Autonomic nervous system function in infants and adolescents: impact of autonomic tests on heart rate variability.

Measurement of heart rate variability (HRV) shows information on the functional state of the autonomic nervous system (ANS). In adults there are standardized autonomic tests and well-established ranges of normal values, which is not the case in children. The aim of the present study was (1) to introduce an ANS test battery, especially for children and adolescents; (2) to establish normative HRV parameters; and (3) to determine the impact of ANS tests on HRV parameters compared with baseline measurements. We investigated 100 healthy children and adolescents between 6 and 15 years old. We subdivided the investigated group into a group of children (5-11 years old) and adolescents (12-15 years old) and measured HRV by time and frequency domain parameters during baseline, rhythmic breathing, Valsalva test, active standing, tilt-table testing, and handgrip test. The normative HRV data are presented by means, SDs, medians, and percentiles. The results described refer to baseline values for each HRV parameter separately to demonstrate the influence of age on HRV parameters. The study results present not only first normative HRV data for an autonomic test battery especially adapted to children and adolescents, but they also quantify the autonomic changes induced by test procedures compared with baseline measurements.