What are the causes and management of orthostatic hypotension?

Orthostatic Hypotension: Etiology and Management

Orthostatic hypotension is predominantly caused by medications, autonomic dysfunction, and volume depletion, with treatment focused on addressing the underlying cause, implementing non-pharmacological measures, and using medications like midodrine when necessary.

Definition and Prevalence

• Orthostatic hypotension is defined as a decrease in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg within 3 minutes of standing 1
• Prevalence ranges from 6% in community-dwelling elderly to 33% in elderly hospital inpatients, accounting for 20-30% of syncope cases in older adults 2

Etiology

Medication-Induced Causes

• Culprit medications are the most common cause of orthostatic hypotension 2
• Common offending medications include:
  • Antihypertensives (particularly alpha-1 blockers, centrally acting agents) 3
  • Diuretics (through volume depletion) 2
  • Psychotropic medications (phenothiazines, tricyclic antidepressants, MAO inhibitors) 3
  • Vasodilators and antianginal drugs 3

Neurogenic Causes

• Primary autonomic failure conditions:
  • Parkinson's disease 2
  • Multiple system atrophy 2
  • Pure autonomic failure 4
• Secondary autonomic dysfunction:
  • Diabetic autonomic neuropathy (cardiovascular autonomic neuropathy or CAN) 2
  • Other peripheral neuropathies 4
  • Neurodegenerative disorders 2

Volume Depletion and Cardiovascular Causes

• Hypovolemia (dehydration, blood loss, excessive diuresis) 4
• Venous pooling (prolonged standing, varicose veins) 4
• Cardiac insufficiency (heart failure, valvular disease) 4
• Age-related baroreceptor dysfunction 5

Clinical Presentation

• Common symptoms include dizziness, lightheadedness, blurred vision, weakness, fatigue 6
• Less common symptoms include syncope, dyspnea, chest pain, and "coat hanger" neck/shoulder pain 1
• May be asymptomatic, particularly in elderly patients 6
• Associated with increased risk of falls, cardiovascular events, and up to 50% increase in all-cause mortality 1

Diagnostic Approach

• Orthostatic vital sign measurement: blood pressure and heart rate after 5 minutes supine and 3 minutes standing 1
• Head-up tilt table testing for patients unable to stand or when clinical suspicion is high despite normal bedside testing 1
• Assessment should include evaluation of:
  • Medication history 2
  • Neurological examination for signs of autonomic dysfunction 2
  • Cardiovascular assessment 2
  • Volume status 2

Management

Non-Pharmacological Approaches (First-Line)

• Discontinuation or modification of culprit medications when possible 2
• Patient education on gradual positional changes and avoiding precipitating factors 2
• Physical countermeasures (leg crossing, squatting, tensing muscles) 2
• Increased fluid and salt intake if not contraindicated 2
• Compression garments for legs and abdomen 2
• Head-up bed position during sleep 2
• Avoidance of large carbohydrate-rich meals 2

Pharmacological Treatment (When Symptoms Persist)

First-Line Medications

• Midodrine (peripheral selective α1-adrenergic agonist) 7

  • Dosing: Individually tailored up to 10 mg 2-4 times daily 2
  • First dose taken before arising, avoid use several hours before bedtime 7
  • Monitor for supine hypertension, which can be severe 7
  • FDA-approved specifically for symptomatic orthostatic hypotension 7

• Fludrocortisone (9-α-fluorohydrocortisone) 2

  • Acts through sodium retention and vessel wall effects 2
  • Initial dose 0.05-0.1 mg daily, titrated to 0.1-0.3 mg daily 2
  • Monitor for supine hypertension, hypokalemia, heart failure, and edema 2

Additional Pharmacological Options

• Erythropoietin (for patients with anemia, Hb <11 g/dL) 2
• Desmopressin acetate (for nocturnal polyuria and morning orthostatic hypotension) 2
• Cardioselective beta-blockers (for CAN-associated resting tachycardia) 2

Special Considerations

• Elderly patients often have supine hypertension alongside orthostatic hypotension, complicating treatment 2
• Diabetic patients should be routinely assessed for orthostatic hypotension, particularly after age 50 2
• Treatment goals should focus on symptom reduction and improving quality of life rather than normalizing blood pressure 5
• Balance the goal of increasing standing blood pressure against the risk of worsening supine hypertension 2

Treatment Algorithm

1. Identify and address reversible causes (medications, volume depletion) 2
2. Implement non-pharmacological measures for all patients 2
3. If symptoms persist, add pharmacological therapy:
   • Start with midodrine if no contraindications exist 7
   • Add or substitute fludrocortisone if response inadequate 2
   • Consider combination therapy for non-responders to monotherapy 2
4. Monitor for supine hypertension and adjust timing of medications accordingly 7
5. For diabetic patients with CAN, consider additional cardiovascular risk reduction strategies 2