Ambulatory blood pressure monitoring and hypertensive target-organ damage in children.

In contrast to the large number of studies relating high blood pressure to morbidity and mortality in adulthood, relatively few studies evaluating outcomes of children with hypertension have been conducted. Results of recent studies evaluating hypertensive target-organ injury in childhood suggest that early abnormalities, including left ventricular hypertrophy, glomerular hyperfiltration, and retinopathy, occur more commonly than had formerly been believed, and in children with mild elevations of blood pressure. Ambulatory blood pressure monitoring may be an important tool for use in evaluating hypertensive target organ damage in children and adolescents.

Effect of hyperparathyroidism on response to erythropoietin in children on dialysis.

The response to recombinant human erythropoietin (rHuEPO), 50 units/kg thrice weekly, was studied prospectively in 17 children and adolescents with end-stage renal disease who were either transfusion dependent or had hematocrits < 25%. For convenience, rHuEPO was given intravenously to 12 hemodialysis (HD) patients and subcutaneously to 5 peritoneal dialysis (PD) patients. Blood pressure, hematocrit, iron indices, and serum potassium, calcium, phosphorus, alkaline phosphatase, urea nitrogen, and intact parathyroid hormone (PTH) were monitored serially. When serum ferritin was < 100 ng/ ml during therapy, 6 patients received iron supplementation. rHuEPO therapy eliminated frequent transfusions in all patients; 11 of 17 patients reached the target hematocrit of 30%-33% by week 16 of rHuEPO, 50 units/kg thrice weekly. The 5 PD patients treated subcutaneously reached target at week 6 +/- 1; 6 HD patients treated intravenously reached target at week 11 +/- 3; 6 additional HD patients never reached target at this dose; 5 of 6 had pre-rHuEPO serum PTH levels >400 pg/ml, significantly higher than those of the other patients (P < 0.005); 3 of 6 later reached a hematocrit of 30%-33% after the rHuEPO dose was increased to 120-130 units/kg thrice weekly. We conclude that most pediatric dialysis patients can be treated successfully with rHuEPO, 50 units/kg thrice weekly, unless the serum PTH concentration is markedly elevated, in which case a higher dose is likely to be needed.

Influence of diurnal blood pressure variations on target organ abnormalities in adolescents with mild essential hypertension.

As hypertensive target-organ damage has been associated with diminished diurnal blood pressure (BP) variation in adults, we compared diurnal BP patterns of hypertensive adolescents with left ventricular hypertrophy with normotensive and hypertensive adolescents with normal left ventricular mass. In addition, the frequency of microalbuminuria (Malb), hyperfiltration, and reduced renal functional reserve (RFR) was evaluated in adolescents with normal BP and untreated borderline and mild essential hypertension. Thirty-three normotensive (NT) adolescents, 14.5+/-2.1 years (mean +/- SD), and 29 untreated borderline and mildly hypertensive (HT) adolescents, 14.6+/-2.4 years, wore the SpaceLabs 90207 ambulatory BP monitor for 24 h. Left ventricular mass was measured by M-mode echocardiography and then indexed (LVMI) to the cube of height. Creatinine clearance (Clcr) and urine Malb was measured on 24 h collection and RFR by change in creatinine clearance after an oral protein load. Diurnal BP change was expressed as the absolute and percent day-night BP fall and cusum derived plot height (CPH) and circadian alteration magnitude (CDCAM). Groups were compared using analysis of covariance with adjustments for race, gender, and body mass index. All NT and 19 HT subjects (HT-1) had normal LVMI at 22.2+/-5.3 and 25.8+/-3.8 g/m3, respectively. Ten HT (HT-2) had increased LVMI of 36.9+/-5.2 g/m3. No significant difference was found for absolute or percent day-night BP fall or CDCAM between groups. Nocturnal systolic BP was correlated most closely with LVMI (r = 0.41, p = .001). Clcr, Malb, and RFR did not differ between the groups. In conclusion, adolescents with borderline and mild essential hypertension and left ventricular hypertrophy have similar levels of diurnal BP fall, urine Malb excretion, and RFR compared to normotensive and hypertensive adolescents with normal left ventricular mass.

Relationship of renal size, body size, and blood pressure in children.

Somatometric parameters, renal size, and systolic blood pressure (SBP) were studied in 406 patients referred to pediatric nephrology and urology clinics. These patients included 269 females (66%), 67 African Americans (17%), and 87 patients with essential hypertension (21%). Z scores for the study population were comparable to published standards for height, kidney length, and SBP. Weight and body mass index scores were significantly greater than predicted from the standards, especially in the subset of patients with essential hypertension. Age, height, weight, body mass index, kidney length, and SBP all correlated with one another; however, on multiple regression analysis of SBP with the other five independent variables, only weight proved to have a significant correlation. Furthermore, the relationship of kidney length with SBP was positive and hypertensive patients had greater kidney size than published standards. These data do not support reduced kidney size in the population with essential hypertension, nor is there support for a convincing correlation between kidney length and SBP in the general pediatric population. Body weight correlates best with blood pressure. These findings warrant further study in a less-select population. Prevention and treatment of obesity may thus be of prime importance in addressing hypertension in children.

