[Ambulatory arterial blood pressure in normotensive children]

The aim of the present study was to obtain out patient blood pressure values in normotensive children based on age, height, and sex in order to determine reference values.

Out patient blood pressure monitorization was performed in 248 healthy normotensive children (129 males and 119 females, ages 6 to 16 years) (casual blood pressure < P95 specific for age and sex) over 24 hours by the Spacelabs 90207 oscilometric monitor on a normal schoolday. An appropriately sized armband was chosen for each case with the readings being programmed every 20 minutes between 6:00 a.m. and midnight and every 30 minutes for the remaining readings. The means of 24 hour blood pressure (all the readings obtained), day period (8 to 22 hours) and night period (midnight to 6:00 a.m.) and the circadian variability (difference and the ratio between the mean values of day and night) were calculated. The children were divided into subgroups according to sex, age (6-9, 10-12 and 13-16 years) and height (1.09-1.37; 1.38-1.51, and 1.52-1.75 meters). Monitorizations with a percentage of erroneous readings over 30% were excluded from the study.

Only 7 children were excluded due to a high percentage of erroneous readings. The mean of the valid readings made in the remaining 241 cases was 62 +/- 7. A significant increase was observed in the values of out patients systolic blood pressure with age and height. The same was not seen in diastolic blood pressure. Nocturnal blood pressures were lower to the diurnal pressures (11% systolic, 22% diastolic). P95 was considered as the upper limit of normality for the means of each of the periods of systolic and diastolic blood pressure in each subgroup of sex, age and height.

The blood pressure values obtained from a population of normotensive children may be useful to understand the behaviour of out patient blood pressure in children and establish the limit for defining high blood pressure.