First-attack pediatric hypertensive crisis presenting to the pediatric emergency department

From January 2000 to January 2008, we conducted this retrospective chart review of all patients 18 years and under with a diagnosis of HTN in our pediatric ED of Changhua Christian Hospital, a 2500-bed medical center in central Taiwan. The exclusion criteria were as follows: a BP below the 95^th percentile, a final diagnosis of transient hypertension, asymptomatic hypertensive patients, and those with incomplete data including inadequate body height or weight data, and no repeated BP measurements. A total of 112 patients presented to our pediatric ED with the diagnosis of primary and secondary hypertension. Sixteen patients were excluded for having a BP less than the 95^th percentile, 28 were excluded for asymptomatic hypertension, 10 were excluded due to a final diagnosis of transient hypertension, and three were excluded due to inadequate data. Therefore, the study group comprised 55 patients with hypertensive crisis. The study was approved by the Human Subjects Review Committee of the hospital.

The patients were divided into four age groups: infants (less than one year of age); preschool age (one to six years of age); elementary school age (seven to 12 years of age); and adolescents (13 to 18 years of age). Patients with hypertensive crisis were further subcategorized into two severity groups: hypertensive urgency and hypertensive emergency. Severity was based on the presence of end organ damage. Staging of HTN was defined as a BP between the 95^th percentile and 99^th percentile plus 5 mmHg (stage 1) and above the 99^th percentile plus 5 mmHg (stage 2).

All children above three years of age received initial BP measurements at our pediatric ED when triaging. With the exception of children who were bedridden and infants who were unable to sit, BP was checked with the children in a seated position with their backs supported, feet on the floor, right arm supported, and with the cubital fossa at heart level. An appropriate cuff size was used with an inflatable bladder width that was at least 40% of the arm circumference at a point midway between the olecranon and the acromion. The cuff bladder length covered 80 to 100% of the circumference of the arm. Initially, aneroid manometers (automatic devices) were used to measure BP with an appropriate cuff. If the systolic BP (SBP) or diastolic BP (DBP) was higher than 120/80 mmHg, it was re-measured from both hands and legs [15]. BP measurements were performed every hour in the patients who presented with an unstable BP and in the patients requiring further observation. During the study period, the BP measurements were performed by different nurses, all of whom were well-trained and qualified.

HTN in children more than 12 months of age was defined according to BP standards based on gender, age and height as stipulated in the updated classification of hypertension by the National Blood Pressure Education Program Working Group on Hypertension in Children and Adolescents [7]. HTN was identified when the SBP or DBP was greater than or equal to the 95^th percentile; stage 1 HTN was defined as an SBP or DBP within the range of the 95^th percentile to the 99^th percentile plus 5 mmHg; stage 2 HTN was an SBP or DBP greater than the 99^th percentile plus 5 mmHg. For the patients younger than 12 months of age, hypertension was defined as an SBP or DBP greater than the 95^th percentile for infants of a similar age, size and sex according to a previously published report [16]. When systolic and diastolic percentiles differed, they were categorized according to the higher value. Transient HTN means transient blood pressure elevation caused by any emotional, painful, or uncomfortable events, and was defined as an asymptomatic BP higher than the 95^th percentile only once or twice, but returning to less than the 95^th percentile on the second or third measurement without any antihypertensive medication [5].

A hypertensive emergency was defined as HTN in the presence of acute or ongoing target-organ lesions, or HTN in relation to an immediate life-threatening event requiring immediate intervention to reduce the BP [9, 11, 13]. Hypertensive urgency was defined as an elevation in SBP/DBP higher than the 99^th percentile plus 5 mmHg with any complication related to the HTN and no evidence of target-organ lesions. End organ damage was defined as impairment in renal, myocardial, hepatic, and hematologic functions, and neurological manifestations derived from HTN. Acute (transient) end organ damage resulting from HTN was identified by abnormal clinical and laboratory findings which subsided after a decrease in BP. Abnormal data included abnormal electrocardiography findings, impaired renal function tests, elevated liver function markers, and neurological manifestations such as headache, altered consciousness and dizziness.

