Ambulatory blood pressure monitoring in the pediatric patient

White coat hypertension in pediatrics

The article summarizes current information on blood pressure changes in children during clinic visit. White coat as a general dressing of physicians and health care personnel has been widely accepted at the end of the 19th century. Two problems can be associated with the use of white coat: white coat phenomenon and white coat hypertension. Children often attribute pain and other unpleasant experience to the white coat and refuse afterwards cooperation with examinations. Definition of white coat hypertension in the literature is not uniform. It has been defined as elevated blood pressure in the hospital or clinic with normal blood pressure at home measured during the day by ambulatory blood pressure monitoring system. White coat effect is defined as temporary increase in blood pressure before and during visit in the clinic, regardless what the average daily ambulatory blood pressure values are. Clinical importance of white coat hypertension is mainly because of higher risk for cardiovascular accidents that are dependent on end organ damage (heart, vessels, kidney). Current data do not allow any clear recommendations for the treatment. Pharmacological therapy is usually started in the presence of hypertrophic left ventricle, changes in intimal/medial wall thickness of carotic arteries, microalbuminuria and other cardiovascular risk factors. Nonpharmacological therapy is less controversial and certainly more appropriate. Patients have to change their life style, need to eliminate as much cardiovascular risk factors as possible and sustain a regular blood pressure monitoring.

Obstructive sleep apnea and periodic limb movement disorder in a population of children with hypertension and/or nocturnal nondipping blood pressures

There is a reported association between hypertension (HTN) and sleep disorders. The American Academy of Pediatrics recommends screening children with HTN for sleep disorders because sleep disorders increase the risk for cardiovascular disease. We quantified the frequency and severity of sleep disorders within our institution's hypertensive pediatric population and evaluated the effectiveness of performing nocturnal polysomnography (NPSG). In the hypertensive pediatric population referred for NPSG at our institution, 64% were diagnosed with obstructive sleep apnea (OSA) and/or periodic limb movement disorder. Thirty-three percent of those children with HTN had moderate to severe OSA, whereas only 20% of all children evaluated by NPSG had moderate to severe OSA. Those children with HTN were also two times more likely to be diagnosed with periodic limb movement disorder. Screening for sleep disorders and obtaining NPSG in children with HTN increase the identification of comorbid sleep disorders and reduce the risk for cardiovascular disease.

Ambulatory and home blood pressure monitoring in children and adolescents: diagnosis of hypertension and assessment of target-organ damage

The prevalence of elevated blood pressure in children and adolescents is more common than previously believed and often represents the early onset of essential hypertension, particularly in adolescents. The definition of hypertension in children is based on distribution criteria and normalcy tables that provide blood pressure percentiles for each measurement method (office, ambulatory and home) according to the individual's age, gender and body size. Owing to the white coat and masked hypertension phenomena, ambulatory blood pressure monitoring is indispensable for the diagnosis of hypertension in children. Home blood pressure monitoring in children has been less well studied, and at present, treatment decisions should not be based solely on such measurements. Hypertension-induced preclinical target-organ damage (mainly echocardiographic left ventricular hypertrophy) is not uncommon in children and should be evaluated in all hypertensive children. Other indices of target-organ damage, such as carotid intima-media thickness, pulse wave velocity and microalbuminuria, remain under investigation in pediatric hypertension.

Hypertension in children and adolescents

Pediatric hypertension (HTN) has become the focus of interest recently due to its increasing prevalence. This is mainly related to the increase in childhood obesity, although the current evidence suggests that other lifestyle factors, apart from obesity, contribute to high blood pressure (BP) in childhood. Traditionally, office BP measurements by the physician have been the cornerstone for the assessment of HTN in children. However, since the white coat and masked HTN phenomena are not rare in childhood, out-of-office BP measurements have significantly improved the accurate diagnosis of HTN and decision making. Ambulatory BP monitoring is regarded as indispensable for the evaluation of pediatric HTN, providing details not only for the staging for HTN, but also for the study of other ambulatory BP patterns. It should be pointed out that HTN in children and adolescents is associated with target-organ damage which is significant in terms of cardiovascular risk. The current knowledge, outlined in the present review, is expected to help in early and accurate diagnosis as well as in the management of HTN in children and adolescents.

Ambulatory blood pressure monitoring in children: imperfect yet essential

There has been increasing emphasis on hypertension and early cardiovascular disease in the pediatric age group over the past decade as a result of various factors, including the obesity epidemic and publication of new clinical guidelines. A key component of identifying children and adolescents with definite or potential hypertension is proper blood pressure (BP) measurement. While ambulatory blood pressure monitoring (ABPM) offers the potential for improved detection of youths at increased cardiovascular risk, it has not been widely adopted. This commentary highlights the crucial role of ABPM in the context of current trends, while at the same time identifying the current barriers to more widespread application of this technique. Chief among these is the lack of a robust, universally applicable database of pediatric ABPM normative values. Even in the absence of ideal normative data, ABPM can and should be widely applied, and a potential algorithm for such an approach is presented.

