Postural hypotension

Postural (orthostatic) hypotension is a sustained fall in blood pressure on standing due to failure of normal cardiovascular compensation. It commonly causes dizziness, visual dimming and falls, especially in older people.

• defined as a sustained fall in blood pressure within 3 minutes of standing of:
• systolic blood pressure of at least 20 mmHg, or
• diastolic blood pressure of at least 10 mmHg
• on standing, venous pooling reduces venous return and cardiac output
• normally this triggers baroreceptor-mediated sympathetic vasoconstriction and a modest rise in heart rate
• postural hypotension occurs when this response is impaired or when intravascular volume is reduced
• an exaggerated rise in heart rate suggests hypovolaemia rather than primary autonomic failure

• hypovolaemia
• dehydration, haemorrhage, vomiting/diarrhoea
• autonomic dysfunction
• diabetes mellitus
• Parkinson's disease and multiple system atrophy
• peripheral neuropathies
• drugs
• diuretics
• antihypertensives, especially alpha-blockers, nitrates and other vasodilators
• levodopa
• tricyclic antidepressants, antipsychotics and sedatives
• alcohol
• prolonged bed rest, frailty and varicose veins may contribute

• dizziness, light-headedness or weakness on standing
• blurred vision, presyncope or syncope
• falls
• symptoms are often worse in the morning, after meals, after exertion or in hot environments

• measure blood pressure lying and after standing for 1 and 3 minutes
• review fluid status and medication history carefully
• look for evidence of autonomic failure, anaemia or underlying neurological disease

• treat the underlying cause
• correct hypovolaemia and review/reduce causative drugs where possible
• advise slow transitions to standing, adequate fluid intake and avoidance of excess alcohol
• compression hosiery and increased salt intake may help if appropriate
• if symptoms persist despite conservative measures, fludrocortisone or midodrine may be used in selected patients