Hypertensive encephalopathy is a specific clinical syndrome characterized by acute neurological change in the setting of sudden and/or prolonged HTN that overcomes the autoregulatory capacity of the cerebral vasculature [17, 18]. The syndrome is defined as severe hypertension in conjunction with symptoms of headache, altered mental status, seizure, or visual disturbances, and commonly presents with reversible posterior leukoencephalopathy seen on T2-weighted brain magnetic resonance images [19‐22].

The following data were collected and analyzed: age, gender, weight, height, family history of HTN, BP on arrival to the ED, clinical manifestations of hypertensive crisis (dizziness, headache, nausea/vomiting, visual symptoms, seizure/type, altered consciousness, chest tightness/pain, target-organ damage), reversibility, anti-hypertension drugs, underlying causes (renal disease, cardiovascular (CV), essential HTN, central nervous system (CNS) factors, endocrine/metabolic disorders, oncological disease), recurrent episodes, brain imaging and duration of hospitalization (ward/intensive care unit (ICU)). In addition, to decrease the influence of age, exact BMI percentile and z-score (standard deviation score), and SBP/DBP z-score according to the Center for Disease Control (CDC) growth charts were also analyzed.

CNS factors referred to CNS abnormalities as the cause of hypertension, which is different from hypertensive encephalopathy in causal connection. Essential hypertension was diagnosed after excluding secondary causes of hypertension by multiple tests, such as electrocardiography, metabolic panel, renal function tests, hemoglobin and urine routine tests, or other further specific tests including echocardiography, renal ultrasound, plasma rennin activity, plasma aldosterone, thyroid-stimulating hormone and 24-hour urine free cortisol.

Case distributions of hypertensive emergency and urgency were surveyed based on different time periods. During the study period, the BP levels, etiology, severity, and clinical manifestations were compared among children by age group and compared between the patients with hypertensive emergency and hypertensive urgency.

All statistical analyses were performed using Fisher’s exact test, the Kruskal Wallis test, Jonckheere Terpstra test, and chi-square test as appropriate. The results of the descriptive analyses of independent variables were reported as percentages and mean ± S.D. A P value less than 0.05 was considered statistically significant. Statistical analyses were performed using SPSS software (version 15.0; SPSS Inc., Chicago, IL, USA).

From 2000 to 2007 55 children presented to the ED with hypertensive crisis, including 46 cases (83.6%) with hypertensive urgency and 9 cases (16.4%) with hypertensive emergency (incidence ratio 5:1). Five children had a diagnosis of hypertensive encephalopathy. The male-to-female incidence ratio was 5:1 (boys, n = 46; girls, n = 9). Most patients were in the adolescent group (n = 24, 43.6%). A family history of hypertension was only noted in the patients older than preschool age (n = 8, 14.5%). Almost all of the pediatric hypertensive crisis patients presented with hypertension stage 2 (n = 54, 98.1%). The major symptoms of hypertensive crisis were headache (n = 30, 54.5%), followed by dizziness (n = 25, 45.5%), and nausea/vomiting (n = 20, 36.4%) (Figure 1). The leading underlying causes were essential hypertension (n = 26, 47.2%), followed by renal disease, and endocrine/metabolic disease. The renal diseases included nephrotic syndrome (n = 2, 14.3%), IgA nephropathy (n = 2, 14.3%), poststreptococcal glomerulonephritis (n = 1, 7.1%), end stage renal disease (ESRD), Henoch-Schönlein purpura with glomerulonephritis (n = 1, 7.1%), ureteropelvic junction obstruction (n = 1, 7.1%), Alport syndrome with ESRD (n = 1, 7.1%), focal segmental glomerulosclerosis with ESRD (n = 1, 7.1%), polycystic kidney (n = 1, 7.1%), Alstrom syndrome with chronic renal insufficiency (n = 1, 7.1%), inborn error, hyperammonemia with ESRD (n = 1, 7.1%), ESRD s/p renal transplantation (n = 1, 7.1%), and SLE with lupus glomerulonephritis (n = 1, 7.1%). The endocrine and metabolic diseases included hyperthyroidism (n = 3, 33.3%), diabetes mellitus (n = 3, 33.3%), hyperaldosteronism (n = 1, 11.1%), adrenal hyperplasia (n = 1, 11.1%), and methylmalonic academia with hyperuricemia (n = 1, 11.1%). The oncological disorders included pheochromocytoma associated with neurofibromatosis (n = 1, 50%) and paraganglioneuroma (n = 1, 50%). The recurrence rate of hypertensive crisis was 29.1% (16 cases: 12 urgency; 4 emergency) during the study period. A total of 33 (60%) patients who visited the ED were hospitalized: 24 to wards, 7 to the pediatric intensive care unit (PICU), and 2 to the pediatric observation unit (POU) of the pediatric ED.