Evaluation of home blood pressure monitors in children and adolescents.

OBJECTIVE: This study was designed to adapt commercially available home blood pressure monitors for use in children ages 4 to 18 years and to compare the recordings obtained from the adapted devices to those obtained using a standard mercury sphygmomanometer. METHODS: Sequential same-arm blood pressures were measured by trained observers in 106 children, ages 4 to 18 years, using a calibrated mercury-gravity manometer (reference device) as the standard method, and 3 test devices (an aneroid manometer and two semiautomated oscillometric devices). For each patient, mid-arm circumference was measured and appropriate blood pressure cuff size was selected. Systolic and diastolic pressures were measured by trained observers using the reference device and the aneroid manometer in accordance with criteria established by the Second Task Force on Blood Pressure Control in Children. Other than variation in cuff size, all manufacturers' recommendations were followed for each test device. RESULTS: Outcome was assessed using criteria established by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). The aneroid manometer consistently received a grade of A using BHS criteria and also passed using AAMI criteria. Neither of the two semiautomated monitors achieved a passing grade, although the Labtron monitor performed slightly better than the Marshall 85 monitor. CONCLUSIONS: Home blood pressure monitors must be validated for use in children prior to widespread use. Given appropriate training and verification of observer accuracy, the aneroid manometer can be recommended for home use in children ages 4 to 18 years.

Use of pump-assisted hemofiltration in children with acute renal failure.

In critically ill children, acute renal failure (ARF) is associated with a high mortality. To assess the outcome and complications of pump-assisted hemofiltration (PAHF) using a standard volumetric pump to regulate blood flow, we retrospectively reviewed our experience in 52 patients with ARF treated with PAHF from 1989 to 1995. These patients ranged in age from < 1 month to 19 years and in weight from 2 to 125 kg. The most common underlying diagnoses were congenital heart disease and infection. The duration of PAHF averaged 9 +/- 8 days (range 24 h to 43 days). Hemodiafiltration for solute control was required in 40 patients. Total fluid intake while on PAHF was 136 +/- 95 ml/kg per day, while urine output and ultrafiltration averaged 15 +/- 24 ml/kg per day and 89 +/- 58 ml/kg per day, respectively. Management of laboratory abnormalities was efficient with only 4 patients requiring 1 or 2 additional treatments of hemodialysis for control of uremia. Complications included hyponatremia in 13 patients, hypokalemia in 14 patients, hypovolemia in 8 patients, hyperglycemia in 6 patients, and bleeding in 9 patients. No complications specifically related to use of the volumetric infusion pump for PAHF were noted. PAHF using a volumetric infusion pump for blood flow regulation in critically ill children with ARF is a practical and efficient therapy.

Diurnal blood pressure patterns in normotensive and hypertensive children and adolescents.

As abnormalities in diurnal ambulatory blood pressure (BP) have been associated with hypertensive target organ damage in adults, we investigated the diurnal systolic BP (SBP) and diastolic BP (DBP) patterns of 54 normotensive children, age 13.4 +/- 3.0 years, and 45 untreated borderline and mildly hypertensive children, age 14.4 +/- 2.6 years. Subjects wore the SpaceLabs 90207 ambulatory BP monitor for 24 h. BP was measured q 15 min from 08.00-21.00 h then q 30 min from 21.00-08.00 h. Nocturnal BP fall, the night-day ratio and cusum derived measures were calculated from time-weighted daytime and night-time SBP and DBP. The groups were compared using analysis of covariance with adjustment for age, race, gender and body mass index. The influence of age, gender and race on the diurnal BP profile was also examined. Nocturnal SBP fall was greater in hypertensive compared to normotensive subjects (17.1 +/- 6.7 vs 14.6 +/- 7.1 mm Hg; unadjusted mean +/- s.d., P = 0.022). Normotensive and hypertensive groups did not differ in nocturnal DBP fall or SBP or DBP night-day ratio. Race appeared to influence the diurnal BP pattern as black subjects had less nocturnal SBP fall (12.9 +/- 6.9 vs 17.1 +/- 6.5 mm Hg; P < 0.005) and a higher night-day SBP ratio (90.1 +/- 5.3 vs 86.7 +/- 4.6%; P < 0.005) than white subjects. In conclusion, hypertensive children and adolescents have a similar diurnal BP pattern as their normotensive counterparts, except that the entire BP profile is shifted upward with a greater absolute fall in SBP at night. Race also appears to influence the diurnal BP profile of normotensive and hypertensive children and adolescents.

Pediatric renovascular hypertension.

