Twenty-four-hour ambulatory blood pressure monitoring in infants and toddlers

Identifying barriers and utility of obtaining ambulatory blood pressure monitoring in a pediatric chronic kidney disease population

BACKGROUND

Hypertension is a prevalent complication of Chronic Kidney Disease (CKD) and Ambulatory Blood Pressure Monitoring (ABPM) is the gold standard for diagnosis. The aim of our study was to assess the usefulness of obtaining ABPM and to identify barriers to ABPM in this pediatric patient population.

METHOD

In this retrospective analysis of patients with CKD stage 3-5 who were seen in one academic medical center's outpatient Pediatric Nephrology clinics between 2018 and 2021, we performed logistic regression to evaluate for associations between demographic factors and odds of having an ABPM.

RESULT

Among 96 patients included in the study, 48 patients carried a diagnosis of hypertension. 31 patients had ABPM performed with usable data. In those who had ABPM done, 21 had normotension and 10 had undertreated hypertension. Our study also showed 1 had masked hypertension and 5 had white coat hypertension or effect. We did not find a statistically significant difference in those who did or did not undergo ABPM evaluation based on gender, previous diagnosis of hypertension, distance from clinic, language preference, or racial or ethnic identity.

CONCLUSION

ABPM is a useful tool in our CKD population for the diagnosis and management of hypertension. We did not identify specific barriers to ABPM in our CKD population, and there were no differences in patients who obtained ABPM when looking at specific demographic and disease characteristics. Given these findings, we recommend focusing on areas of future improvement in spheres of patient and provider education as well as better quantification using surveys to further illuminate barriers.

Nocturnal non-dipping on 24-h Ambulatory Blood Pressure Monitoring in children and adolescents with obesity is associated with higher total cholesterol levels

BACKGROUND

Few studies indicate the occurrence of abnormal nocturnal dipping of blood pressure (BP) in 35-50% of children and adolescents with obesity. The relation between that phenomenon and metabolic complications of obesity remains unclear. To evaluate the association between disorders of glucose and lipid metabolism, and nocturnal non-dipping in pediatric patients with obesity.

METHODS

In 207 children (53.14% girls, mean age 14 (range 2-17), mean BMI Z-SCORE 4.38, range 2.07-10.74) standard 24-h Ambulatory Blood Pressure Monitoring was performed. Normal dipping was defined as a ≥ 10% decline in BP during the night.

RESULTS

There were 106 (51.21%) cases of non-dippers. The mean 24-h nocturnal systolic BP (SBP) reduction (%) was 9.9 ± 5.5. The mean 24-h nocturnal diastolic BP (DBP) reduction (%) was 15.8 ± 8.5. There was a significant correlation between BMI Z-SCORE and mean day-time SBP (r = 0.14 P = .042). There are positive correlations between 24-h heart rate (beats/min) and BMI Z-SCORE (r = 0.15, P = .027), between fasting glucose and systolic BP Z-SCORE (r = 0.17, P = .03) and between mean diastolic BP and LDL cholesterol (r = 0.23, P = .004). Total cholesterol level was significantly higher in non-dippers (4.34 vs. 3.99 mmol/L, P = .034). There were no significant differences between non-dippers and dippers regarding fasting glucose (4.6 vs. 4.8 mmol/L), 120'post load glucose (5.7 vs. 5.9 mmol/L), insulin (19 vs. 20.2 µIU/mL), HOMA-IR (2.36 vs. 2.44), LDL cholesterol (2.64 vs. 2.51 mmol/L), HDL cholesterol (1.06 vs. 1.03 mmol/L) or triglycerides (1.36 vs. 1.34 mmol/L) levels.

CONCLUSION

Nocturnal non-dipping is frequent in pediatric patients with obesity. It is associated with higher total cholesterol levels.

Abnormal Ambulatory Blood Pressure and Early Renal Dysfunction in Sickle Cell Disease

OBJECTIVES

There is sparsity of studies evaluating blood pressure in children with sickle cell disease (SCD), which have shown inconsistent results. Few of the studies have documented lower office blood pressure (BP) in SCD patients, whereas, others have shown presence of masked hypertension and abnormal ambulatory blood BP monitoring (ABPM). Thus, the present study was conducted to examine 24 h ABPM parameters and renal dysfunction in children with SCD and compare them with healthy controls.

