Hypertension

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Chapter 17 Hypertension

Deirdre Fearon, MD, MA, Susan Duffy, MD

1 What is considered high blood pressure or hypertension in a child?

There’s hypertension, and then there’s HYPERtension. The distinction is between significant (>95th percentile) and severe (>99th percentile) hypertension. These classifications by age and sex were established by the Task Force on Blood Pressure Control in Children, updated in 2004. In addition to these classifications, the Task Force also developed standardized definitions for hypertensive urgency and hypertensive emergency. Hypertensive urgency refers to a severely elevated blood pressure without evidence of end-organ damage. A hypertensive emergency occurs when a child’s blood pressure is severely elevated and the child shows evidence of end-organ damage.

Cronan K, Kost SI: Renal and electrolyte emergencies. In Fleisher GR, Ludwig S, Henretig FM (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, pp 873–919.

National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescence: The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics 114:555–576, 2004.

KEY POINTS: CLASSIFICATION OF HYPERTENSION

Depending on age, height, and sex:

Significant hypertension is >95th percentile.

Severe hypertension is >99th percentile.

Hypertensive urgency is >99th percentile without evidence of end-organ damage.

Hypertensive emergency is >99th percentile with evidence of end-organ damage.

2 If a high blood pressure is found incidentally by the triage nurse, what two questions should you ask before you get too worried?

“What size cuff did you use?” Inappropriate cuff size can give spuriously high or low blood pressure readings. They will be falsely elevated if the cuff is too small, and low if the cuff is too big. The width of the cuff bladder should be about 40% of the circumference of the arm measured at the midpoint between the shoulder and the elbow (technically, between the acromion and the olecranon). The cuff should encircle 80–100% of the circumference of the upper arm and be about two-thirds of its length.

“Will you please repeat it?” Nonpathologic elevations in blood pressure can be caused by white coats, pain, recent activity, heat, and agitation. Ideally, a child’s blood pressure should be measured after a few minutes of inactivity, as he or she sits calmly in a parent’s lap.

3 Which patients need evaluation and treatment in the emergency department (ED), and which patients can follow up with their primary physician?

Workup and treatment: Clearly, patients with hypertensive emergencies should be treated in your department, with the initial focus on ABCs and rapidly establishing IV access. Those children experiencing hypertensive urgencies (i.e., severely elevated blood pressures without evidence of end-organ damage), should be worked up, treated, and admitted for further evaluation.

Workup only: For asymptomatic patients with significantly elevated blood pressure readings, a thorough history and physical examination and some screening laboratory tests should be performed. If there are no abnormalities in this workup, the patient can be discharged with close follow-up.

Discharge without workup: Patients being seen for another problem who were incidentally found to have mildly elevated blood pressures and are asymptomatic can be discharged to the care of their primary care physician. Ideally, the doctor should record several readings in a series of visits before confirming the diagnosis of hypertension (Fig. 17-1).

Figure 17-1 Approach to the initial emergency department triage and stabilization of the hypertensive child.

From Linakis JG: Hypertension. In Fleisher GR, Ludwig S, Henretig FM [eds]: Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, with permission.

KEY POINTS: APPROACH TO THE HYPERTENSIVE CHILD

1 Work up, treat, and admit patients with blood pressure > 99th percentile or end-organ damage.

2 Work up and discharge patients with blood pressure > 95th percentile and normal screening laboratory test results.

3 Discharge with follow-up patients with incidentally found, mildly elevated blood pressure.

4 Name the causes of pathologic hypertension. Discuss likely causes in babies, small children, and big children.

In general, as the age of a child increases, the likelihood of finding a cause for hypertension decreases. A newborn infant with hypertension is most likely to have either a congenital renal anomaly or a vascular problem (e.g., a renal artery thrombosis or stenosis or coarctation of the aorta). Small children may present with these vascular or congenital causes but become more likely to have renal parenchymal disease such as pyelonephritis, glomerulonephritis, or reflux nephropathy. Big children and teenagers are most likely to have essential hypertension (including obesity), though may still present with parenchymal disease. The mnemonic HYPERTENSION may help you recall some of the major causes of high blood pressure:

Linakis JG, Constantine E: Hypertension. In Fleisher GR, Ludwig S, Henretig FM (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, pp 351–358.

5 How might a child present with hypertension?

Often hypertension is silent and picked up on routine physical examination. If a child does present with symptoms, they may be as vague as irritability and headache or as impressive as seizure and coma. Other possible symptoms include visual disturbances, personality changes, dizziness, nausea and vomiting, weight loss, polyuria and polydipsia, or facial nerve palsy.

6 What historical questions are important to ask the parent of a hypertensive child?

Does the child have a history of recurrent urinary tract infections? Unexplained fevers? Hematuria? Frequency? Dysuria? Any recent illness? Sore throats?

Did the child have an umbilical artery catheter as a neonate?

Does he or she have intermittent sweating, flushing, and palpitations?

Has the child been growing well?

Has the child suffered any recent head trauma?

Is there a family history of hypertension, renal disease, or deafness?

Has the child ingested anything? Decongestants? Birth control pills? Steroids? Cocaine?

