McKelvie R S, Heigenhauser G J, Jones N L
Ambrose Cardiorespiratory Unit, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
Chest. 1987 Nov;92(5):777-82. doi: 10.1378/chest.92.5.777.
The ability to determine cardiac output (Q) noninvasively during a nonsteady state (NSS) incremental exercise test was assessed. Seven healthy subjects performed two maximal incremental cycle ergometer exercise tests (100 kpm/min increments every minute), and also steady state exercise (SS) at 25, 50, and 75 percent of their maximum power output. The Q was determined by the indirect CO2 Fick method; mixed venous PCO2 was calculated using the exponential CO2 rebreathing method. No significant differences were observed for the cardiac output/oxygen uptake relationship (Q/VO2) obtained between the two incremental exercise tests. During NSS, the Q/VO2 was linear (r = .89; intercept = 5.69 L/min; slope = 5.39). During the SS, Q/VO2 was linear (r = .90; intercept = 5.47 L/min; slope = 4.87). No significant difference was observed between the SS and NSS Q/VO2 relationships (p greater than 0.05), and the NSS relationship was similar to Q/VO2 values previously reported in the literature. Accurate and reproducible measurements of Q can be obtained noninvasively in healthy subjects using the exponential CO2 rebreathing method during incremental progressive exercise tests, with similar values at comparable VO2 to those obtained in the steady state.
评估了在非稳态（NSS）递增运动试验期间无创测定心输出量（Q）的能力。七名健康受试者进行了两次最大递增式自行车测力计运动试验（每分钟递增100 kpm/min），并在其最大功率输出的25%、50%和75%进行了稳态运动（SS）。通过间接二氧化碳菲克法测定Q；使用指数二氧化碳再呼吸法计算混合静脉血PCO2。两次递增运动试验之间获得的心输出量/摄氧量关系（Q/VO2）未观察到显著差异。在NSS期间，Q/VO2呈线性（r = 0.89；截距 = 5.69 L/min；斜率 = 5.39）。在SS期间，Q/VO2呈线性（r = 0.90；截距 = 5.47 L/min；斜率 = 4.87）。SS和NSS的Q/VO2关系之间未观察到显著差异（p大于0.05），且NSS关系与文献中先前报道的Q/VO2值相似。在递增渐进运动试验期间，使用指数二氧化碳再呼吸法可在健康受试者中无创获得准确且可重复的Q测量值，在可比的VO2下其值与稳态时获得的值相似。
