The prevalence of pediatric hypertension has increased in recent decades. While still uncommon, pediatric hypertensive crisis is a potentially life-threatening condition and therefore requires physicians to have a thorough understanding of its presentation and management. There are numerous etiologies of hypertension to consider, but the goals of evaluation and management in the emergency department are to classify the severity of hypertension, identify specific etiologies requiring unique treatments, identify contraindications to urgent initiation of antihypertensive medications, determine proper therapy, if needed, and patient disposition.

In 2004, The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents (Fourth Report) defined hypertension in patients 1 to 17 years old as an average systolic or diastolic blood pressure ≥95th percentile for gender, age, and height on three or more occasions taken over weeks to months, except in the presence of severe hypertension.¹ In 2017, the Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents (Clinical Practice Guideline) provided new normative blood pressure tables based on normal-weight children and adolescents, excluding the overweight and obese individuals who were previously included in the derivation of the tables published in the Fourth Report.² In addition, the Clinical Practice Guideline replaced the term “prehypertension” with “elevated blood pressure” and revised the criteria for stage 1 and stage 2 hypertension, as shown in Table 44-1. The normative blood pressure tables provide data to classify hypertension in children and adolescents 1 to 17 years old; unfortunately, such robust information is lacking for neonates and infants. In 2012, Dionne and colleagues used the limited published data in the literature to derive a reference table of estimated blood pressure values for neonates and infants more than 2 weeks old from 26 to 44 weeks postmenstrual age (Table 44-2).³ For infants beyond 44 weeks postmenstrual age until 12 months old, the percentile curves published in the Report of the Second Task Force on Blood Pressure Control in Children in 1987 (Second Task Force) remain the most widely used reference (Figure 44-1).⁴

Hypertensive crisis is divided into two categories: hypertensive urgency and hypertensive emergency. An emergency manifests with acute end-organ damage, such as encephalopathy, acute kidney injury, and heart failure. Hypertensive urgency manifests with less significant symptoms, such as headache, nausea, and vomiting, without acute end-organ damage. Urgency may progress to emergency if left untreated. Since these categories of hypertensive crisis have not been rigorously defined, the distinction is not absolute and depends somewhat on clinical judgment.⁵ Nevertheless, it remains critical to remember that hypertensive urgency may progress to emergency if left untreated.

In the emergency department, all patients 3 years of age or older should have their blood pressure measured. Those younger than 3 years old should have their blood pressure measured under certain circumstances (Table 44-3). It is often difficult to accurately measure blood pressure by auscultation in patients less than 3 years old, which is why the use of oscillometric devices is preferred. Oscillometric device validation status should be checked, including whether the device is validated in the pediatric age group, at www.dableducational.org.² If an initial oscillometric blood pressure measurement is abnormal in a patient of any age, the initial measurement should be discarded and two additional oscillometric measurements obtained. If the average of these two measurements is ≥90th percentile for gender, age, and height, then the blood pressure should be measured twice using auscultatory technique and these two values averaged to determine the patient’s blood pressure classification.

An appropriate cuff size is one with an inflatable bladder width that is at least 40% of the arm circumference at a point midway between the olecranon and the acromion. The bladder length should cover 80% to 100% of the mid-arm circumference. For children in whom the appropriate cuff size is difficult to determine, the mid-arm circumference should be measured as illustrated in the Clinical Practice Guideline. Importantly, blood pressure measurements are overestimated to a greater degree with a cuff that is too small than they are underestimated by a cuff that is too large.¹ So, if a patient’s mid-arm circumference measurement is between two cuff sizes, the larger of the two cuffs should be used.

