Kim D W, Song C G, Lee M H
Department of Medical Engineering, Yonsei University, Seoul, Korea.
Front Med Biol Eng. 1992;4(3):179-88.
In this study, a new ensemble average technique is developed to measure cardiac output during treadmill exercise. Each dz/dt peak is used as a starting point for ensemble averaging, instead of the conventionally used R point of the ECG, in order to prevent the peak dz/dt waveform (C point) from smoothing, which results in increased dz/dtmax. The R-Z interval from the R point of the ECG to the peak dz/dt varies for each heart beat especially during strenuous exercise. Signal-to-noise ratios of five subjects obtained with the new technique are 0-32.6% higher than those obtained with the conventional technique at rest and during four levels of treadmill exercise. Power spectral densities of the averaged dz/dt waveforms by the peak dz/dt and R point references are also analyzed. Stroke volumes of the five subjects averaged by the peak dz/dt are 0-23.5% higher than those obtained by the R point at rest and during four levels of exercise.
在本研究中，开发了一种新的总体平均技术来测量跑步机运动期间的心输出量。为防止dz/dt峰值波形（C点）平滑，从而导致dz/dtmax增加，每个dz/dt峰值被用作总体平均的起点，而不是传统上使用的心电图R点。从心电图R点到dz/dt峰值的R-Z间期在每次心跳时都会变化，尤其是在剧烈运动期间。五名受试者采用新技术获得的信噪比在静息状态和跑步机运动四个水平期间比采用传统技术获得的信噪比高0-32.6%。还分析了通过dz/dt峰值和R点参考得到的平均dz/dt波形的功率谱密度。五名受试者通过dz/dt峰值平均得到的每搏输出量在静息状态和四个运动水平期间比通过R点得到的每搏输出量高0-23.5%。
