0.0001）。BD组与PL组运动期间的等时数据（p<0.05）：呼吸困难减轻：1.2±1.9 Borg单位；分钟通气量增加：3.8±5.5L/min；吸气量增加：0.24±0.28L，潮气量增加0.19±0.16L。动脉血二氧化碳分压或V/V无显著差异，但肺泡通气量增加了3.8±5.5L/min（p=0.02）。在标准化运动时间，BD治疗后呼吸力学的改善解释了呼吸困难减轻的51%。支气管扩张剂引起的呼吸力学改善与无效通气减少无关——无效通气是COPD患者运动期间运动性呼吸困难的一个残留促成因素。