METHODS

A cross-sectional study was conducted on 56 children (30 children having SCD and 26 controls). ABPM and evaluation of renal functions including serum creatinine, serum urea, urinary creatinine, urinary protein and specific gravity was performed.

RESULTS

Spot urinary protein to creatinine ratio was found to be higher in patients with SCD (63.3%) as compared to controls (p < 0.001). Proteinuria was observed in 1/4th of the SCD patients less than ten years of age. Masked hypertension was present in 2 (6.6%) patients, ambulatory hypertension in 4 (13.3%), ambulatory pre-hypertension in 1 (3.3%) and abnormal dipping in 60%. A statistically significant correlation of BMI for age Z-score and standard deviation score (SDS/Z) of 24 h systolic BP (r = 0.56, p = 0.002); estimated glomerular filtration rate (eGFR) with 24 h diastolic BP SDS (r = -0.52; p = 0.038) and age with e GFR (r = 0.54; p = 0.025) was found in the present study.

CONCLUSIONS

The present study corroborates that ABPM abnormalities (ambulatory hypertension, non-dipping pattern, ambulatory prehypertension) and early onset proteinuria are significant findings in patients with SCD. This underscores the importance of regular screening for proteinuria and ABPM in routine care, for early detection and prevention of progressive renal damage in SCD.

Practical application of ABPM in the pediatric nephrology clinic

The use of 24-h ABPM has become commonplace when diagnosing and managing hypertension in the pediatric population. Multiple clinical guidelines recommend ABPM as the preferred method for identifying white-coat hypertension, masked hypertension, and determining degree of blood pressure (BP) control. Accurate, timely diagnosis and optimal management are particularly important in certain populations, such as children with chronic kidney disease (CKD), diabetes, and other conditions with increased risk for cardiovascular disease. Understanding how best to utilize ABPM to achieve these goals is important for pediatric nephrologists and other hypertension specialists. This review will provide practical information on the equipment, application, interpretation, and documentation of ABPM in the specialty clinic.

Behavior of Blood Pressure Variables in Children and Adolescents with Duchenne Muscular Dystrophy

Background

Duchenne muscular dystrophy is an X-chromosome-linked genetic disorder (locus Xp21). Involvement of the cardiovascular system is characterized by fibrous degeneration/replacement of myocytes with consequent ventricular hypertrophy and arterial hypertension.

Objective

To assess, by using 24-hour ambulatory blood pressure monitoring, the behavior of blood pressure variables in children and adolescents with a confirmed diagnosis of Duchenne muscular dystrophy.

Methods

Prospective observational cohort study, which selected 46 patients followed up on an outpatient basis, divided according to age groups. Blood pressure was classified according to the age percentile. The monitoring interpretation includes systolic and diastolic blood pressure means, systolic and diastolic blood pressure loads, and nocturnal dipping. The blood pressure means were calculated for the 24-hour, wakefulness and sleep periods. Nocturnal dipping was defined as a drop in blood pressure means during sleep greater than 10%. The significance level adopted was p < 0.05.

Results

Nocturnal dipping for systolic blood pressure was present in 29.9% of the participants. Approximately 53% of them had attenuated nocturnal dipping, and 15%, reverse nocturnal dipping. The age groups of 9-11 years and 6-8 years had the greatest percentage of attenuation, 19.1% and 14.9%, respectively. Regarding diastolic blood pressure, nocturnal dipping was identified in 53.2% of the children, being extreme in 27.7% of those in the age group of 6-11 years.

Conclusions

The early diagnosis of blood pressure changes can allow the appropriate and specific therapy, aimed at increasing the life expectancy of patients with Duchenne muscular dystrophy.

Kidney volume, kidney function, and ambulatory blood pressure in children born extremely preterm with and without nephrocalcinosis

BACKGROUND

Reduced kidney volume (KV) following prematurity is a proxy for reduced nephron number and is associated with the development of hypertension and end-stage renal disease in adults. We investigated whether extreme prematurity affects KV, function, and blood pressure in school-aged children and if nephrocalcinosis (NC) developed during the neonatal period had additional effects.

METHODS

We investigated 60 children at a mean age of 7.7 years: 20 born extremely preterm (EPT < 28 weeks gestational age with NC (NC+)), 20 born EPT without NC (NC-), and 19 born as full-term infants (control). We measured KV by ultrasound, collected blood and urine samples to evaluate renal function, and measured office and 24-h ambulatory blood pressure (ABPM).

