[The hypertensive crisis in childhood]

Blood pressure, which ist the product of cardiac output and peripheral vascular resistance is regulated by a complex feedback mechanism involving the sympathetic and parasympathetic systems and hormones. An acute disturbance of regulation may lead to a life-threatening increase in blood pressure. Diagnosis is based upon a careful measurement of blood pressure, which must be performed under internationally standardized conditions. Hypertensive crisis refers to a rapid blood pressure increase greater than 30 mmHg above the age-related 95th percentile. The main causes of hypertension in childhood are renal diseases, which may be aggravated by additional conditions either by the clinician himself (e.g. cyclosporin, steroids) or by the patient (lack of compliance). Crisis affects the brain (hypertensive encephalopathy), the heart (left ventricular insufficiency), the retina (visual disturbances) and the mucous membranes (epistaxis). Hypertensive encephalopathy is induced by a break-through of the autoregulation of brain flow, leading to hyperperfusion and, thus to cerebral oedema. The clinical manifestations are characterized by restlessness, severe and diffuse headache, vomiting, nystagmus, impaired vision, dizziness, paraesthesia, seizures and palsies, which may lead - if untreated - to coma and death. The course is usually prolonged and reversible by adequate treatment. The morphological consequences are purpura cerebri, fresh retinal haemorrhages and papillary oedema, apart from left ventricular dilatation and hypertrophy. The diagnostic procedure rests on the quick realization of essential anamnestic (blood pressure, renal disease, drugs), clinical (oedema, cardiac action, central nervous system, fundus) and laboratory parameters (serum creatinine, electrolytes, glucose, blood count, urine). Treatment should start before the manifestation of clinical signs (hypertensive emergency) with rapidly acting antihypertensive drugs.(ABSTRACT TRUNCATED AT 250 WORDS)