Makindo Medical Notes

💡 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 ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes of standing. ⚠️ Clinical context matters: a fall from 200 → 180 mmHg may be tolerated, but 100 → 80 mmHg can cause collapse.

📖 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.

🧠 Physiology of Standing

• 🩸 ~1 L of blood pools in the legs when upright.
• ↓ Venous return → ↓ cardiac output → ↓ BP.
• Baroreceptors in carotid sinus/aortic arch trigger reflex sympathetic activation.
• Results: ↑ heart rate, ↑ contractility, ↑ vascular tone, plus renin–angiotensin–aldosterone & ADH activation → salt/water retention.
• With age: baroreceptor sensitivity and autonomic response are blunted → higher OH risk.

🩺 Causes

• Peripheral/Autonomic: Diabetes, amyloidosis, nutritional deficiencies.
• Neurological: Parkinson’s disease, multiple system atrophy (MSA), dementia with Lewy bodies.
• Medications: Antihypertensives, nitrates (GTN), diuretics, levodopa, antidepressants, sildenafil.
• Other: Dehydration, Addison’s disease, post-dialysis, idiopathic.

🔎 Classification

• Neurogenic OH:
  • α-synucleinopathies (Parkinson’s, MSA, DLB).
  • Autonomic neuropathy (e.g. diabetic, amyloid).
  • Failure of norepinephrine release → impaired vasoconstriction.
• Cardiogenic OH:
  • Low cardiac output (hypovolaemia, LV dysfunction, pulmonary hypertension).
  • Reduced contractility (amyloidosis, restrictive cardiomyopathy).
• Mixed OH: Combination of autonomic + cardiac impairment.

🧾 Clinical Features

• Lightheadedness, dizziness, weakness, blurred vision.
• Syncope or presyncope on standing.
• ↑ Falls risk and reduced functional independence.

🧪 Investigations

• 🧪 Blood tests: FBC, U&E, calcium (exclude anaemia/electrolyte causes).
• 📉 Orthostatic BP monitoring: Supine & standing readings at 1 & 3 minutes.
• 📊 24h Holter: Rule out arrhythmia or POTS.
• 📡 Implantable loop recorder: Selected cases for unexplained syncope.
• 🧪 Short Synacthen test: If adrenal insufficiency suspected.
• 🫀 Echocardiogram: Exclude AS, HOCM, or other structural heart disease.
• 🪜 Tilt-table test: Assess recurrent syncope / TLOC when diagnosis uncertain.

⚕️ Management

• Medication review: Reduce or stop offending drugs (diuretics, CCB, α-blockers, β-blockers, vasodilators, levodopa).
• Supportive measures:
  • Compression stockings (TEDs).
  • Head-up sleeping position.
  • Increased salt & fluid intake.
  • Caffeine (mild benefit).
• Drug therapy (specialist use):
  • Fludrocortisone (100–200 mcg ON) → expands volume; monitor K⁺, risk of oedema/HTN.
  • Midodrine (2.5–10 mg TDS) → α-agonist; avoid evening doses (night-time hypertension).
• Falls prevention:
  • Pendant alarms, physiotherapy, mobility aids.
  • In severe cases → restrict walking, consider wheelchair support.
• Individualised plan based on underlying cause + frailty context.

📚 References

• The Prevalence of Orthostatic Hypotension: A Systematic Review and Meta-Analysis
• Orthostatic Hypotension: Management of a Complex, but Common, Medical Problem