RESULTS

Children born EPT had significantly smaller kidneys (EPT (NC+ NC-) vs control (estimated difference, 11.8 (CI - 21.51 to - 2.09 ml), p = 0.018) and lower but normal cystatin C-based glomerular filtration rate compared with control (estimated difference, - 10.11 (CI - 0.69 to - 19.5), p = 0.035). KV and function were not different between NC+ and NC- groups. Change in KV in relation to BSA (KV/BSA) from the neonatal period to school age showed significantly more EPT children with neonatal NC having a negative evolution of KV (p = 0.01). Blood pressure was normal and not different between the 3 groups. Fifty percent of EPT had a less than 10% day-to-night decline in ABPM.

CONCLUSIONS

Kidney growth and volume is affected by EPT birth with NC being a potential aggravating factor. Circadian blood pressure regulation seems abnormal in EPT-born children.

Use of ambulatory blood pressure monitoring in adolescents with SCI: a case series

Introduction

Due the impact of maturation on cardiovascular hemodynamics the degree of cardiovascular dysfunction, attributable to spinal cord injury (SCI), in the pediatric and adolescent population remains unclear. While few studies have begun to assess this, there is still a void in the literature regarding the prevalence of cardiovascular dysfunction and how best to identify and treat it in this population.

Case presentation

The purpose of this case series is to present the cardiovascular profile of three adolescent patients with chronic SCI, ages 14-16, following 2 or 3 days of 24-h Ambulatory Blood Pressure Monitoring (ABPM).

Discussion

We found that there are variations across the different cases in most cardiovascular hemodynamic categories and a clarification of the International Standards to document remaining Autonomic Function after Spinal Cord Injury (ISAFSCI) may be needed to accurately identify the remaining autonomic cardiovascular function in the adolescent SCI population.

Changes in arterial pressure and markers of nitric oxide homeostasis and oxidative stress following surgical correction of hydronephrosis in children

OBJECTIVE

Recent clinical studies have suggested an increased risk of elevated arterial pressure in patients with hydronephrosis. Animals with experimentally induced hydronephrosis develop hypertension, which is correlated to the degree of obstruction and increased oxidative stress. In this prospective study we investigated changes in arterial pressure, oxidative stress, and nitric oxide (NO) homeostasis following correction of hydronephrosis.

METHODS

Ambulatory arterial pressure (24 h) was monitored in pediatric patients with hydronephrosis (n = 15) before and after surgical correction, and the measurements were compared with arterial pressure measurements in two control groups, i.e. healthy controls (n = 8) and operated controls (n = 8). Markers of oxidative stress and NO homeostasis were analyzed in matched urine and plasma samples.

RESULTS

The preoperative mean arterial pressure was significantly higher in hydronephrotic patients [83 mmHg; 95% confidence interval (CI) 80-88 mmHg] than in healthy controls (74 mmHg; 95% CI 68-80 mmHg; p < 0.05), and surgical correction of ureteral obstruction reduced arterial pressure (76 mmHg; 95% CI 74-79 mmHg; p < 0.05). Markers of oxidative stress (i.e., 11-dehydroTXB₂, PGF_2α, 8-iso-PGF_2α, 8,12-iso-iPF_2α-VI) were significantly increased (p < 0.05) in patients with hydronephrosis compared with both control groups, and these were reduced following surgery (p < 0.05). Interestingly, there was a trend for increased NO synthase activity and signaling in hydronephrosis, which may indicate compensatory mechanism(s).

CONCLUSION

This study demonstrates increased arterial pressure and oxidative stress in children with hydronephrosis compared with healthy controls, which can be restored to normal levels by surgical correction of the obstruction. Once reference data on ambulatory blood pressure in this young age group become available, we hope cut-off values can be defined for deciding whether or not to correct hydronephrosis surgically.

MRI with ferumoxytol: A single center experience of safety across the age spectrum

Purpose

To summarize our single‐center safety experience with the off‐label use of ferumoxytol for magnetic resonance imaging (MRI) and to compare the effects of ferumoxytol on monitored physiologic indices in patients under anesthesia with those of gadofosveset trisodium.

