Reneaux C, Desplan J
Service de Physiopathologie Respiratoire et Cérébrale, Hôpital Saint Jacques, Besançon.
Rev Pneumol Clin. 1997;53(5):271-7.
The different parameters used in cardiopneumologic exercise tests allow an assessment of exercise tolerance on the basis of the subject's ventilatory response, cardiac and metabolic adaptation and gas exchanges during exercise. VO2max and dyspnea are indicators of good or poor exercise tolerance. Normal values established for adults in three reference articles depend on age, body weight and height. In a 20-year-old non sedentary subject, VO2max is approximately 45 ml/mn/kg and decreases to 25 ml/mn/kg at 65 years of age. Dyspnea is measured on two types of scales, categorical and visual analogue scales. "Minimal dyspnea" at maximal effort is normal in a healthy subject but becomes "very severe" in diseased subjects. A dyspnea threshold can be determined from the evolution of dyspnea during the test and is useful for retraining in patients with chronic obstructive lung disease. The normal ventilatory response always leaves a ventilatory reserve equal to 30% of the theoretical maximal ventilatory output. If the reserve is diminished, exercise is limited by ventilatory capacity. Gas exchanges reflect muscle adaptation to exercise and the homogeneous nature of alveolar ventilation compared with pulmonary perfusion (VA/Q). This depends on the physiological dead space (VD/VT) which is approximately 1/3 at rest decreasing to 1/4 or 1/5 at maximal exercise. VD/VT is high at rest and stays high during exercise in interstitial lung disease and vascular lung disease. VA/Q also depends on the alveo-arterial oxygen differential (P(A-a)O2) which increases two-fold during exercise. Expired gas and arterial gas must be measured simultaneously for the calculation. To measure cardiac adaptation, the ECG, heart rate and oxygen pulse (VO2/HR) must be recorded. The kinetics of oxygen pulse is more important than its maximal value, a decrease with unchanged heart rate suggests early-stage cardiomyopathy. Finally, blood lactate, the metabolic response to exercise, is used to determine the lactate threshold or the anaerobic threshold. Measurement of the ventilatory threshold is less invasive, ventilatory outflow increasing with increasing lactate level as described by the Beaver or Wassermann model. These thresholds indicate the subject's aerobic capacity. The exercise test has diagnostic value but can also be useful for individual patient management, particularly cardiorespiratory rehabilitation.
心肺运动试验中使用的不同参数可根据受试者的通气反应、心脏和代谢适应情况以及运动期间的气体交换来评估运动耐力。最大摄氧量（VO2max）和呼吸困难是运动耐力良好或不佳的指标。三篇参考文献中为成年人确定的正常值取决于年龄、体重和身高。在一名20岁的非久坐受试者中，VO2max约为45毫升/分钟/千克，在65岁时降至25毫升/分钟/千克。呼吸困难通过两种量表进行测量，即分类量表和视觉模拟量表。在健康受试者中，最大努力时的“轻微呼吸困难”是正常的，但在患病受试者中会变为“非常严重”。可以根据测试期间呼吸困难的变化来确定呼吸困难阈值，这对慢性阻塞性肺疾病患者的再训练很有用。正常的通气反应总是会留下相当于理论最大通气输出量30%的通气储备。如果储备减少，运动就会受到通气能力的限制。气体交换反映了肌肉对运动的适应情况以及与肺灌注（VA/Q）相比肺泡通气的均匀性。这取决于生理死腔（VD/VT），其在静息时约为1/3，在最大运动时降至1/4或1/5。在间质性肺疾病和血管性肺疾病中，VD/VT在静息时较高，在运动期间也保持较高水平。VA/Q还取决于肺泡 - 动脉氧分压差（P(A-a)O2），其在运动期间会增加两倍。为了进行计算，必须同时测量呼出气体和动脉气体。为了测量心脏适应情况，必须记录心电图、心率和氧脉搏（VO2/HR）。氧脉搏的动力学比其最大值更重要，心率不变时氧脉搏下降提示早期心肌病。最后，血液乳酸，即对运动的代谢反应，用于确定乳酸阈值或无氧阈值。通气阈值的测量侵入性较小，通气输出量会随着乳酸水平的升高而增加，如比弗（Beaver）或瓦瑟曼（Wassermann）模型所述。这些阈值表明受试者的有氧能力。运动试验具有诊断价值，但对个体患者的管理也很有用，特别是在心肺康复方面。
