Orthostatic Hypotension
๐ก Note: A symptomatic fall in blood pressure (BP) on standing is common in the elderly.
Orthostatic hypotension (OH) is usually defined as a drop of โฅ20 mmHg systolic or โฅ10 mmHg diastolic within 3 minutes of standing.
โ ๏ธ Clinical context matters: a fall from 200 โ 180 mmHg may be tolerated, but 100 โ 80 mmHg can cause collapse.
๐ About
- Common in older adults; often no single cause is found.
- Increases risk of falls, syncope, cognitive impairment, and mortality.
- Prevalence: ~20% of community-dwelling older adults.
๐ง Physiology of Standing
- ๐ฉธ ~1 L of blood pools in the legs when upright.
- โ Venous return โ โ cardiac output โ โ BP.
- Baroreceptors in carotid sinus/aortic arch trigger reflex sympathetic activation.
- Results: โ heart rate, โ contractility, โ vascular tone, plus reninโangiotensinโaldosterone & ADH activation โ salt/water retention.
- With age: baroreceptor sensitivity and autonomic response are blunted โ higher OH risk.
๐ฉบ Causes
- Peripheral/Autonomic: Diabetes, amyloidosis, nutritional deficiencies.
- Neurological: Parkinsonโs disease, multiple system atrophy (MSA), dementia with Lewy bodies.
- Medications: Antihypertensives, nitrates (GTN), diuretics, levodopa, antidepressants, sildenafil.
- Other: Dehydration, Addisonโs disease, post-dialysis, idiopathic.
๐ Classification
- Neurogenic OH:
- ฮฑ-synucleinopathies (Parkinsonโs, MSA, DLB).
- Autonomic neuropathy (e.g. diabetic, amyloid).
- Failure of norepinephrine release โ impaired vasoconstriction.
- Cardiogenic OH:
- Low cardiac output (hypovolaemia, LV dysfunction, pulmonary hypertension).
- Reduced contractility (amyloidosis, restrictive cardiomyopathy).
- Mixed OH: Combination of autonomic + cardiac impairment.
๐งพ Clinical Features
- Lightheadedness, dizziness, weakness, blurred vision.
- Syncope or presyncope on standing.
- โ Falls risk and reduced functional independence.
๐งช Investigations
- ๐งช Blood tests: FBC, U&E, calcium (exclude anaemia/electrolyte causes).
- ๐ Orthostatic BP monitoring: Supine & standing readings at 1 & 3 minutes.
- ๐ 24h Holter: Rule out arrhythmia or POTS.
- ๐ก Implantable loop recorder: Selected cases for unexplained syncope.
- ๐งช Short Synacthen test: If adrenal insufficiency suspected.
- ๐ซ Echocardiogram: Exclude AS, HOCM, or other structural heart disease.
- ๐ช Tilt-table test: Assess recurrent syncope / TLOC when diagnosis uncertain.
โ๏ธ Management
- Medication review: Reduce or stop offending drugs (diuretics, CCB, ฮฑ-blockers, ฮฒ-blockers, vasodilators, levodopa).
- Supportive measures:
- Compression stockings (TEDs).
- Head-up sleeping position.
- Increased salt & fluid intake.
- Caffeine (mild benefit).
- Drug therapy (specialist use):
- Fludrocortisone (100โ200 mcg ON) โ expands volume; monitor Kโบ, risk of oedema/HTN.
- Midodrine (2.5โ10 mg TDS) โ ฮฑ-agonist; avoid evening doses (night-time hypertension).
- Falls prevention:
- Pendant alarms, physiotherapy, mobility aids.
- In severe cases โ restrict walking, consider wheelchair support.
- Individualised plan based on underlying cause + frailty context.
๐ References