Materials and Methods

Consecutive patients who underwent ferumoxytol‐enhanced (FE) MRI exams were included. Adverse events (AEs) were classified according to the Common Terminology Criteria for Adverse Events v4.0. In a subgroup of patients examined under general anesthesia, recording of blood pressure, heart rate, oxygen saturation, and end‐tidal CO₂ was performed. A comparable group of 23 patients who underwent gadofosveset‐enhanced (GE) MRI under anesthesia with similar monitoring was also analyzed.

Results

In all, 217 unique patients, ages 3 days to 94 years, underwent FE‐MRI. No ferumoxytol‐related severe, life‐threatening, or fatal AEs occurred acutely or at follow‐up. Two patients developed ferumoxytol‐related nausea. Between‐group (FE‐ vs. GE‐MRI) comparisons showed no statistical difference in heart rate (P = 0.69, 95% confidence interval [CI] 96–113 bpm), mean arterial blood pressure (MAP) (P = 0.74, 95% CI 44–52 mmHg), oxygen saturation (P = 0.76, 95% CI 94–98%), and end‐tidal CO₂ (P = 0.73, 95% CI 31–37 mmHg). No significant change in MAP (P = 0.12, 95% CI 50–58 mmHg) or heart rate (P = 0.25, 95% CI 91–105 bpm) was noted between slow infusion of ferumoxytol (n = 113) vs. bolus injection (n = 104).

Conclusion

In our single‐center experience, no serious AEs occurred with the diagnostic use of ferumoxytol across a wide spectrum of age, renal function, and indications. Because of the limited sample size, firm conclusions cannot be drawn about the generalizability of our results. Thus, vigilance and monitoring are recommended to mitigate potential rare adverse reactions.

Level of Evidence: 2

J. Magn. Reson. Imaging 2017;45:804–812.

Blood pressure (BP) assessment-from BP level to BP variability

The assessment of blood pressure (BP) can be challenging in children, especially in very young individuals, due to their variable body size and lack of cooperation. In the absence of data relating BP with cardiovascular outcomes in children, there is a need to convert absolute BP values (in mmHg) into age-, gender- and height appropriate BP percentiles or Z-scores in order to compare a patient's BP with the BP of healthy children of the same age, but also of children of different ages. Traditionally, the interpretation of BP has been based mainly on the assessment of the BP level obtained by office, home or 24-h BP monitoring. Recent studies suggest that it is not only BP level (i.e. average BP) but also BP variability that is clinically important for the development of target organ damage, including the progression of chronic kidney disease. In this review we describe current methods to evaluate of BP level, outline available methods for BP variability assessment and discuss the clinical consequences of BP variability, including its potential role in the management of hypertension.

Hypertension in chronic kidney disease: role of ambulatory blood pressure monitoring

Children with chronic kidney disease have a markedly increased risk of cardiovascular morbidity and children with end stage renal disease have an estimated 30 times greater risk of cardiovascular mortality than the general pediatric population. In adults, the link between hypertension and cardiovascular disease is well-documented but that association has not been so readily apparent in children with chronic kidney disease. This may be in part because the early changes in blood pressure that occur in these patients do not necessarily manifest with changes in casual blood pressure measurements. Ambulatory blood pressure monitoring, with its ability to gather multiple readings both during the normal activities of the day and the night, is felt to be a more veritable measure of blood pressure. Its use in children has been hampered by limited data on normative values and difficulties in blood pressure classification, while its use in adults is ever expanding. However, with an increasing number of studies in children with chronic kidney disease, ambulatory blood pressure has revealed a greater prevalence of abnormal findings in this population and has been shown to better predict cardiovascular risk than current standards. Two large multi-center studies in Europe and North America have revealed even greater utility of ambulatory blood pressure measures in this population. It is hoped that continued use of ambulatory monitoring in children will help overcome some of its perceived limitations while also validating its use in those at high risk of cardiovascular morbidity.

Strengths and limitations of current pediatric blood pressure nomograms: a global overview with a special emphasis on regional differences in neonates and infants

