Centro Cardiologico Monzino, IRCCS, Italy.
Department of Clinical Sciences and Community Health, Università degli Studi di Milano, Italy.
Eur J Prev Cardiol. 2019 Oct;26(15):1616-1622. doi: 10.1177/2047487319845967. Epub 2019 Apr 25.
Inert gas rebreathing has been recently described as an emergent reliable non-invasive method for cardiac output determination during exercise, allowing a relevant improvement of cardiopulmonary exercise test clinical relevance. For cardiac output measurements by inert gas rebreathing, specific respiratory manoeuvres are needed which might affect pivotal cardiopulmonary exercise test parameters, such as exercise tolerance, oxygen uptake and ventilation vs carbon dioxide output (VE/VCO) relationship slope.
We retrospectively analysed cardiopulmonary exercise testing of 181 heart failure patients who underwent both cardiopulmonary exercise testing and cardiopulmonary exercise test+cardiac output within two months (average 16 ± 15 days). All patients were in stable clinical conditions (New York Heart Association I-III) and on optimal medical therapy.
The majority of patients were in New York Heart Association Class I and II (78.8%), with a mean left ventricular ejection fraction of 31 ± 10%. No difference was found between the two tests in oxygen uptake at peak exercise (1101 (interquartile range 870-1418) ml/min at cardiopulmonary exercise test vs 1103 (844-1389) at cardiopulmonary exercise test-cardiac output) and at anaerobic threshold. However, anaerobic threshold and peak heart rate, peak workload (75 (58-101) watts and 64 (42-90), < 0.01) and carbon dioxide output were significantly higher at cardiopulmonary exercise testing than at cardiopulmonary exercise test+cardiac output, whereas VE/VCO slope was higher at cardiopulmonary exercise test+cardiac output (30 (27-35) vs 33 (28-37), < 0.01).
The similar anaerobic threshold and peak oxygen uptake in the two tests with a lower peak workload and higher VE/VCO slope at cardiopulmonary exercise test+cardiac output suggest a higher respiratory work and consequent demand for respiratory muscle blood flow secondary to the ventilatory manoeuvres. Accordingly, VE/VCO slope and peak workload must be evaluated with caution during cardiopulmonary exercise test+cardiac output.
最近有研究描述了一种新的可靠的非侵入性方法，即在运动期间通过惰性气体再呼吸来确定心输出量，这使得心肺运动测试的临床相关性得到了显著改善。在通过惰性气体再呼吸进行心输出量测量时，需要特定的呼吸动作，这可能会影响心肺运动测试的关键参数，例如运动耐量、摄氧量和通气与二氧化碳输出（VE/VCO）关系斜率。
我们回顾性分析了 181 例心力衰竭患者的心肺运动测试数据，这些患者在两个月内（平均 16±15 天）同时进行了心肺运动测试和心肺运动测试+心输出量测试。所有患者均处于稳定的临床状态（纽约心脏协会 I-III 级），并接受最佳药物治疗。
大多数患者处于纽约心脏协会 I 级和 II 级（78.8%），平均左心室射血分数为 31±10%。两种测试在心输出量峰值时的摄氧量（心肺运动测试中为 1101（四分位间距 870-1418）ml/min，心肺运动测试+心输出量中为 1103（844-1389）ml/min）和无氧阈时无差异。然而，无氧阈和峰值心率、峰值工作量（75（58-101）瓦特和 64（42-90）， < 0.01）和二氧化碳输出在心肺运动测试中显著高于心肺运动测试+心输出量，而 VE/VCO 斜率在心肺运动测试+心输出量中更高（30（27-35）比 33（28-37）， < 0.01）。
两种测试的无氧阈和峰值摄氧量相似，但心肺运动测试+心输出量的峰值工作量较低，VE/VCO 斜率较高，提示呼吸功较高，继而导致呼吸肌血流需求增加，这可能是由于通气动作所致。因此，在进行心肺运动测试+心输出量时，必须谨慎评估 VE/VCO 斜率和峰值工作量。