8 What laboratory tests should you obtain in the initial workup of a patient with hypertension?

Much information can be obtained with relatively few laboratory tests. Usually a set of electrolytes with a blood urea nitrogen and creatinine, a complete blood count, and a urine dip are enough to get started in the asymptomatic patient. In obese children, a lipid profile may be helpful, as would a urine culture in all girls and those boys with known renal disease. In patients who are symptomatic, electrocardiography and chest radiography may help you determine the degree of end-organ damage. If ultrasonography is readily available in your department, renal ultrasonography can be particularly helpful in diagnosis of a renal cause of hypertension in a baby.

KEY POINTS: LABORATORY WORKUP FOR A HYPERTENSIVE CHILD

1 Urine dip (and culture if indicated)

2 Electrolytes, blood urea nitrogen, creatinine, with or without lipid profile

3 Electrocardiography and chest x-ray if patient is symptomatic

4 Renal ultrasonography if available

9 If a child has a dangerously high blood pressure, should it be lowered to normal as quickly as possible?

Well, sort of. It is important to normalize blood pressure to prevent further end-organ damage, but doing so too quickly can be harmful to those same organs, specifically the brain. Cerebral autoregulation maintains a relatively constant cerebral blood flow with variations in peripheral pressures. When peripheral blood pressure increases, cerebral vessels constrict. When peripheral pressure drops, those vessels dilate. There are points, however, at extremes of blood pressure, at which this system is exhausted. When the cerebral vessels are maximally constricted or dilated, the brain can no longer autoregulate. It is particularly important when treating a hypertensive emergency to bear in mind that under hypertensive conditions, the low point at which autoregulation ceases to function is raised (i.e., maximal cerebral vasodilatation occurs at a higher blood pressure). Lowering the blood pressure below this point can lead to cerebral ischemia. For this reason, an elevated blood pressure should be lowered to normal as slowly as is safely possible, ideally over days rather than minutes.

10 Discuss which medications you would use to treat hypertension in the ED.

Patients with hypertensive emergencies should be treated in the ED. The medicines you choose will depend on the patient’s current medications, the suspected cause of the hypertension, your comfort with particular medicines, and whether the child’s life is in danger. For non-life-threatening situations, nifedipine and hydralazine are both safe, effective choices. They begin to work about 10 minutes after administration and last for several hours. For immediate results in lowering a dangerously high blood pressure, a nitroprusside infusion will give dose-related effects that will cease within minutes of stopping the infusion. Another alternative is diazoxide, which acts within 3–5 minutes to vasodilate resistance vessels and reduce blood pressure. It is given in frequent small boluses until the desired blood pressure is reached, and lasts between 4 and 12 hours. Labetalol has rapid effects on both α- and β-adrenergic receptors; is somewhat difficult to titrate; and is contraindicated in patients with asthma, heart block, heart failure, and pheochromocytoma. Nicardipine is an effective calcium-channel blocker that acts quickly to reduce peripheral vascular resistance. Because pediatric experience with nicardipine is quite limited, it should be used with extreme caution in children. Figure 17-1 summarizes the approach to the hypertensive pediatric patient in the ED.

Linakis JG, Constantine E: Hypertension. In Fleisher GR, Ludwig S, Henretig FM (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, pp 351–358.

KEY POINTS: MEDICAL TREATMENT OF HYPERTENSION

1 Non-life-threatening: hydralazine or nifedipine

2 Life-threatening: nitroprusside

11 Name some other classes of medications that might be useful in the treatment of a hypertensive emergency.

Depending on the type of end-organ damage, treatment of complications associated with severely elevated blood pressures may be necessary. For example, lorazepam for seizures, diuretics for heart failure, and appropriate intubation medications should be available when treating a child with a hypertensive emergency.

12 An adolescent boy is brought to the ED at 5:00 am after a night out dancing. He is euphoric and diaphoretic, and has a dry mouth. He is tachycardic and hypertensive. You consider giving him a β-blocker, but think better of it. Why?

The patient has probably ingested an amphetamine-related compound, such as 3,4-methylenedioxymethamphetamine (MDMA or “ecstasy”). The cardiovascular effects of phenylethylamines are due to both α- and β-adrenergic stimulation. A β-blockade would leave α-unopposed and result in vasospasm and paradoxical hypertension. Instead, consider using nitroprusside or nifedipine.

Albertson TE, Van Hoozen BE, Allen RP: Amphetamines. In Haddad LM, Shannon MW, Winchester JF (eds): Clinical Management of Poisoning and Drug Overdose, 3rd ed. Philadelphia, W.B. Saunders, 1998, pp 560–568.

13 A school-aged child is in your ED being evaluated for an upper respiratory tract infection. You notice he is hypertensive on repeated measurements. He is an otherwise healthy child. When asked, he admits to some leg pain after playing soccer. He has a systolic ejection murmur. His radial pulses are bounding, but you have trouble feeling his dorsalis pedis pulses. What might be the cause of his hypertension?

Coarctation of the aorta can present after infancy, with hypertension as the presenting sign. Claudication symptoms and a heart murmur may or may not be present. It is important to feel for differential upper- and lower-extremity pulses in hypertensive patients of all ages, and to check four extremity blood pressures if there is any concern about coarctation of the aorta. In normal patients, lower-extremity blood pressures are higher than upper-extremity pressures by 10–20 mmHg. In patients with coarctation of the aorta, the blood pressure in the legs is lower than that in the arms.

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