The availability of robust nomograms is essential for the correct evaluation of blood pressure (BP) values in children. A literature search was conducted by accessing the National Library of Medicine by using the keywords BP, pediatric and reference values/nomograms. A total of 43 studies that evaluated pediatric BP nomograms were included in this review. Despite the accuracy of the latest studies, many numerical and methodological limitations still remain. The numerical limitations include the paucity of data for neonates/infants and for some geographic areas (Africa/South America/East Europe/Asia) and ethnicities. Furthermore, the data on ambulatory BP and response to exercise are extremely limited, and the criteria for stress-test interruption are lacking. There was heterogeneity in the methodologies employed to perform the measurements, in the inclusion/exclusion criteria (often not reported), in the data normalization and the data expression (Z-scores/percentiles/mean values). Although most studies adjusted the measurements for age and/or height, the classification by specific age/height subgroups varied. Gender differences were generally considered, whereas other confounders (that is, ethnicity/geographic area/environment) were seldom evaluated. As a result, nomograms were heterogeneous, and when comparable, at times showed widely different confidence intervals. These differences are most likely because of both methodological limitations and differences among the populations studied. Some robust nomograms exist (particularly those from the USA); however, it has been demonstrated that if adopted in other countries/continents, they may generate an unpredictable bias in the evaluation of BP values in children. Actual pediatric BP nomograms present consistent limitations that affect the evaluation of BP in children. Comprehensive nomograms, which are based on a large population of healthy children (including neonates/infants) and use standardized methodology, are warranted for every country/region.

The late effects of anticancer therapy after childhood Wilm's tumor: the role of diastolic function and ambulatory blood pressure monitoring

OBJECTIVE

Wilms' tumor, or nephroblastoma, is the most common primary malignant renal tumor of childhood. The excellent outcome now expected for most children with this tumor is attributed to the combination of effective adjuvant chemotherapy, improved surgical and anesthetic techniques and also the radiosensitivity of the tumor. The numerous organ systems are subject to the late effects of anticancer therapy. The aim of this study was to investigate the blood pressure profile and ambulatory blood pressure monitoring, and also cardiac diastolic functions and pulmonary venous flow in 25 children with unilateral Wilms' tumor in remission.

METHODS

The patient group consists of 25 patients who successfully completed anticancer treatment for unilateral Wilms' tumor. Thirty-three age-, weight- and height-matched healthy children were considered as a control group for an echocardiographic study. Also, 20 age-, weight- and height-matched healthy children were considered as a control group for the ambulatory blood pressure monitoring study.

RESULTS

In our study, 24 h, daytime and night-time systolic blood pressure and night-time diastolic blood pressure measurements were found to be significantly increased in the patient group compared with healthy children. We detected diastolic filling pattern abnormalities. We also found increase in pulmonary venous flow (systolic and diastolic) in Wilms' tumor group.

CONCLUSIONS

We suggest the regular follow-up of survivors of Wilms' tumor for care and prevention of cardiovascular diseases.

Preschool children with obstructive sleep apnea: the beginnings of elevated blood pressure?

STUDY OBJECTIVES

In adults and older children, snoring and obstructive sleep apnea (OSA) are associated with elevated blood pressure (BP). However, BP has not been assessed in preschool children, the age of highest OSA prevalence. We aimed to assess overnight BP in preschool children with snoring and OSA using pulse transit time (PTT), an inverse continuous indicator of BP changes.

DESIGN

Overnight polysomnography including PTT. Children were grouped according to their obstructive apnea-hypopnea index (OAHI); control (no snoring, with OAHI of one event or less per hour), primary snoring (OAHI one event or less per hour), mild OSA (OAHI greater than one event to five events per hour) and moderate-severe OSA (OAHI more than five events per hour).

SETTING

Pediatric sleep laboratory.

PATIENTS

There were 128 clinically referred children (aged 3-5 years) and 35 nonsnoring community control children.

MEASUREMENT AND RESULTS

PTT was averaged for each 30-sec epoch of rapid eye movement (REM) or nonrapid eye movement (NREM) sleep and normalized to each child's mean wake PTT. PTT during NREM was significantly higher than during REM sleep in all groups (P < 0.001 for all). During REM sleep, the moderate-severe OSA group had significantly lower PTT than the mild and primary snoring groups (P < 0.05 for both). This difference persisted after removal of event-related PTT changes.

CONCLUSIONS

Moderate-severe OSA in preschool children has a significant effect on pulse transit time during REM sleep, indicating that these young children have a higher baseline BP during this state. We propose that the REM-related elevation in BP may be the first step toward development of daytime BP abnormalities. Given that increased BP during childhood predicts hypertension in adulthood, longitudinal studies are needed to determine the effect of resolution of snoring and/or OSA at this age.

