Heart-rate telemetry for evaluation of the energy expenditure of children with cerebral palsy

Abstract

Heart-rate monitoring with telemetric equipment was performed on 10 youngsters with cerebral palsy during their usual activities. Oxygen uptake was determined from gas analysis of expired air on a total of 50 occasions on four subjects (study A) to calibrate the heart rate to energy expenditure. Six other subjects participated only in one or two oxygen uptake determinations each (study B). Individual regression analysis of the oxygen uptake and the corresponding heart rate was performed in study A. The mean daily oxygen uptake could then be calculated from the regression line and the mean daily heart rate found during monitoring. A crossover point of the four regression lines and of a common line of all data in studies A and B was found at a heart rate of approximately 75 beats/min and oxygen uptake of 11.5 ml x min^–1(kg BCM)^–1. This point was called basal and was used in a simplified study. In this study, the regression lines were replaced by a line connecting the basal point with the mean of the first two determinations performed in study A, and with the one observation or the mean of two observations performed on each subject in study B. The mean daily oxygen uptake was read from these lines. The two ways of calculating the energy expenditure were compared with one another for study A subjects. Two subjects showed identical results, but the other two differed by 20%. The energy expenditures of all subjects were also compared with their energy intake (dietary records) and to their body fat mass (isotope dilution methods). The calculated energy expenditure then appeared to be generally sensible.