[Continuous ambulatory measurement of blood pressure in children--personal experience]

Ambulatory blood pressure monitoring (ABPM) during normal daily activities and during night, when the patient is asleep, is a new method of measuring blood pressure (BP) in children, used for better diagnosis and treatment of hypertension. Compared to casual BP measurements, it documents normal daily BP variations, BP during sleep, the influence of emotional and physical stress on BP and is a better predictor of hypertension associated with end-organ damage. However, the experience in ABPM in children is still limited. In our country ABPM has been used since recently, and first results are referred to children with end-stage renal failure.

ABPM was performed in two groups of children: group A consisted of 61 children, aged 14.3 +/- 2.9 (mean +/- SD) yrs in whom intermittent outpatient BP measurements (for at least 3 months) suggested the diagnosis of hypertension (according to the data of Second Task Force); group B consisted of 52 patients (pts), aged 12.8 +/- 4.6 yr with renal disease. Four pts from group A (6.6%) and 20 pts from group B (38.5%) received antihypertensive therapy (captopril, nifedipine, furosemide and propranolol ). All children from group A and half of the children from group B had normal renal function. Eighteen pts from group B were on chronic haemodialysis (34.6%). Blood pressure was recorded during a 24-hour period except in haemodialyzed pts (48 h) (Table 1). Results of BP measurements are presented as the mean values of BP during a 24-hour period, during normal daily activities and during sleep. We used the age- and gender-appropriate 95th percentile from the Task Force Study as the daytime upper-limit of normal and 10% lower for the upper-limit at night. According to BP load (the percentage of BPs exceeding the upper limits of normal for age), children were assumed to have mild-to-moderate hypertension (BP load between 20% and 40%) or severe hypertension (BP load more than 40%). The success of antihypertensive therapy was evaluated after 1-3 months in 11 pts (twice in 10 pts and three times in one pt).

In group A 39.4% of pts were normotensive and 36.1% were without antihypertensive therapy, 58.4% of normotensive and 40.5% of hypertensive pts had blunted circadian BP rhythm (nocturnal BP reduction of less than 10% of diurnal values) (Graph. 1). In group B 38.5% of pts were normotensive and 27% were without antihypertensive therapy. In the group of normotensive pts alteration of circadian BP rhythm was found in 40% of pts with normal renal function, 80% of pts with chronic renal failure and in 100% of pts with terminal renal failure, while in the hypertensive group, altered circadian BP rhythm had 68%, 100% and 92% of pts, respectively (Graph 2). Mild-to-moderate hypertension had 54% of hypertensive pts from group A and 37.5% of hypertensive pts from group B. Severe hypertension was more frequent in group B (62.5%) comparing to group A (46%). The effectiveness of antihypertensive therapy was assessed in 11 pts. In 69.2% of pts BP became normal or was significantly decreased, in 23.1% of pts BP was not changed and 7.7% of pts had higher values of BP.

ABPM is very useful for diagnosing white coat hypertension. Like other authors, we have pointed out that more than one third of pts who were hypertensive according to usual BP measurements had normal 24-hour BP and we classified them as white coat hypertensives. More than a half of the pts had blunted circadian BP rhythm, and as it is not certain whether they will become hypertensive in adulthood they should be periodically controlled. There are several proofs that results of ABPM have a better correlation with hypertensive end-organ damage; therefore ABPM is used for assessing the severity of hypertension. In our former work, we showed excellent correlation of BP with left ventricular mass index in children with end-stage renal failure. (ABSTRACT TRUNCATED)