Blood pressure regulation, autonomic control and sleep disordered breathing in children

Sleep disordered breathing (SDB) ranges in severity from primary snoring (PS) to obstructive sleep apnoea (OSA). In adults, SDB is associated with adverse cardiovascular consequences which are mediated, in part, by autonomic dysfunction. Although SDB is common in children, fewer paediatric studies have investigated these cardiovascular effects. Initial research focused on those with OSA, indeed children with PS were occasionally utilised as the comparison control group. However, it is essential to understand the ramifications of this disorder in all its severities, as currently the milder forms of SDB are often untreated. Methodologies used to assess autonomic function in children with SDB include blood pressure (BP), BP variability, baroreflex sensitivity, heart rate variability, peripheral arterial tonometry and catecholamine assays. The aim of this review was to summarise the findings of paediatric studies to date and explore the relationship between autonomic dysfunction and SDB in children, paying particular attention to the roles of disease severity and/or age. This review found evidence of autonomic dysfunction in children with SDB during both wakefulness and sleep. BP dysregulation, elevated generalised sympathetic activity and impairment of autonomic reflexes occur in school-aged children and adolescents with SDB. The adverse effects of SDB seem somewhat less in young children, although more studies are needed. There is mounting evidence that the cardiovascular and autonomic consequences of SDB are not limited to those with OSA, but are also evident in children with PS. The severity of disease and age of onset of autonomic consequences may be important guides for the treatment of SDB.

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.

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.

REM-related bradyarrhythmia syndrome

Cardiac arrhythmias during sleep are relatively common and include a diverse etiology, from benign sinus bradycardia to potentially fatal ventricular arrhythmias. Predisposing factors include obstructive sleep apnea and cardiac disease. Rapid eye movement (REM)-related bradyarrhythmia syndrome (including sinus arrest and complete atrioventricular block with ventricular asystole) in the absence of an underlying cardiac or physiologic sleep disorder was first described in the early 1980s. Although uncertain, the underlying pathophysiology likely reflects abnormal autonomic neural-cardiac inputs during REM sleep. The autonomic nervous system (ANS) is a known key modulator of heart rate fluctuations and rhythm during sleep and nocturnal heart rate reflects a balance between the sympathetic-parasympathetic systems. Whether the primary trigger for REM-related bradyarrhythmias reflects abnormal centrally mediated control of the ANS during REM sleep or anomalous baroreflex parasympathetic influences is unknown. This review focuses on the salient features of the REM-related bradyarrhythmia syndrome and explores potential mechanisms with a particular assessment of the relationship between the ANS and nocturnal heart rate fluctuations.

Superior consistency of ambulatory blood pressure monitoring in children: implications for clinical trials

BACKGROUND

Casual office blood pressure (CBP) measurements are still standard in antihypertensive drug trials. In pediatric hypertensive trials, ethical considerations, very low disease prevalence and the marked impact of white-coat hypertension create the need for very sensitive and reproducible techniques of BP assessment. We hypothesized that ambulatory BP monitoring (ABPM) may identify treatment effects more sensitively than CBP and thereby reduce sample sizes required in pediatric antihypertensive trials.

METHODS

Standard deviations (SDs) were used to assess population variability of CBP and ABPM at baseline and after 6 months standardized antihypertensive treatment from a trial investigating the BP-lowering effect of ramipril in children with chronic kidney disease.

RESULTS

In 157 hypertensive children, ramipril had a similar mean BP-lowering effect on clinic and ambulatory 24-h BP for systolic (-10 vs. -11 mmHg, P = NS) and diastolic values (-9 vs. -11 mmHg, P = NS). However, the SDs of the CBP responses were up to 39% larger than those of ABPM (SBP 15.5 vs. 9.4; DBP 13.8 vs. 8.8; both P < 0.0001). Using power analysis, we demonstrate that, depending on the magnitude of the expected antihypertensive effect and trial design, the utilization of ABPM in antihypertensive drug efficacy studies allows reduction of sample sizes by 57-75%. This reduction of cohort size with ABPM is substantially greater than previously observed for adults.

CONCLUSION

The primary use of ABPM can substantially reduce the number of children put at potential risk in blinded antihypertensive drug trials by up to three quarters.

