Clark A L, Volterrani M, Swan J W, Coats A J
Department of Cardiac Medicine, National Heart and Lung Institute, London, UK.
Int J Cardiol. 1995 Mar 3;48(3):259-70. doi: 10.1016/0167-5273(94)02267-m.
The exercise limitation of patients with chronic heart failure is associated with an increased ventilatory response during exercise. This is thought to be due, at least in part, to excessive dead space ventilation.
To assess ventilation perfusion matching, 20 patients with chronic heart failure and eight controls with asymptomatic left ventricular dysfunction underwent symptom limited treadmill exercise with arterial blood sampling. Metabolic gas exchange was determined by expired gas analysis. Fractional dead space ventilation and the alveolar arterial oxygen difference were derived.
There was a fall in fractional dead space ventilation (0.43 to 0.28; P < 0.001), more marked in the controls (peak dead space fraction 0.19 (controls), 0.32 (patients); P = 0.002). There was a rise in alveolar arterial difference in all patients (1.59 to 2.55 kPa; P = 0.006) with no difference between patients and controls. Arterial carbon dioxide tension fell during exercise (4.89 to 4.63 kPa; P < 0.001), with no difference between patients and controls. There was no significant change in arterial oxygen tension.
The fall in arterial carbon dioxide was the same in both patients and controls. The modest increase in alveolar-arterial oxygen difference tension was the same in both groups, which, coupled with the stable arterial oxygen tension makes it unlikely that a primary change in ventilation-perfusion matching is the cause of increased ventilatory response to exercise in chronic heart failure.
慢性心力衰竭患者的运动耐力受限与运动期间通气反应增加有关。这至少部分被认为是由于无效腔通气过多。
为评估通气-灌注匹配情况，20例慢性心力衰竭患者和8例无症状左心室功能障碍的对照者进行了症状限制性平板运动试验并采集动脉血样。通过呼出气分析测定代谢性气体交换。计算无效腔通气分数和肺泡-动脉血氧分压差。
无效腔通气分数下降（从0.43降至0.28；P<0.001），在对照组中更明显（峰值无效腔分数：对照组为0.19，患者组为0.32；P = 0.002）。所有患者的肺泡-动脉血氧分压差均升高（从1.59 kPa升至2.55 kPa；P = 0.006），患者与对照组之间无差异。运动期间动脉二氧化碳分压下降（从4.89 kPa降至4.63 kPa；P<0.001），患者与对照组之间无差异。动脉血氧分压无显著变化。
患者和对照组的动脉二氧化碳下降情况相同。两组的肺泡-动脉血氧分压差均适度增加，再加上动脉血氧分压稳定，这使得通气-灌注匹配的原发性改变不太可能是慢性心力衰竭患者运动通气反应增加的原因。
