CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 3, 1998, No 1

Oxygen Uptake Kinetics During P.R.B.S. Exercise in Children

M. Massin, B. Derkenne, J. Leclercq-Foucart, J.-P. Sacré, J.-M. Chantraine

Abstract:
Background: The pseudorandom binary sequence (PRBS)-technique is a useful tool for investigating the dynamic response of oxygen uptake within the aerobic range. However the validity of this kind of multifrequent testing has never been controlled in children. Methods: PRBS exercise was completed by 50 healthy children and by 30 cardiac children, 15 being in NYHA functional class 1 und 15 in class 2. The basic steps of the approach were: (1) measure the breath-by-breath oxygen uptake, carbon dioxide output and ventilation response, and the heart rate response to a multifrequent input signal, (2) compute the autocorrelation function (ACF) of the input signal and the crosscorrelation function (CCF) between input and responses of examined data (lag time and peak value of the correlations), (3) compute the Fourier transforms of both functions to obtain their spectral densities and (4) compute the frequency response from those spectral densities (amplitude ratios and phase shifts). Results: The ACF results in a correlation of 1 at times equivalent to a multiple of the PRBS period. The CCF lags behind and reaches a lower peak value for each datum. The amplitude ratios decrease and the phase shifts increase with increasing frequency. The lag time is longer, the peak value and the amplitude ratios are lower in all cardiac children for the oxygen uptake and in cardiac children in class II for the other data. Conclusion: PRBS exercise seems to be a very sensitive method of assessing the performance capacity in children.

Keywords:
gas exchange kinetics, PRBS, breath-by-breath analysis, spectral analysis, heart rate kinetics

Address for Correspondence:

Reference:
(CVE. 1998; 3 (1): 16-21)

[Pabst Science Publishers] [CVE Homepage] [Contents] [Editorials] [Masthead] [Search] [Orders]

PABST SCIENCE PUBLISHERS
Lengerich, Berlin, Düsseldorf,
Leipzig, Riga, Scottsdale AZ (USA),
Wien, Zagreb