Ambulatory blood pressure monitoring: a versatile tool for evaluating and managing hypertension in children

In recent years, pediatric practitioners have increasingly used ambulatory blood pressure (ABP) monitoring for evaluating blood pressure (BP) abnormalities in children. ABP monitoring in adults is superior to casual BP measurements for predicting cardiovascular morbidity and mortality, and whereas the association with target-organ damage in children is not as definitive, early evidence does seem to parallel the adult data. In addition to confirming hypertension at diagnosis, ABP monitoring may be useful for identifying isolated nocturnal hypertension, characterizing BP patterns, and assessing response to therapeutic interventions. This article reviews current evidence supporting the use of ABP monitoring in children and discusses limitations in our understanding of this technology, specifically focusing on indications for its use and interpretation of the large quantity of data obtained by ABP monitoring.

Ambulatory blood pressure monitoring and target organ damage in pediatrics

The prevalence of hypertension in children and adolescents is rising in association with the increasing rate of childhood obesity, and it is associated with early target organ damage. Published guidelines on high blood pressure in children and adolescents, focused on the early and accurate diagnosis of hypertension, resulted in improved ability to identify children with hypertension. Although auscultation using a mercury sphygmomanometer remains the method of choice for evaluation of hypertension in children, accumulating evidence suggests that ambulatory blood pressure monitoring is a more accurate method for diagnosis, and it is more closely associated with target organ damage. In addition, ambulatory blood pressure monitoring is a valuable tool in the assessment of white-coat hypertension, and masked hypertension in children and adolescents. Masked hypertension in children and adolescents is associated with a similar risk of target organ damage as in established hypertension.

Blood pressure in the first year of life in healthy infants born at term

Neonatal hypertension occurs in up to 2% of neonatal intensive care survivors and in up to 3% of all neonates. Normal blood pressure (BP) measurements are required to diagnose and manage appropriately both hypotension and hypertension in the neonate and infant. The aim of this study was to provide normative BP measurements during the first year of life of healthy infants born at term, using an oscillometric method. Neonates were enrolled from August 2003 to August 2005. Exclusion criteria included: infants of mothers with hypertension or diabetes of any type, use of illicit substances, congenital or chromosomal anomaly, admission to the neonatal intensive care unit or possible sepsis. There were 406 infants enrolled, with 150 children followed at 6 months of age and 118 children at 12 months of age. There were no differences in BP measurements at 6 months or 12 months of age by gender, weight or height. A BP measurement above the 90th percentile on day 2 or at 6 months was not predictive of a BP above the 90th percentile at 12 months of age. Higher systolic and diastolic measurements at 6 months and 12 months were found, in comparison to those in previous studies using ultrasonic devices. The findings of this study provide normative BP values for infants during their first year of life, using the oscillometric method, the most frequently used method in paediatric, neonatal intensive care and emergency departments.

Evaluation of hypertension by the general pediatrician

PURPOSE OF REVIEW

To summarize the recommended work-up in a child who presents with elevated blood pressure as well as innovative evaluation techniques under development.

RECENT FINDINGS

'The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents' contains several updates on the diagnosis, evaluation and treatment of childhood hypertension. New risk factors for hypertension have been identified and include obesity, sleep apnea, and low birth weight. The roles of uric acid, leptin and C-reactive protein in the pathophysiology of hypertension have been examined. The presence of hypertensive end-organ damage has been demonstrated in hypertensive children.

SUMMARY

Current knowledge emphasizes the need to diagnose and treat hypertension when it develops in childhood to decrease the risk of cardiovascular morbidity in adulthood. End-organ injury is evident, illustrated by the presence of left ventricular hypertrophy, even in young children. Assessment for the presence of comorbidities and end-organ damage should be emphasized. Further study is needed to isolate the etiologic factors for childhood hypertension, improve evaluation techniques, and determine if end-organ damage is reversible with proper therapy.

Ambulatory blood pressure monitoring: what a pediatrician should know

PURPOSE OF REVIEW

Ambulatory blood pressure monitoring is a useful tool for the evaluation and management of hypertension in children and adolescents. This review provides a basic overview of ambulatory blood pressure monitoring and summarizes the most recent available knowledge regarding its use in the pediatric population.

RECENT FINDINGS

Evaluation and validation of ambulatory blood pressure monitoring equipment in children remains limited, although advances in the interpretation of results for this age group have been reported specifically in the area of circadian (24 h) and ultradian (<24 h) variability. Blood pressure is a dynamic phenomenon that varies not only with time but also with changing patient and environmental circumstances. Growing evidence regarding conditions identified when this variability is considered, specifically white coat and masked hypertension, suggests that office blood pressure measurement may not be a sufficient screening test for hypertension-related target-organ damage.