The bell of a stethoscope should be placed over the right brachial artery pulse to measure blood pressure by auscultation, unless the patient has known atypical aortic arch anatomy or has an arm circumference greater than 44 cm. In these cases, the left arm or a lower extremity should be used to measure blood pressure, respectively. When measuring blood pressure over a brachial artery pulse, the bell of the stethoscope should be placed proximal and medial to the cubital fossa and below the bottom edge of the cuff. If possible, have the patient sit quietly for 5 minutes prior to measuring, with his or her back supported, feet on the floor, right arm supported, and the cubital fossa at the level of the heart. To measure blood pressure in a lower extremity, the patient should be in the prone position and the cuff should be placed mid-thigh with the bell of the stethoscope over the popliteal artery. Recognize that blood pressure in the lower extremities is usually 10% to 20% higher than the brachial artery pressure. For neonates and infants, blood pressure should be measured in the supine position. If hypertension is confirmed and classified as stage 2, blood pressure should be measured in both arms and one lower extremity.

The epidemiology of hypertension in childhood and adolescence has changed due to the worldwide obesity epidemic. The prevalence has clearly increased over the past decades, with primary hypertension now being the predominant cause in patients 6 years of age and older.⁶ A recent large-scale retrospective pediatric study, including electronic health record data on more than 1.2 million patients across 27 states between 3 to 18 years old, found a prevalence of 3.3% for hypertension and 10.1% for elevated blood pressure.⁷ A prevalence of 3.3% means that 2.2 million children and adolescents in the United States have hypertension, making it one of the most common pediatric health concerns.⁸

The prevalence of pediatric hypertensive crisis is less well studied. A retrospective analysis performed in Taiwan found an incidence of 0.021% in a population of 531,400 patients visiting two pediatric emergency departments between 1995 to 2010.⁹ Of the patients diagnosed with hypertensive crisis, 98.2% had stage 2 hypertension, 43.6% were 13 to 18 years old, 34.5% were 7 to 12 years old, and the male to female ratio was 5.1:1. Regarding neonatal hypertension, an incidence ranging from 0.2 to 3% has been reported, with a higher occurrence among neonates who spent time in the neonatal intensive care unit.³

Pediatric hypertension has many etiologies; therefore, there are many pathophysiologic mechanisms to appreciate. However, there is one fundamental concept regarding hypertensive crisis that the emergency physician must keep in mind, which is vascular autoregulation. This physiologic process occurs in the vascular beds of several organs. For example, cerebral blood flow remains unchanged in normotensive adults between a mean arterial pressure (MAP) of 60 to 120 mmHg due to vascular autoregulation. As the MAP increases, compensatory cerebral vasoconstriction limits cerebral hyperperfusion. The autoregulation becomes overwhelmed, known as autoregulation breakthrough, at a MAP of approximately 180 mmHg, resulting in end-organ hyperperfusion, arteriolar fibrinoid necrosis, and increased endothelial permeability with perivascular edema.¹⁰

The threshold for autoregulation breakthrough in the pediatric patient depends on gender, age, and height, as well as the duration of hypertension. In patients with long-standing hypertension, a rightward shift in the autoregulation curve occurs (Figure 44-2).⁵ Knowledge of this shift in vascular autoregulation is critical to understand the reasoning for the recommended management of hypertensive crisis. Specifically, it is important to therapeutically decrease the patient’s blood pressure slowly to avoid ischemic damage to organs, such as the brain, heart, and kidneys, whose vascular beds have accommodated to elevated pressures and will not have prompt compensatory vasodilation in response to rapid reduction.

SYMPTOMATIC

Hypertensive crisis requires prompt recognition. The Studying Treatment of Acute hyperTension (STAT) registry is the largest publication to date evaluating the clinical presentation of patients with acute, severe hypertension managed in an emergency department or intensive care unit with intravenous antihypertensive medications.¹¹ The study included 1588 adult patients with a median age of 58 years. The authors defined severe hypertension as a single systolic blood pressure >180 mmHg or diastolic blood pressure >110 mmHg. It found the most common presenting symptoms in adults to be shortness of breath (29%), chest pain (26%), headache (23%), altered mental status (20%), and focal neurologic deficit (11%). In contrast, the pediatric literature remains less robust. A recent study including 55 patients 18 years old and younger, 84% with hypertensive urgency and 16% with hypertensive emergency, found the most common presenting symptoms to be headache (54.5%), dizziness (45.5%), nausea or vomiting (36.4%), and chest pain (29.1%).¹²