Renovascular disease is a frequent cause of severe hypertension in children and may result in significant morbidity or mortality. Most children presenting with renovascular hypertension have few if any symptoms, but devastating neurologic injury and congestive heart failure are still too often observed. Several new radiographic techniques have been used to detect renovascular lesions, but none has yet demonstrated consistently superior results when compared with intra-arterial digital subtraction angiography. Renal venous renin sampling, duplex ultrasonography, and captopril-enhanced renal scintigraphy may be useful diagnostic adjuncts. Therapeutic objectives include cure of hypertension and restoration or preservation of renal function. At many institutions, percutaneous transluminal angioplasty has become the treatment of choice for patients with renal transplant artery stenosis and discrete, nonostial stenoses caused by fibromuscular dysplasia. More extensive lesions generally respond well to surgical correction. Chronic pharmacologic therapy is reserved for patients who do not respond to angioplasty or in cases in which the location or extent of involvement of the renal arterial system precludes surgical revascularization. Nephrectomy is usually reserved for kidneys that have minuscule function of irreparable vascular anomalies. An individualized approach to therapy is increasingly emphasized.

Dialytic management of childhood acute renal failure: a survey of North American pediatric nephrologists.

A 35-question survey was mailed to 19 pediatric nephrologists regarding dialytic management of acute renal failure (ARF). Fifteen surveys were returned (79%). The purpose of the survey was to determine which renal replacement therapies (RRT) are most frequently used in the management of children with ARF in North America. Nephrologists were also questioned about clinical factors that influence the decisions to initiate RRT and choice of a particular modality. Survey results showed that hemofiltration was the initial choice for RRT among nephrologists (median value 40%, range 0%-100%) more often in their patients in the past 12 months than peritoneal dialysis (median value 30%, range 0%-85%) or hemodialysis (median value 20%, range 0%-50%). Factors considered most important in the decision to initiate dialysis include abnormalities in serum potassium, fluid balance, blood pressure and nutritional needs. Patient size and dialysis access were additional factors considered important in the choice of RRT modality.

Pump-assisted hemofiltration in infants with acute renal failure.

Hemofiltration is accepted management for acute renal failure in critically ill patients. However, in infants, obtaining arterial access or adequate flow through the access is often difficult. We report our technique and experience with pump-assisted hemofiltration (PAHF) in ten infants with acute renal failure. In five patients, double-lumen venous catheters provided access, while two catheters at separate sites were used in the remaining patients. In all patients, hemofilters were used with standard intravenous tubing added to pre-filter tubing and placed through a standard volumetric infusion pump for regulation of blood flow. The infants, aged 5-575 days, weighed from 2.8 to 11.4 kg and had primary diagnoses of post-operative congenital heart disease in five, sepsis in four, and renal dysplasia in one. The duration of PAHF averaged 158 +/- 115 h (range 20-332 h). Complications included bleeding at a catheter or surgical site in one patient each and asymptomatic hyponatremia in five patients. Thus, with adequate nurse training, PAHF using a volumetric infusion pump for blood regulation can be acceptable therapy in acute renal failure in infants.

Characterization of insulin-like growth factor binding protein-3 in chronic renal failure serum.

IGF-binding protein-3 (IGFBP-3), usually found as glycosylated 41- and 38-kD forms, is the major serum IGFBP during extrauterine life. In normal serum IGFBP-3 binds one IGF peptide and one acid-labile (alpha) subunit in a high-molecular-weight (MW) complex of 150 kD. By RIA, an excess of IGFBP-3 is present in chronic renal failure (CRF) serum, where it reportedly accumulates at low MW (25-55 kD) rather than as part of the 150-kD complex. To further evaluate IGFBP-3 forms in CRF, sera were obtained from seven healthy adolescents and seven adolescents with CRF. By RIA, IGFBP-3 levels were higher in CRF than normal sera (15.4 +/- 2.2 versus 10.1 +/- 2.1 micrograms/mL). High-MW (150-kD) fractions of CRF and normal sera, obtained by neutral size-exclusion chromatography, had equal amounts of IGFBP-3 by RIA. However, a second RIA peak of IGFBP-3, present in low-MW (35-kD) fractions of CRF but not normal sera, could account for the higher IGFBP-3 levels of CRF serum. [125I]IGF ligand blots of whole serum and serum fractions, either with or without prior precipitation by IGFBP-3 antiserum, found levels of 41- and 38-kD IGFBP-3 forms to be similar between CRF and normal whole sera and located these forms in the high-MW (150-kD) fractions of CRF and normal sera.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyponatremia.

This article provides a useful clinical classification of hyponatremic states based upon plasma tonicity and extracellular fluid volume. The pathophysiology of hyponatremia induced by hypovolemic, euvolemic, and hypervolemic conditions is discussed. An approach to the treatment of each category of hyponatremia is presented.