Reybrouck T, Mertens L, Schulze-Neick I, Austenat I, Eyskens B, Dumoulin M, Gewillig M
Department of Paediatric and Congenital Cardiology, Gasthuisberg University Hospital, Leuven, Belgium.
Clin Physiol. 1998 Jul;18(4):337-44. doi: 10.1046/j.1365-2281.1998.00109.x.
The purpose of this study was to analyse the ventilatory efficiency for carbon dioxide (CO2) in the assessment of exercise tolerance in patients with pulmonary hypertension. Two groups of patients were studied. One group consisted of 37 patients with normal pulmonary artery pressure who underwent surgical closure of a left-to-right shunt. Another group was composed of 10 patients with pulmonary hypertension. Both patient groups were compared with the mean value of an age-matched pool of normal control subjects. Aerobic exercise performance was assessed by determination of the ventilatory threshold. The ventilatory efficiency for CO2 was assessed by calculating the slope of ventilation over carbon dioxide below the ventilatory threshold. The slope of ventilation vs. carbon dioxide output in patients with pulmonary hypertension (48 +/- 12) was steeper than the slope (31.3 +/- 7.0) in patients with normal pulmonary artery pressure (P < 0.05). Significant correlations (P < 0.05) were found between the pulmonary artery pressure and the slope of pulmonary ventilation over carbon dioxide (r = 0.92) and also with the physiological dead space-tidal volume ratio at maximal exercise (r = 0.55). This was associated with a severe reduction in exercise performance in patients with pulmonary hypertension, whereas in patients with normal pulmonary artery pressure it was only slightly below the lower limit of normal. These results demonstrate that patients with pulmonary hypertension have an inefficient ventilatory response to metabolically produced CO2 during exercise, which severely limits exercise tolerance.
本研究的目的是分析肺动脉高压患者运动耐量评估中二氧化碳（CO₂）通气效率。研究了两组患者。一组由37例接受左向右分流手术闭合的肺动脉压力正常患者组成。另一组由10例肺动脉高压患者组成。将两组患者与年龄匹配的正常对照受试者池的平均值进行比较。通过测定通气阈值评估有氧运动表现。通过计算通气阈值以下通气量与二氧化碳量的斜率评估CO₂通气效率。肺动脉高压患者通气量与二氧化碳排出量的斜率（48±12）比肺动脉压力正常患者的斜率（31.3±7.0）更陡（P<0.05）。肺动脉压力与通气量与二氧化碳的斜率（r = 0.92）以及最大运动时的生理死腔潮气量比（r = 0.55）之间存在显著相关性（P<0.05）。这与肺动脉高压患者运动表现严重降低相关，而肺动脉压力正常患者仅略低于正常下限。这些结果表明，肺动脉高压患者在运动期间对代谢产生的CO₂通气反应效率低下，这严重限制了运动耐量。