Office, ambulatory and home blood pressure measurement in children and adolescents

There is an increasing interest in pediatric hypertension, the prevalence of which is rising in parallel with the obesity epidemic. Traditionally the assessment of hypertension in children has relied on office blood pressure (BP) measurements by the physician. However, as in adults, office BP might be misleading in children mainly due to the white coat and masked hypertension phenomena. Thus, out-of-office BP assessment, using ambulatory or home monitoring, has gained ground for the accurate diagnosis of hypertension and decision-making. Ambulatory monitoring is regarded as indispensable for the evaluation of pediatric hypertension. Preliminary data support the usefulness of home monitoring, yet more evidence is needed. Office, ambulatory and home BP normalcy tables providing thresholds for diagnosis have been published and should be used for the assessment of elevated BP in children.

Primary hypertension at a single center: treatment, time to control, and extended follow-up

We present data on presentation, treatment, and follow-up of 65 pediatric patients with primary hypertension treated over the past 12 years, including initial anthropometric data, pharmacologic treatment, time to control for both systolic and diastolic blood pressure (SBP/DBP), and maintenance of control over time. Data was normalized to standard deviation scores (SDS) for mathematical analysis, and antihypertensive medication dosages were converted to dosage equivalents for a single member of each antihypertensive class. We used multiple regression analysis and Kaplan- Meier survival curves to determine the time to control, medication, and dose effectiveness. Patients were seen for an average of seven visits over 25 months. Initial BPs averaged 134/71 mmHg (2.1/0.6 SDS). Patients were taller, heavier, and had higher body mass index than average for age and sex. By the fourth visit, SBP was <90th percentile in 79%. Ninety percent could be controlled, although 32 lost control at some point (at least 16 due to noncompliance). At the last visit, 46 were controlled, and 5/8 patients off medication remained normotensive. Only angiotensin-converting enzyme inhibitors and beta-blockers demonstrated significant association with BP control. This is the first study to document the time to control of BP, and it can serve as an initial standard for quality assessment.

Blood pressure load, proteinuria and renal function in pre-hypertensive children

It is as yet unclear whether blood pressure load (BPL) can affect renal function in pre-hypertensive children. We have studied 250 children, with a mean age of 9.12 +/- 3.28 years, with the aim of assessing if pre-hypertension in children can indeed affect renal function. The study cohort consisted of 146 children with pre-hypertension (group P) and a control group of 104 children with normal blood pressure (group C). All children were tested for orthostatic proteinuria, an exclusion criterion, glomerular filtration rate (GFR), and proteinuria, and ambulatory blood pressure monitoring was performed. Based on the BPL, group P was further subdivided into group P1 (BPL <or= 40%, low BPL) and group P2 (BPL > 40%, high BPL). We found that GFR was reduced in pre-hypertensive children (90.74 +/- 48.69 vs. 110.32 +/- 20.30 ml/min per 1.73 m(2), p < 0.0001) and that proteinuria was increased (145.36 +/- 110.91 vs. 66.84 +/- 42.94 mg/m(2) per 24 h; p < 0.0001). However, mean values were still within normal limits. A comparison of the group with high BPL and that with low BPL revealed that the former had relatively reduced GFR (79.15 +/- 42.04 vs. 96.78 +/- 51.20 ml/min per 1.73 m(2); p < 0.006) and increased proteinuria (198.29 +/- 142.17 vs. 118.31 +/- 80.07 mg/m(2) per 24 h; p < 0.036). In comparison to the reference values of the normal population, the GFR was reduced and proteinuria was increased in the group with high BPL. Based on our results, pre-hypertension in children with high BPL seems to be associated with reduced GFR and increased proteinuria. A reasonable doubt remains that the patients with higher proteinuria and larger reduction of GFR may harbor an as yet unknown subclinical renal condition responsible for the onset of pre-hypertension. Therefore, children with even mildly elevated BP are at risk of developing renal damage and should change their lifestyle to prevent further increases in BP.

