Faculty of Medicine and Dentistry, Division of Pulmonary Medicine, University of Alberta, Edmonton, Alberta, Canada.
Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.
J Appl Physiol (1985). 2020 Apr 1;128(4):925-933. doi: 10.1152/japplphysiol.00890.2019. Epub 2020 Mar 12.
Patients with mild chronic obstructive pulmonary disease (COPD) demonstrate resting pulmonary vascular dysfunction as well as a blunted pulmonary diffusing capacity (DLCO) and pulmonary capillary blood volume (V) response to exercise. The transition from the upright to supine position increases central blood volume and perfusion pressure, which may overcome microvascular dysfunction in an otherwise intact alveolar-capillary interface. The present study examined whether the supine position normalized DLCO and V responses to exercise in mild COPD. Sixteen mild COPD participants and 13 age-, gender-, and height-matched controls completed DLCO maneuvers at rest and during exercise in the upright and supine position. The multiple -DLCO method was used to determine DLCO, V, and membrane diffusion capacity (D). All three variables were adjusted for alveolar volume (DLCOAdj, VAdj, and DAdj). The supine position reduced alveolar volume similarly in both groups, but oxygen consumption and cardiac output were unaffected. DLCOAdj, DAdj, and VAdj were all lower in COPD. These same variables all increased with upright and supine exercise in both groups. DLCOAdj was unaffected by the supine position. VAdj increased in the supine position similarly in both groups. DAdj was reduced in the supine position in both groups. While the supine position increased exercise VAdj in COPD, the increase was of similar magnitude to healthy controls; therefore, exercise V remained blunted in COPD. The persistent reduction in exercise DLCO and V when supine suggests that pulmonary vascular destruction is a contributing factor to the blunted DLCO and V response to exercise in mild COPD. Patients with mild chronic obstructive pulmonary disease demonstrate a combination of reversible pulmonary microvascular dysfunction and irreversible pulmonary microvascular destruction.
患有轻度慢性阻塞性肺疾病（COPD）的患者表现出静息肺血管功能障碍，以及运动时肺扩散能力（DLCO）和肺毛细血管血容量（V）反应减弱。从直立位到仰卧位的转变会增加中心血容量和灌注压，这可能会克服肺泡毛细血管界面完整但微血管功能障碍的情况。本研究旨在探讨仰卧位是否能使轻度 COPD 患者的运动时 DLCO 和 V 反应正常化。16 名轻度 COPD 参与者和 13 名年龄、性别和身高匹配的对照者在直立和仰卧位下完成了静息和运动时的 DLCO 检查。采用多-DLCO 法测定 DLCO、V 和膜扩散能力（D）。所有三个变量均根据肺泡容积进行调整（DLCOAdj、VAdj 和 DAdj）。两组的仰卧位均使肺泡容积相似地降低，但耗氧量和心输出量不受影响。COPD 患者的 DLCOAdj、DAdj 和 VAdj 均较低。这三个变量在两组中均随着直立和仰卧运动而增加。DLCOAdj 不受仰卧位影响。VAdj 在两组仰卧位中均增加。DAdj 在两组仰卧位中均降低。虽然仰卧位增加了 COPD 患者的运动 VAdj，但增加幅度与健康对照组相似；因此，COPD 患者的运动 V 仍然减弱。仰卧位时运动时 DLCO 和 V 持续降低表明，肺血管破坏是导致轻度 COPD 运动时 DLCO 和 V 反应减弱的一个因素。患有轻度慢性阻塞性肺疾病的患者表现出可逆性肺微血管功能障碍和不可逆性肺微血管破坏的组合。
