What are the causes and treatment options for orthostatic hypotension?

Causes and Treatment of Orthostatic Hypotension

The most effective management of orthostatic hypotension requires identifying the underlying cause and implementing a combination of non-pharmacological measures first, followed by pharmacological interventions only when necessary, with midodrine being the most evidence-supported medication for symptomatic cases that don't respond to conservative measures. 1

Definition and Diagnosis

Orthostatic hypotension is characterized by:

• Decrease in systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mmHg within three minutes of standing 1, 2
• Symptoms that develop upon standing and are relieved by sitting or lying down 1

Common Causes

Non-neurogenic Causes

• Hypovolemia: Dehydration, blood loss, excessive diuresis
• Cardiovascular: Heart failure, cardiac insufficiency, impaired venous return
• Medications:
  • Antihypertensives (especially vasodilators)
  • Diuretics
  • Antidepressants
  • Alpha-blockers
  • Cardiac glycosides
  • Psychopharmacologic agents
  • Beta-blockers 1, 3

Neurogenic Causes

• Primary autonomic disorders:
  • Multiple system atrophy
  • Pure autonomic failure
• Secondary autonomic disorders:
  • Diabetic autonomic neuropathy
  • Autoimmune disorders
  • Parkinson's disease
  • Vitamin deficiencies (B12)
  • Thyroid dysfunction
  • Paraneoplastic syndromes 1

Treatment Approach

Non-Pharmacological Interventions (First-Line)

1. Fluid and Salt Management:

   • Increased fluid intake (2-3 liters daily)
   • Increased salt intake (6-9g daily) 1

2. Physical Countermeasures:

   • Compression garments (thigh-high with 30-40 mmHg pressure)
   • Abdominal binders
   • Physical counterpressure maneuvers (leg crossing, muscle pumping) 1, 4

3. Positional Modifications:

   • Head-up tilt sleeping (10° elevation)
   • Avoiding rapid position changes 1

4. Dietary Modifications:

   • Small, frequent meals with reduced carbohydrate content
   • Drinking 480 mL of water before standing 1, 4

5. Environmental Management:

   • Maintaining cool environment
   • Appropriate clothing 1

6. Exercise Program:

   • Structured progressive reconditioning
   • Starting with recumbent exercises and gradually progressing to upright exercises 1

Pharmacological Interventions (When Non-Pharmacological Measures Are Insufficient)

1. First-Line Medications:

   • Midodrine: 5-20mg three times daily (with last dose not later than 6 PM)
     • Alpha-1 agonist that increases vascular tone
     • Elevates standing systolic BP by 15-30 mmHg within 1 hour
     • Effect persists for 2-3 hours 1, 3

2. Alternative/Additional Medications:

   • Fludrocortisone: 0.1mg daily for cases with suspected hypovolemia
   • Droxidopa: 100-600mg three times daily for neurogenic orthostatic hypotension
   • Pyridostigmine: 30mg 2-3 times daily for refractory cases
   • Octreotide: For refractory recurrent postprandial or neurogenic orthostatic hypotension
   • Acarbose: For postprandial hypotension, particularly in patients with autonomic dysfunction 1

Special Considerations

Monitoring

• Regular weight assessment and electrolyte monitoring
• Heart rate monitoring during position changes
• Monitor for supine hypertension by measuring BP in both supine and standing positions 1

Population-Specific Considerations

• Elderly: More vulnerable due to age-related changes in autonomic function
• Diabetic patients: Focus on glucose control alongside orthostatic management
• Heart failure patients: Cautious use of volume-expanding agents
• Renal impairment: Start with lower doses of midodrine (2.5 mg) and monitor closely 1, 3

Common Pitfalls to Avoid

1. Focusing on BP numbers rather than symptom improvement
2. Overlooking non-pharmacological measures before starting medications
3. Improper timing of medications (administering vasopressors too close to bedtime)
4. Inadequate monitoring for supine hypertension (all pharmacological treatments can cause or worsen this) 1
5. Using midodrine in patients with urinary retention problems, as it acts on alpha-adrenergic receptors of the bladder neck 3
6. Using midodrine with other vasoconstrictors without careful BP monitoring 3

Treatment Algorithm

1. Identify and address reversible causes (medication adjustment, volume repletion)
2. Implement non-pharmacological measures for all patients
3. If symptoms persist, add pharmacological therapy:
   • Start with midodrine 5mg three times daily (last dose before 6 PM)
   • May increase to 10mg three times daily if needed
   • Consider adding fludrocortisone 0.1mg daily if volume depletion is suspected
4. For refractory cases, consider combination therapy or specialist referral