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;

• plasma renin and aldosterone (refer to lab regarding collection);

• complement C3, C4, anti-nuclear antibody (ANA);

• drug screen, (e.g. amphetamines);

• cranial computerised tomography (CT) scan.

Subsequent investigations will depend on results of preliminary investigations and on the underlying diagnosis.

Causes

There are many possible causes of hypertension:

Endocrine

• Catecholamine excess (neuroblastoma, phaeochromocytoma).

• Corticosteroid excess (congenital adrenal hyperplasia).

• Hyperthyroidism.

Vascular

• Aortic coarctation.

• Arteriovenous fistula.

• Takayasu arteritis.

• SLE.

Metabolic

• Diabetes.

• Porphyria.

• Hypercalcaemia.

Neurological

• Guillain–Barré syndrome.

• Raised intracranial pressure.

Drugs

• Steroids.

• Oral contraceptives.

• Stimulant medications (methylphenidate and dexamphetamine).

• Recreational drugs.

• Liquorice.

Toxins

• Heavy metals.

Miscellaneous

• Anxiety and pain.

• Burns.

• Essential hypertension.

Treatment

Hypertensive encephalopathy

Treatment for encephalopathy/accelerated hypertension is urgent. The blood pressure should be treated before proceeding with investigation of the underlying cause. Such patients should be discussed with a paediatric intensivist and nephrologist and will generally be admitted to the paediatric intensive care unit.

Aim initially for 25% reduction towards target BP (upper limit of normal systolic – see Table 16.3.1) in the first 12–24 hours, then the reduction should be slow, over 24–48 hours. Neglecting to lower the blood pressure can lead to permanent disability or death. Acutely lowering the blood pressure to normal is also contraindicated, because a rapid drop in blood pressure to normal can produce tissue ischaemia. This may manifest as shock (despite normal to slightly elevated blood pressure values), encephalopathy leading to cerebral injury, retinopathy or optic nerve infarction leading to blindness, hypoventilation and apnoea.