Ambulatory blood pressure monitoring in healthy children with parental hypertension

The aim of this study was to compare ambulatory blood pressure monitoring (ABPM) parameters in offspring with at least one hypertensive parent (HP) to offspring with normotensive parents (NP) and to determine whether gender of parent or child might influence the association between parental hypertension and blood pressure (BP). Eighty-nine healthy children (mean age 11.1 +/- 3.9 years) with HP and 90 controls (mean age 10.5 +/- 3.1 years) with NP were recruited. Age, gender, and height did not differ between the two groups, whereas children of HP had higher weight, body mass index (BMI), and waist circumference compared with healthy controls. No difference was found in casual BP between the two groups. In contrast, during ABPM daytime and nighttime mean systolic and diastolic BP and mean arterial pressure (MAP) standard deviation scores (SDS) were significantly elevated in children with HP. The mean percentage of nocturnal BP decline (dipping) was not significantly different between the two groups. Children with hypertensive mothers had higher daytime systolic and MAP SDS than controls; no such difference was detected for children with hypertensive fathers. Daytime systolic and MAP SDS were significantly elevated in boys with HP compared with boys with NP but failed to be significant in girls. Multiple linear regression analysis showed that parental history of hypertension (B = 0.29) and BMI (B = 0.03) were independently correlated with increase of daytime MAP SDS. Early changes in ambulatory BP parameters were present in healthy children of HP. BP in HP offspring was influenced by the gender of the affected parent and the offspring.

Reproducibility of home and ambulatory blood pressure in children and adolescents

OBJECTIVE

To evaluate the reproducibility of blood pressure measured at home (HBP) in comparison with ambulatory (ABP) and clinic blood pressure (CBP) in children and adolescents.

PARTICIPANTS AND METHODS

Individuals aged 8-17 years who had been referred for elevated CBP were included. CBP was measured at two visits, HBP on 5 days and ABP for 24 h. A second session including all the above measurements was performed after 8 weeks. The reproducibility of CBP (second visit of each session), HBP (average of days 2-5 of each session) and ABP (average 24-h, awake and asleep) was quantified using test-retest correlations coefficients (r) and the standard deviation of differences (SDD) between repeated measurements.

RESULTS

Sixteen individuals were included [mean age 13.3+/-2.9 (SD)] years, range 8-17, nine boys]. According to Task Force CBP criteria, eight were classified as hypertensives, three as high normal and five as normotensives. The reproducibility of HBP (systolic/diastolic r, 0.74/0.82, SDD 7.0/4.3) was superior to that of CBP (r, 0.63/0.80, SDD 10.4/6.3). However, ABP appeared to provide the most reproducible values (r, 0.87/0.84, SDD 5.5/4.3 for 24-h ABP; r, 0.85/0.76, SDD 5.9/5.0 for awake; r, 0.76/0.79, SDD 7.0/5.0 for asleep ABP). Aspects of the diurnal ABP variation were poorly reproducible (r, 0.62/0.14, SDD 6.8/5.5 for awake-asleep ABP difference; r, 0.55/0.26, SDD 0.07/0.11 for awake : asleep ratio).

CONCLUSION

These data suggest that in children and adolescents home blood pressure measurements are more reproducible than clinic measurements. However, 24-h ambulatory monitoring appears to provide the most reproducible blood pressure values.

Discrepancies in office and ambulatory blood pressure in adolescents: help or hindrance?

The goal of this commentary is to review the most relevant topics concerning the clinical utility of ambulatory blood pressure (BP) monitoring, such as the state of the art "reference BP values", the importance of the discrepant situations between office and ambulatory BP (white-coat and masked hypertension) and those of the recommended clinical indications to now. From a small number of studies, operational thresholds to define hypertension have been established. They are useful tools even though more studies are necessary to create strong reference values. Ambulatory BP measurement is increasingly recognized as being indispensable to the diagnosis and management of hypertension, and it has contributed significantly to our understanding of hypertension by revealing or "unmasking" BP phenomena that were not readily apparent using traditional techniques of measurement in clinical practice. Ambulatory BP monitoring should be performed in adolescents with either office mild essential hypertension before starting antihypertensive drug treatment or a strong family history of hypertension or an early cardiovascular event. Obese children with normal office BP values will also benefit from ambulatory BP monitoring. Other indications are the assessment of refractory hypertension or drug-induced hypotension. Finally, additional BP information in chronic renal failure, diabetes, and autonomic neuropathy can be obtained by using ambulatory BP monitoring.

Comparison of ambulatory blood pressure and Task Force criteria to identify pediatric hypertension

The aim of this study was to assess the level of agreement between central European ambulatory blood pressure monitoring (ABPM) and American Task Force (TF) criteria when applied to blood pressure (BP) measurements collected by ABPM to evaluate patients with hypertension. In 169 patients, we applied both sets of criteria and calculated mean daytime and nighttime BP and daytime BP loads. The frequency of hypertension for daytime systolic BP was significantly higher when TF criteria were used (p <or= 0.001). However, the frequency of hypertension for nighttime systolic BP was significantly increased when ABPM criteria were applied (p <or= 0.01). Therefore, with daytime ABPM measurements, hypertension was overdiagnosed with TF criteria, while nighttime hypertension was underdiagnosed using TF criteria. In contrast with previous reports, 40% of our patients with essential hypertension showed absence of nighttime dipping, regardless of the criteria used. The number of hypertensive patients was significantly higher using ABPM compared to TF criteria when patients with BP load >or=50% were evaluated (p <or= 0.01). Therefore, current recommendations for ABPM use in children such as to define white coat hypertension or as a screening tool to differentiate between primary and secondary hypertension need to be validated using yet to be produced normative ABPM criteria in American children.

