Abstract
Autonomic nerve functions were evaluated based on variations in the R-R interval in the electrocardiographs of 1, 261 healthy subjects from 5 to 79 years of age, and the normal reference ranges and standard prediction equations were derived. R-R intervals were recorded at rest, during deep breathing, during Valsalva manoeuvre, and on standing, and their mean, standard deviation (SD), coefficient of variation (CV), and the ratio of maximal to minimal value (MAX/MIN) were calculated. Age, but not sex, was significantly correlated with the parameters of autonomic nerve function. Therefore normal reference ranges obtained by a parametric method were subdivided into 8 levels by age in decades. SD, CV, and MAX/MIN of 100 R-R intervals at rest and during deep breathing significantly decreased (p<0.01) with aging. Moreover, the multiple correlation coefficient of autonomic nerve functions with the biological characteristic factors (sex, age, body weight, and height) were calculated, and standard prediction equations of high reliability (p<0.01) were obtained by multivariate analysis of the autonomic nerve functions.