Boys had a higher morbidity of hypertensive crisis in every age group except for the infant group (Table 1). A positive family history was present only in the children older than 7 years: 2 (10.5%) in the school age group, and 6 (25%) in the adolescent group. About half of the patients had underlying causes (n = 27, 49%). Essential HTN was also diagnosed in approximately half of the patients (n = 26, 47.3%). Among the underlying causes, essential HTN had a significant correlation with age (Table 1). The z-scores of BMI and SBP/DBP in the children by age group are listed in Table 2. The mean BMI values of the children with hypertensive crisis were all above the threshold of obesity. The mean SBP/DBP in the patients with hypertensive crisis was 161/102 mmHg. In contrast to DBP, SBP had a significant trend with older age. The patients with hypertensive crisis received antihypertensive agents, and the BP levels gradually decreased by about 25% to 30% within one hour, finally returning to normal ranges about two to three days later during hospitalization.

Five male patients, all without a family history of hypertension, had hypertensive encephalopathy at the ages of 5, 9, 12, 13 and 14 years, respectively (Table 3). Their presenting BP levels at the ED were all classified as stage 2 hypertension, and four of them had a DBP and SBP above the 99^th percentile plus 5 mmHg, ranging from 148 to 231 mmHg of systolic BP, and 86 to 172 mmHg of diastolic BP. All had altered consciousness; three were in a coma on arrival and recovered after their BP had been controlled. The major associated symptoms were headache and nausea/vomiting. Oncological causes were the major factors in the patients with hypertensive encephalopathy, one being induced by pheochromocytoma and one by paraganglioneuroma. Two of the patients with hypertensive encephalopathy had recurrent hypertensive crisis episodes during the study period. Magnetic resonance imaging (MRI) of the brain revealed increased signal intensity in the subcortical white matter and cortical gray matter of the parieto-occipital area, cerebellum and basal ganglia. Magnetic resonance spectrometry (MRS) showed a high lactate peak with normal N-acetyl aspartate (NAA), choline and creatine levels (Table 3).

The year and month distribution analysis of hypertensive urgency and emergency is shown in Figure 2. The analysis revealed that the prevalence of children with hypertensive crisis in the total number of children who came to the ED increased by year during the study period. The distribution by month revealed that hypertensive emergency occurred mostly in the spring (March to June).

During the study period, there were no cases of mortality or sequelae. Nine patients received multi-antihypertensive agents. Long-term-acting amlodipine besylate was used in seven patients; atenolol in nine patients; captopril in six patients; nifedipine in four patients; carvedilol, inderol and labetalol were used separately in three cases; and pentoxifylline, servidipine, lisinopril, and nicametate were each used once. None of the patients received antihypertensive medication before arriving at the pediatric ED.