Blood pressure, renal function, and proteinuria in children with unilateral renal agenesis

BACKGROUND/AIM

Unilateral renal agenesis (URA) is a model for a reduced nephron number that is believed to be a risk factor for blood pressure (BP) elevation and reduced renal function. The aim of the study was to investigate BP and renal function in children with URA.

METHODS

Data on children with URA from two pediatric nephrology centers were firstly retrospectively reviewed (renal ultrasound and scintigraphy, clinical BP, creatinine clearance, urinalysis). Children with normal renal ultrasound and scintigraphy were thereafter investigated using ambulatory BP monitoring.

RESULTS

Twenty-nine children with URA were investigated--14 children with an abnormal kidney (mostly scarring) and 15 children with healthy kidneys. Hypertension was diagnosed on the basis of clinical BP in 57% of the children with abnormal kidneys and on the basis of ambulatory BP monitoring in 1 child (7%) with healthy kidneys. The mean ambulatory BP in children with normal kidneys was not significantly different from that in controls. Forty-three percent of the children with abnormal kidneys had a reduced renal function, but none of children with normal kidneys.

CONCLUSIONS

Children with abnormalities of a solitary kidney have often hypertension, proteinuria, or a reduced renal function. In contrast, children with healthy solitary kidneys have BP and renal function similar to those of healthy children.

The choice of threshold limits for pediatric ambulatory blood pressure monitoring influences clinical decisions

OBJECTIVES

Hypertension in children may be defined by blood pressure elevated above the 95th percentile according to sex and age. Population data for ambulatory blood pressure provide different age-related and sex-related threshold limits to office-derived data. We sought to determine whether, when using ambulatory blood pressure monitoring in a clinical setting, changing 95th percentile threshold limit sets from office-derived to ambulatory blood pressure-derived would lead to different diagnostic decisions.

METHODS

Three nephrologists who were blinded as to patient identity and limit setting method reported on 42 ambulatory blood pressure records from a mixed group of patients aged 5-18 years by using both office-derived threshold limits for the 95th centile of blood pressure and ambulatory blood pressure-derived limits. Decisions regarding the presence or absence of hypertension were compared for each patient according to the limit set.

RESULTS

Thirty-five (83%) patients were considered to be hypertensive when office-derived threshold limits were used and 20% (P=0.005) fewer records were reported as showing hypertension when ambulatory blood pressure-derived threshold limits were used. When ambulatory blood pressure limits were applied, there were fewer records with an awake systolic blood pressure load >50% (P=0.004) and the average awake systolic blood pressure load was significantly lower (P<0.001).

CONCLUSION

Ambulatory blood pressure normative data tend to provide higher blood pressure limits for age and sex. Consequently, when ambulatory blood pressure data are used to set threshold limits, clinical decisions based on ambulatory blood pressure may be different than when office limits are used. These findings demonstrate the importance of using the most appropriate limit sets to analyze ambulatory blood pressure and when interpreting ambulatory blood pressure-based research.

Hypertension in young children and neonates

Hypertension is most often considered a disease of old age, but the precursors are often present in young children long before the clinically accepted definitions of hypertension in the adult are manifested. Essential hypertension is by far the most common form of the disease, comprising a complex interaction of genetic and environmental factors. Many individual genes that play a role in the maintenance of blood pressure have been identified; however, none has been shown specifically to be a component of essential hypertension. Hypertension is among the leading risk factors for coronary heart disease, stroke, and end-stage renal disease, making it critically important to identify individuals at risk early in life prior to manifestation of clinical signs and symptoms.

White-coat hypertension and masked hypertension in children

The use of ambulatory blood pressure monitoring in addition to the conventional office measurements makes possible the detection of individuals with white-coat hypertension and masked hypertension. In children referred for elevated blood pressure, both these phenomena appear to be common (10-15% for each). In a population of healthy children, white-coat hypertension appears to be as common as hypertension, whereas masked hypertension appears to be more common than white-coat hypertension or hypertension. In children with persistent white-coat or masked hypertension, assessment of target organ damage by echocardiography is required. Preliminary evidence suggests that, in contrast to white-coat hypertension, which is not associated with target organ damage, masked hypertension in children is associated with increased left ventricular mass. Children with masked hypertension should be followed up and possibly treated for hypertension if the phenomenon persists or there is evidence of target organ damage.

