Sugawara J, Tanabe T, Miyachi M, Yamamoto K, Takahashi K, Iemitsu M, Otsuki T, Homma S, Maeda S, Ajisaka R, Matsuda M
Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Namiki, Tsukuba, Ibaraki, Japan.
Acta Physiol Scand. 2003 Dec;179(4):361-6. doi: 10.1046/j.0001-6772.2003.01211.x.
The Modelflow method can estimate cardiac output from arterial blood pressure waveforms using a three-element model of aortic input impedance (aortic characteristic impedance, arterial compliance, and systemic vascular resistance). We tested the reliability of a non-invasive cardiac output estimation during submaximal exercise using the Modelflow method from finger arterial pressure waveforms collected by Portapres in healthy young humans.
The Doppler echocardiography method was used as a reference method. Sixteen healthy young subjects (nine males and seven females) performed a multi-stage cycle ergometer exercise at an intensity corresponding to 70, 90, 110 and 130% of their individual ventilatory threshold for 2 min each. The simultaneous estimation of cardiac output (15 s averaged data) using the Modelflow and Doppler echocardiography methods was performed at rest and during exercise.
The Modelflow-estimated cardiac output correlated significantly with the simultaneous estimates by the Doppler method in all subjects (r = 0.87, P < 0.0001) and the SE of estimation was 1.93 L min-1. Correlation coefficients in each subject ranged from 0.91 to 0.98. Although the Modelflow method overestimated cardiac output, the errors between two estimates were not significantly different among the exercise levels. These results suggest that the Modelflow method using Portapres could provide a reliable estimation of the relative change in cardiac output non-invasively and continuously during submaximal exercise in healthy young humans, at least in terms of the relative changes in cardiac output.
Modelflow方法可使用主动脉输入阻抗的三元件模型（主动脉特性阻抗、动脉顺应性和全身血管阻力）从动脉血压波形估计心输出量。我们使用Modelflow方法，通过Portapres收集的手指动脉压力波形，测试了健康年轻人在次最大运动期间无创心输出量估计的可靠性。
采用多普勒超声心动图方法作为参考方法。16名健康年轻受试者（9名男性和7名女性）进行多级自行车测力计运动，强度分别对应于其个体通气阈值的70%、90%、110%和130%，每次运动2分钟。在静息和运动期间，使用Modelflow和多普勒超声心动图方法同时估计心输出量（15秒平均数据）。
在所有受试者中，Modelflow估计的心输出量与多普勒方法同时估计的值显著相关（r = 0.87，P < 0.0001），估计标准误为1.93 L min-1。每个受试者的相关系数范围为0.91至0.98。尽管Modelflow方法高估了心输出量，但两种估计之间的误差在不同运动水平之间没有显著差异。这些结果表明，使用Portapres的Modelflow方法可以在健康年轻人类次最大运动期间无创且连续地可靠估计心输出量的相对变化，至少在心输出量的相对变化方面是如此。
