Hypertension

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16.3 Hypertension

1 Hypertension is blood pressure that is consistently above the 95th percentile.

2 Severe hypertension is blood pressure that is consistently above the 99th percentile (i.e. 1% of children).

3 All hypertension should be investigated.

4 The most common secondary cause is renal disease.

5 Accelerated hypertension with encephalopathy is an emergency.

6 In malignant hypertension blood pressure should be lowered slowly.

7 Borderline hypertension is of uncertain significance, but needs follow up.

Introduction

In children, blood pressure (BP) is a continuous variable that is influenced by age, sex, body size, and genetic, circadian and environmental factors.

Hypertension is defined as BP that is consistently above the 95th percentile for age, gender and height (nomograms are available with these data and should be present in both the emergency department (ED) and paediatric wards) (Table 16.3.1).

Age Upper limit for normal systolic BP (95th percentile) Males Females 1 month 104 102 2 months 109 106 3 months 111 108 4 months 110 109 6 months 110 110 1 year 110 110 2 years 110 110 3 years 111 110 4 years 112 111 5 years 113 112 6 years 115 114 7 years 117 116 8 years 118 117 9 years 120 119 10 years 122 121 11 years 124 123 12 years 127 125 13 years 129 128 14 years 130 129 15 years 133 130 16 years 136 131

Data obtained with permission from the National Heart, Lung and Blood Institute of the United States National Institutes of Health.

Severe hypertension is BP consistently above the 99th centile with signs of end-organ damage such as retinopathy, nephropathy or left ventricular hypertrophy.

Accelerated hypertension occurs with severe hypertension plus neurological signs and symptoms (hypertensive encephalopathy) and severe hypertensive retinopathy.

Prevalence of hypertension is around 1–3% of children (note that this is to some extent a statistical issue related to use of BP centiles in defining hypertension). The most common secondary cause of hypertension in children is renal disease, though with increasing age (and the pandemic of childhood obesity) essential hypertension assumes more significance.

Ideally, all children presenting to ED should have a BP measurement.

History and examination

History

Ask about signs or symptoms of underlying disease, urinary tract infection (UTI), drugs, family history of renal disease or hypertension (essential or otherwise).

Non-specific signs and symptoms of hypertension in infants may include vomiting, irritability, respiratory distress, failure to thrive and congestive heart failure.

In older children, also consider polyuria, polydipsia, fatigability, headache, epistaxis, chest pain, abdominal pain and neurological abnormalities such as Bell’s palsy or impaired vision. Enquire regarding any noted deterioration in school performance and/or change in personality, as these can be seen in chronic hypertension.

Examination

Measurement of BP is ‘classically’ performed using a mercury sphygmomanometer (though these are no longer universally available, e.g. in the United Kingdom), with the largest possible cuff (do not be misled by labels on cuffs). The inflatable part should encircle the arm and the width should cover 75% of the length of the upper arm.

Increasingly, oscillometric BP machines (e.g. Dinamap) are routinely used in EDs and elsewhere. Automated devices need regular service and calibration. Elevated measurements should (if possible) be confirmed with a mercury sphygmomanometer.

BP should be checked in both arms and at least one leg to exclude the possibility of aortic coarctation. BP should be repeated after an interval in an attempt to exclude ‘white coat’ hypertension.

Ambulatory blood pressure monitoring is available for children and is a useful method of further evaluating BP as well as for monitoring treatment effects.

Feel all pulses. As well as a thorough general examination, physical assessment following identification of elevated blood pressure should consider specifically: presence or absence of encephalopathy, growth, hydration, signs of chronic disease and presence of abdominal masses or bruits (cardiac, cranial and abdominal). The optic fundi must be visualised, specifically looking for papilloedema and vascular changes.

Investigations

Investigations to be considered in ED include:

• full blood count, electrolytes, urea and creatinine, liver function tests (LFTs), calcium, phosphate, magnesium, alkaline phosphatase;

• urinalysis by dipstick for protein and blood;

• urine microscopy and culture;

• urine catecholamines;

• chest X-ray, electrocardiogram and echocardiography;

• abdominal and renal ultrasound scan, including grey-scale sonography to identify parenchymal and collecting system disease and tumours, colour and duplex Doppler sonography to identify vessel disease;

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