Effect of stimulants on 24-h ambulatory blood pressure in children with ADHD: a double-blind, randomized, cross-over trial

Millions of children with attention deficit hyperactivity disorder (ADHD) are treated with stimulant medications. To evaluate cardiovascular risk, 24-h ambulatory blood pressure monitoring (ABPM) was performed on and off medication. Thirteen subjects underwent APBM both on stimulant therapy and placebo using a placebo-controlled, double-blind, randomized, cross-over design. After a 3-day run-in followed by a 24-h monitoring period, subjects crossed over to the alternate therapy for repeated ABPM. Subjects demonstrated elevations in most hemodynamic parameters derived from ABPM during the active treatment period. Total diastolic blood pressure (69.7 mmHg vs 65.8 mmHg, p =0.02) and waking diastolic blood pressure (75.5 mmHg vs 72.3 mmHg, p =0.03) were significantly higher during active treatment. Total heart rate was also significantly higher during active treatment (85.5 beats/min vs 79.9 beats/min, p =0.004). The rate-pressure product (the product of systolic blood pressure x heart rate), an index of myocardial oxygen demand, was higher during active treatment (9,958 vs 9,076, p =0.008). This study provides evidence for a possible negative cardiovascular effect of stimulant medications in children with ADHD. This potential cardiovascular risk should be balanced against the beneficial behavioral effects of this class of medication.

Agreement on reporting of ambulatory blood pressure monitoring in children

The use of ambulatory blood pressure monitoring (ABPM) can improve the accuracy of paediatric BP measurement and may better correlate with end-organ injury than office BP measurement. However, the interpretation of ABPM may be influenced by several variables. We sought to ascertain the agreement among three paediatric nephrologists when reporting 92 ABPM sessions performed on patients aged 5 to 18 years. All three nephrologists were in agreement on the presence or absence of hypertension in 64% of cases. They were less likely to concur about records where hypertension was borderline or if the ABP record contained fewer BP readings. These results highlight the need for evidence-based consensus regarding the interpretation of ABPM in children.

Reduced nocturnal blood pressure dip and sustained nighttime hypertension are specific markers of secondary hypertension

OBJECTIVE

To investigate with the use of ambulatory blood pressure (BP) monitoring whether nocturnal BP dip and nighttime BP values are different in children with untreated primary and secondary hypertension.

STUDY DESIGN

Ambulatory BP monitoring studies from 145 children with untreated hypertension were retrospectively analyzed. Forty-five children had primary hypertension and 100 children had secondary hypertension.

RESULTS

Children with secondary hypertension had lower nocturnal BP dip for systolic and diastolic BP in comparison to children with primary hypertension (8% +/- 5% vs 14% +/- 4% for systolic and 14% +/- 7% vs 22% +/- 5% for diastolic BP, P < .0001 for both). Eleven percent of children with primary hypertension were classified as nondipper (BP dip <10%) for systolic BP and no child for diastolic BP; on the contrary, in children with secondary hypertension, 65% were nondippers for systolic and 21% for diastolic BP. Nocturnal systolic and diastolic BP loads were significantly greater in children with secondary hypertension than in those with primary hypertension.

CONCLUSIONS

Reduced nocturnal BP dip and sustained nighttime BP elevation are specific markers of secondary hypertension in children with untreated hypertension. Children with blunted nocturnal BP dip or sustained nighttime hypertension should be thoroughly investigated searching for the underlying cause of hypertension.

Office and out-of-office blood pressure measurement in children and adolescents

Office and out-of-office blood pressure measurements are being used for the diagnosis of hypertension in children and adolescents. The US National Heart, Lung, and Blood Institute have recently presented a new classification of blood pressure. On the basis of office measurements the 90th, 95th and 99th percentile for gender, age and height are used to classify children and adolescents as normotensive, pre-hypertensive and stage-1 or stage-2 hypertensive. Although auscultation using a standard mercury sphygmomanometer remains the recommended method, accumulating evidence suggests that ambulatory blood pressure monitoring is useful for the detection of white-coat hypertension and the prediction of target organ damage in children and adolescents. Studies have shown ambulatory blood pressure to be more reproducible than office measurements and normative tables for ambulatory measurements have been developed from cross-sectional studies in children and adolescents. In regard to home measurements in children, there are limited data from small trials showing lower blood pressure levels than daytime ambulatory blood pressure. In conclusion, ambulatory blood pressure monitoring is already finding a role as a supplementary source of information in children and adolescents, whereas at present home measurements should not be used for decision making in this population.

Ambulatory blood pressure correlates with renal volume and number of renal cysts in children with autosomal dominant polycystic kidney disease

OBJECTIVE

In adult patients with autosomal dominant polycystic kidney disease (ADPKD) renal volume was found to be significantly greater in hypertensive compared to normotensive patients. The purpose of this study was to find out if blood pressure (BP) is related to renal size also in children with ADPKD, for example, in an early stage of the disease.