SUMMARY

Information regarding ambulatory blood pressure monitoring use in children is increasing, although due to its limitations and expense, it remains a tool primarily utilized by the pediatric sub-specialist.

Ambulatory blood pressure monitoring and renal functions in children with a solitary kidney

The aim of this study is to investigate the blood pressure (BP) profile, microalbuminuria, renal functions, and relations with remaining normal kidney size in children with unilateral functioning solitary kidney (UFSK). Sixty-six children with UFSK were equally divided into three groups: unilateral renal agenesis (URA), unilateral atrophic kidney (UAK), and unilateral nephrectomy (UNP). Twenty-two age-, weight-, and height-matched healthy children were considered as a control group. The serum creatinine level and first-morning urine microalbumin and creatinine concentrations were determined by the standard methods. Also, the BP profile was determined by ambulatory blood pressure monitoring (ABPM). We found that the serum creatinine level was higher and creatinine clearance was lower in each patient groups compared to those of the control group (p < 0.05). Compared with the controls, each group of patients had mean office, 24-h, daytime, and night-time systolic and diastolic BP values similar to those of the controls (p > 0.05). An inverse correlation was found between the renal size standard deviation scores (SDS) of normal kidneys and 24-h systolic and diastolic BP load SDS in all of the patients (p < 0.05; r = -0.372, r = -0.295, respectively). The observed relationship between renal size SDS and 24-h mean arterial pressure (MAP), systolic and diastolic BP load SDS suggests that children with UFSK should be evaluated by using ABPM for the risk of hypertension.

Utility of ambulatory blood pressure monitoring in children and adolescents

Diagnosis of hypertension is critically dependent on accurate blood pressure measurement. "Accurate" refers to carefully following the guidelines for blood pressure measurement laid out for children and adults to minimize observer and subject errors that commonly occur in clinical blood pressure measurement. Accurate blood pressure measurement is more important in children and adolescents as the misdiagnosis of hypertension may have a life-long adverse impact on insurability and employment. Automated blood pressure measurement offers multiple advantages in achieving high-quality blood pressure determinations by reducing observer errors. The most commonly used form of automated blood pressure measurement is 24-h ambulatory blood pressure measurement (ABPM). Information on ABPM in children has grown exponentially over the last decade. Normative data exists for diagnosis of hypertension in children using ABPM including a novel method for determining normal values with the LMS method. There is further information about the utility of different determinants of 24-h blood pressure such as dipping status, morning surge and blood pressure load. ABPM has been able to detect significant differences in blood pressure in many disease states in children including chronic renal failure, polycystic kidney disease, solitary functioning kidney, and after renal transplantation. Increasingly nonambulatory automated blood pressure determinations have been used in management of hypertension in children. Although nonambulatory automated readings lack information about nocturnal blood pressure or blood pressure during daily activity, studies have suggested that home automated blood pressure measurements are a helpful adjunct to the usual office blood pressure reading.

Applications of 24-hour Noninvasive Ambulatory Blood Pressure Monitoring

Casual blood pressure (CBP) measurements using a standard sphygmomanometer have traditionally constituted the principal modality for the assessment and management of hypertension. However, CBP measurement has shortcomings. Ambulatory blood pressure monitoring (ABPM) provides abundant information on blood pressure (BP), including heart rate, all BP readings for test periods, BP average, BP variability, BP load, load index, distribution pattern of BP, reduction percentage of BP, trough/peak ratio, and summary statistics for overall 24-hour, daytime and nighttime periods. Over the last three decades, ABPM has evolved from a research device to an established and valuable clinical tool for assessment and management of hypertension. This technology has been proven to be useful in terms of the distribution pattern of BP, characterization of BP profiles in normotensive and hypertensive patients, evaluation of patients with mild or labile hypertension, physiologic and psychologic factors for fluctuation of BP, load index study, study of white coat hypertension, etiology of hypertension, prognosis of hypertension, and assessment of antihypertensive management. Nevertheless, the technology remains underused due to lack of insurance reimbursement in most countries. Accordingly, insurance reimbursement is crucial to promote increased utility of ABPM. Clinicians should be familiar with the role of this technology in the care of patients with abnormal BP. This review is an attempt to increase clinicians' understanding of ABPM and the appropriate use of this technology.

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.