Although hypertension is a relatively uncommon disorder in pediatrics, its identified incidence is increasing, likely related to both heightened clinician awareness of the problem and increasing rates of obesity in children mediating earlier onset of high blood pressure.1-4 With adults, most hypertension is deemed to be primary or “essential” in etiology and often no diagnostic evaluation ensues. In children, on the other hand, primary hypertension has long been a diagnosis of exclusion and there has been consensus that hypertensive children need to undergo an evaluation to exclude any secondary causes to their hypertension, especially in the setting of significantly elevated blood pressures for a child’s age and body habitus.
Regardless of its cause, depending on the degree of elevation and the duration of onset, hypertension can lead to both acute and chronic organ dysfunction. In ambulatory settings, otherwise healthy hypertensive children have been found to be more likely to have left ventricular hypertrophy, accelerated atherosclerosis, proteinuria, and decreased cognitive function. In hospitalized children, hypertension may complicate the management of co-existing clinical conditions and there is the additional burden of determining whether the high blood pressure is a primary problem or whether it stems from an ongoing condition or its treatment.
Accordingly, a child who presents with hypertension often requires treatment while the diagnostic evaluation is ongoing. The approach to the evaluation and treatment of hypertension is often both more directed and more intensive in a hospitalized child than in an ambulatory setting. The extent of the blood pressure elevation and the degree of clinical concern for immediate harm to the child from the hypertension also guides the tempo of diagnostic evaluation and therapeutic intervention.
ASSESSMENT AND DEFINITION
MEASUREMENT OF BLOOD PRESSURE
With adults, blood pressure standards are based on epidemiologic outcome measures related to chronic end-organ damage seen in patients followed longitudinally with high blood pressure. In contrast, hypertension standards in children are based on statistical population norms since end organ effects may take decades to manifest. Currently, the “Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents”5 is used widely in North America to define blood pressure norms in children, and is more comprehensive than previously published standards.6
In children, normal blood pressure is defined as blood pressure measurements consistently falling below the 90th percentile compared to a pediatric reference group of comparable gender, age, and height. Prehypertension (formerly known as high-normal blood pressure) is defined as blood pressure at the 90th percentile or higher but less than the 95th percentile. Stage One Hypertension is defined as blood pressure at the 95th percentile or greater, and Stage Two Hypertension—or what used to be called severe hypertension—is that exceeding the 99th percentile.
Auscultation versus Oscillometry