METHOD AND RESULTS

Sixty-two children with ADPKD and normal renal function (mean age 12.3+/-4.3 years) were examined by renal ultrasound and ambulatory BP monitoring (ABPM). Twenty-two children were hypertensive and 40 normotensive. Mean renal volume was significantly greater in hypertensive than in normotensive children (2.7+/-2.3 SDS versus 1.2+/-2.5 SDS, P<0.01) despite similar anthropometric data and renal function. Similarly the mean number of cysts was significantly higher in hypertensive patients than in normotensive (35+/-15 cysts versus 23+/-14 cysts, P<0.01). Renal volume correlated with daytime as well as with night-time systolic and diastolic BP (r=0.41-0.47, P<0.01). Correlations with renal length and the number of renal cysts were somewhat less (r=0.29-0.43, P<0.05 and 0.01, respectively).

CONCLUSIONS

This study revealed a significant relationship between renal volume, renal length and number of renal cysts and BP. It is suggested that children with ADPKD should regularly be checked for BP changes by ABPM, especially those who show increased renal size or a high number of renal cysts on ultrasound. All these children are at high risk for development of hypertension.

Elevated blood pressure and decreased cognitive function among school-age children and adolescents in the United States

OBJECTIVE

To evaluate the relationship between elevated blood pressure (BP) and cognitive test performance in a nationally representative sample of children. Study design The National Health and Nutrition Examination Survey III provides cross-sectional data for children 6 to 16 years, including BP and cognitive test scores. Elevated BP was defined as systolic or diastolic BP >or=90th percentile. Cognitive tests were compared for children with elevated and normal BP. Linear regression was used to evaluate the relation between elevated BP and decreased test scores.

RESULTS

Among the 5077 children, 3.4% had systolic BP >or=90th percentile and 1.6% diastolic BP >or=90th percentile. Children with elevated systolic BP had lower average scores compared with normotensive children for digit span (7.9 vs 8.7, P=.01), block design (8.6 vs 9.5, P=.03), and mathematics (89.6 vs 93.8, P=.01). Elevated diastolic BP was associated with lower average scores on block design (9.5 vs 11, P=.01). Linear regression showed that elevated systolic BP was independently associated with lower digit span scores (P=.032).

CONCLUSION

Children with elevation of systolic BP are at risk for central nervous system end-organ damage, as manifested by decreased digit span test scores.

24-Hour BP in Children With Congenital Central Hypoventilation Syndrome

OBJECTIVE

To study circadian BP patterns in patients with congenital central hypoventilation syndrome (CCHS).

DESIGN

Case-control study.

SETTING

Teaching hospital in Paris, France.

PATIENTS

Eleven patients with CCHS (median age, 13 years; range, 6 to 18 years) and 11 sex- and height-matched control subjects.

INTERVENTION

None.

METHODS

Each subject underwent 24-h ambulatory BP monitoring. Oxygen saturation and end-tidal PCO(2) were monitored noninvasively. Polysomnography was performed to determine sleep times. All patients with CCHS received mechanical ventilation during sleep. Mean values for systolic BP (SBP) and diastolic BP (DBP) during wakefulness and sleep were analyzed. Nocturnal BP "dipping" was defined as the difference in mean SBP (and/or DBP) between wakefulness and sleep, divided by individual waking mean values. BP "dippers" were defined as subjects showing at least 10% nocturnal dipping.

RESULTS

Patients with CCHS had BPs in the low normal range of normative data. As compared to control subjects, patients with CCHS had lower BP during wakefulness (p = 0.003 and p = 0.016 for SBP and DBP, respectively), and higher BP during sleep (p = 0.016 and p = 0.002). Nocturnal BP dipping was abnormally reduced in patients with CCHS (p = 0.000). Ten of the 11 patients with CCHS were BP nondippers, compared to none of the control subjects.

CONCLUSION

The abnormal circadian BP pattern observed in children and adolescents with CCHS may be related to autonomic nervous dysfunction. Lifelong cardiovascular follow-up is recommended for patients with CCHS.

Essential hypertension

Hypertension is a frequent, chronic, age-related disorder, which often entails debilitating cardiovascular and renal complications. Blood pressure is usually noted in combination with other cardiovascular risk factors. Diagnosis of hypertension increasingly relies on automated techniques of blood pressure measurement. The pathophysiology of essential hypertension depends on the primary or secondary inability of the kidney to excrete sodium at a normal blood pressure. The central nervous system, endocrine factors, the large arteries, and the microcirculation also have roles in the disorder. Although monogenic forms of blood pressure dysregulation exist, hypertension mostly arises as a complex quantitative trait that is affected by varying combinations of genetic and environmental factors. Non-pharmacological strategies can reduce blood pressure. Antihypertensive drug treatment diminishes the complications of hypertension. The concept that a few major genes will provide the final clue to the pathogenesis of essential hypertension is an oversimplification that contradicts the heterogeneous nature of this disorder. Further integration of genetic, molecular, clinical, and epidemiological research could disclose subsets of patients in whom specific combinations of genetic and environmental factors raise blood pressure, and might lead to more individualised treatment.

