Baroreflex sensitivity and body growth parameters in children and adolescents

To determine the difference between baroreflex sensitivity expressed in ms/mmHg (BRS) and in Hz/mmHg (BRSf) in relation to body growth parameters.

Two hundred one children and adolescents aged 10 to 21 years (mean age +/- SD 14.7+/-3.1 years) were examined. This population was analyzed as a whole and subsequently was divided into two groups: group A consisted of normotensive, healthy control subjects (n=154); and group B consisted of children with systolic casual blood pressure on primary diagnosis greater than 140 mmHg, measured three times at least one week apart (n=47). These groups were divided into subgroups according to age. BRS and BRSf were determined by spectral analysis of blood pressure and pulse interval variability (5 min records by Finapres, metronome-controlled breathing at a frequency of 0.33 Hz). Body growth parameters (body height, weight and body mass index [BMI]) were assessed. The Spearman correlation coefficient was calculated between pairs of all parameters (age, pulse interval, BRS, BRSf, height, weight, BMI) for the whole group, for groups A and B, and for age-related subgroups.

BRS did not correlate with age; it correlated with pulse interval in the whole population, in groups A and B, and in age-related subgroups. BRS correlated significantly only with weight, height or BMI in the oldest group (age 17 to 19 years), but there was no correlation with groups A or B, or with the whole study population. BRSf correlated significantly (P<0.01) with age, and was pulse interval independent in group A and the age-related subgroups. BRSf correlated with weight, height and BMI in group A and in the whole population, but not in the age-related subgroups.

BRS (a mean pulse interval-related parameter) does not correlate with age. On the contrary, BRSf (which is mean pulse interval independent) decreases significantly with age. The significant relation between BRSf and parameters of body growth is related to age.