Division of Cardiovascular Disease, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Heart Lung Transplant. 2011 Oct;30(10):1133-42. doi: 10.1016/j.healun.2011.03.021. Epub 2011 May 31.
The 6-minute walk test is widely used to characterize activity tolerance and response to therapy in pulmonary arterial hypertension (PAH) but provides little information about cardiopulmonary pathophysiology. The aim of the present study was to determine whether measures of pulmonary gas exchange during relatively light exercise could differentiate between PAH patients and healthy individuals and also stratify disease severity.
The study comprised 40 PAH patients and 25 matched controls. Each completed a sub-maximal exercise test, consisting of 2 minutes of rest, 3 minutes of exercise, and 1 minute of recovery. Ventilation, pulmonary gas exchange, arterial oxygen saturation (Sao(2)), and heart rate were measured throughout using a simplified gas analysis system.
A number of gas exchange variables differentiated PAH patients and controls. End-tidal CO(2) (P(ET)co(2)) and Sao(2) were lower in PAH vs controls (31 ± 7 vs 39 ± 3 mm Hg and 89% ± 5% vs 95% ± 2%, respectively, p < 0.05). Breathing efficiency (V(E)/Vco(2) ratio) was poorer in PAH vs controls (42 ± 10 vs 33 ± 5, p < 0.05). In addition, P(ET)co(2) and V(E)/Vco(2) discriminated between different severities of PAH.
Gas exchange variables obtained during light sub-maximal exercise differentiated PAH patients from healthy controls and also between different severities of PAH. Sub-maximal exercise gas exchange may be a useful end point measure in a PAH population.
6 分钟步行试验广泛用于评估肺动脉高压（PAH）患者的活动耐量和治疗反应，但提供的心肺病理生理学信息有限。本研究旨在确定在相对轻度运动期间的肺气体交换测量值是否能够区分 PAH 患者和健康个体，并对疾病严重程度进行分层。
该研究纳入了 40 名 PAH 患者和 25 名匹配的对照者。每位患者和对照者都完成了一项亚最大运动试验，包括 2 分钟的休息、3 分钟的运动和 1 分钟的恢复期。在整个过程中，使用简化气体分析系统测量通气、肺气体交换、动脉血氧饱和度（Sao2）和心率。
一些气体交换变量可区分 PAH 患者和对照者。与对照者相比，PAH 患者的呼气末二氧化碳（P(ET)co(2))和 Sao2 更低（分别为 31 ± 7 比 39 ± 3mmHg 和 89% ± 5%比 95% ± 2%，p < 0.05）。与对照者相比，PAH 患者的呼吸效率（V(E)/Vco(2) 比值）更差（分别为 42 ± 10 比 33 ± 5，p < 0.05）。此外，P(ET)co(2)和 V(E)/Vco(2) 可区分 PAH 的不同严重程度。
在轻度亚最大运动期间获得的气体交换变量可将 PAH 患者与健康对照者区分开来，并且可区分 PAH 的不同严重程度。亚最大运动气体交换可能是 PAH 人群中的一个有用的终点测量指标。