Blood pressure in late adolescence and very low birth weight

OBJECTIVES

To determine whether blood pressure (BP) differed between very low birth weight (VLBW; birth weight <or=1500 g) subjects and normal birth weight (NBW; birth weight >2499 g) subjects in late adolescence, and to determine whether growth restriction in utero was related to BP in VLBW survivors at this age.

METHODS

This was a cohort study of 210 preterm survivors with birth weights <1501 g born from January 1, 1977, to March 31, 1982, and 60 randomly selected NBW subjects from the Royal Women's Hospital, Melbourne. BP was measured at 18+ years of age in 156 (74%) VLBW subjects and 38 (63%) NBW subjects with both a standard mercury sphygmomanometer and an ambulatory BP monitor.

RESULTS

VLBW subjects had higher sphygmomanometer systolic and diastolic BPs than NBW subjects (mm Hg; mean difference [95% confidence interval]; systolic, 8.6 [3.4, 13.9]; diastolic, 4.3 [1.0, 7.6]). VLBW subjects also had significantly higher mean systolic ambulatory BPs (mm Hg; mean difference [95% confidence interval]) for the 24-hour period (4.7 [1.4, 8.0]), and for both the awake (5.0 [1.6, 8.5]) and asleep (3.6 [0.04, 7.1]) periods. There were no significant differences between the birth weight groups for any ambulatory diastolic BPs. Within the VLBW subjects, there was no significant relationship between birth weight standard deviation score and any measure of BP.

CONCLUSIONS

BP was significantly higher in late adolescence in VLBW survivors than in NBW subjects. Growth restriction in utero was not significantly related to BP in VLBW survivors.

Ambulatory blood pressure monitoring in children and adolescents

With recent technological advances, 24-hour ambulatory blood pressure (BP) monitoring (ABPM) has become a useful tool for the evaluation, diagnosis, and management of hypertensive children. It provides a more accurate representation of an individual's BP rather than intermittent casual or office BP measurements. Hence, ABPM is being used more often to assess the BP of children. In this comprehensive review, we provide the reader with the available literature on ABPM, discuss the advantages and limitations of ABPM, and the interpretation of ABPM data. The role of ABPM in various clinical conditions and hypertension research in children is presented.

Systemic Hypertension: Management in Children and Adolescents

Recognition of systemic hypertension in children and adolescents requires careful blood pressure measurement using proper technique to compare with appropriate normative data. Selected use of ambulatory blood pressure monitoring can identify children with "white coat" hypertension, thus avoiding unnecessary diagnostic testing and treatment in these children. Nonpharmacologic therapies including dietary sodium restriction, weight loss, and exercise may benefit children and adolescents with borderline hypertension and mild essential hypertension. These therapies may be important adjunctive agents in children requiring antihypertensive therapy as well. Historically, pharmacologic management of hypertension in children has been limited by a lack of controlled studies and age-appropriate formulations. Recent clinical trials have provided new information regarding a number of antihypertensive agents in this age group.

Task Force II: blood pressure measurement and cardiovascular outcome

OBJECTIVE

To reach a consensus on the prognostic significance of new techniques of automated blood pressure measurement.

METHODS

A Task Force on the prognostic significance of ambulatory blood pressure monitoring wrote this review in preparation for the Eighth International Consensus Conference (28-31 October 2001, Sendai, Japan). This synopsis was amended to account for opinions aired at the conference and to reflect the common ground reached in the discussions.

POINTS OF CONSENSUS

(1) Prospective studies in treated and untreated hypertensive patients and in the general population have demonstrated that, even after adjusting for established risk factors, the incidence of cardiovascular events is correlated with blood pressure on conventional as well as ambulatory measurement. Ambulatory monitoring, however, significantly refines the prediction already provided by conventional blood pressure measurement. (2) White-coat hypertension is usually defined as an elevated clinic blood pressure in the presence of a normal daytime ambulatory blood pressure. Event-based studies in hypertensive patients have convincingly demonstrated that the risk of cardiovascular disease is less in patients with white-coat hypertension than in those with higher ambulatory blood pressure levels even after controlling for concomitant risk factors. Based on prognostic evidence, white-coat hypertension can now be defined as a conventional blood pressure that is persistently equal to or greater than 140/90 mmHg with an average daytime ambulatory blood pressure of below 135/85 mmHg. The issue of whether or not white-coat hypertension predisposes to sustained hypertension needs further research. (3) There is a growing body of evidence showing that a decreased nocturnal fall in blood pressure (<10% of the daytime level) is associated with a worse prognosis, irrespective of whether night-time dipping is studied as a continuous or a class variable. (4) Intermittent techniques of ambulatory blood pressure monitoring are limited in terms of quantifying short-term blood pressure variability. Proven cardiovascular risk factors such as old age, a higher than usual blood pressure and diabetes mellitus are often associated with greater short-term blood pressure variability. After adjusting for these risk factors, some - but not all - studies have nevertheless reported an independent and positive relationship between cardiovascular outcome and measures of variability of daytime and night-time blood pressure, for example standard deviation. (5) Reference values for ambulatory blood pressure measurement in children are currently based on statistical parameters of blood pressure distribution. In children and adolescents, functional rather than distribution-based definitions of ambulatory hypertension have yet to be developed. (6) Several studies of gestational hypertension have shown that, compared with office measurement, ambulatory blood pressure monitoring is a better predictor of maternal and fetal complications. Pregnancy is a special indication for ambulatory monitoring so that the white-coat effect can be measured and pregnant women are not given antihypertensive drugs unnecessarily. (7) Ambulatory pulse pressure and the QKD interval are measurements obtained by ambulatory monitoring that to some extent reflect the functional characteristics of the large arteries. The QKD interval is correlated with left ventricular mass, and ambulatory pulse pressure is a strong predictor of cardiovascular outcome. (8) Under standardized conditions, the self-measurement of blood pressure is equally as effective as ambulatory blood pressure monitoring in identifying the white-coat effect, but further studies are required to elucidate fully the prognostic accuracy of self-measured blood pressure in comparison with conventional and ambulatory blood pressure measurement.

CONCLUSIONS

Ambulatory blood pressure measurement refines the prognostic information provided by conventional blood pressure readings obtained in the clinic or the doctor's office. Longitudinal studies of patients with white-coat hypertension should clarify the transient, persistent or progressive nature of this condition, particularly in paediatric patients, in whom white-coat hypertension may be a harbinger of sustained hypertension and target-organ damage in adulthood. Finally, the applicability, cost-effectiveness and long-term prognostic accuracy of the self-measurement of blood pressure should be evaluated in relation to conventional blood pressure measurement and ambulatory monitoring.

Overview of ambulatory blood pressure monitoring in childhood and pregnancy

Despite the fact that the study and applicability of ambulatory blood pressure in children and pregnant women share characteristics which limit the potential development of knowledge for their use, advances produced in the last few years provided the present knowledge regarding the significance and the potential use of ambulatory blood pressure in children and in the pregnant women. In children ambulatory blood pressure monitoring is useful for the diagnosis of mild hypertensives, assessment of refractory hypertension, therapeutic trials with antihypertensive drugs, and clinical investigation when BP is one of the parameters to be taken into account and/or when subtle BP abnormalities are the objective of the study. In pregnant women, the main applicability is to assess the maternal and fetal risk in the hypertensive disorders of pregnancy.

Evaluation and management of hypertension in childhood

Hypertension, a relatively uncommon problem in childhood except in certain groups of children, is an important cardiovascular risk factor that can have significant health implications, especially the tendency for an elevated blood pressure in childhood to predict the development of adult hypertension. Common causes of childhood hypertension include renal and cardiac disease, as well as essential hypertension in adolescents. Given these factors, it is usually possible to evaluate the hypertensive child in a focused manner that should reveal not only the underlying cause of hypertension, but also its severity. Treatment should incorporate non-pharmacologic approaches as well as antihypertensive medications, and should take into account other cardiovascular risk factors such as hyperlipidemia. This review highlights these and other important issues in the evaluation and management of hypertensive children, and provides practical guidance to the practitioner involved in caring for such patients.

White coat hypertension in children

Ambulatory blood pressure monitoring (ABPM) has become more widely used in the assessment of elevated blood pressure in children. The accurate diagnosis of white coat hypertension (WCH) is particularly important in children because detection of elevated blood pressure often results in expensive and invasive diagnostic procedures to detect underlying disease. Recent normative pediatric data have both enhanced our ability to interpret ABPM results in pediatric patients and increased awareness that children suffer from WCH as has already been reported in adults. The few studies of WCH in children report a prevalence ranging from 44-88%, depending on the choice of threshold values for normalcy. When persistent hypertension is confirmed by three blood pressure measurements on three different occasions, ABPM should be performed as part of the initial evaluation. If hypertension is confirmed by ABPM, further evaluation should be tailored to the individual patient depending on the age, severity of hypertension, associated risk factors, and presence of end-organ injury.