What is orthostatic hypotension?

Definition of Orthostatic Hypotension

Orthostatic hypotension is defined as a sustained decrease in systolic blood pressure ≥20 mmHg and/or diastolic blood pressure ≥10 mmHg within 3 minutes of standing from a supine position. 1

Types of Orthostatic Hypotension

There are three distinct types of orthostatic hypotension:

1. Classical orthostatic hypotension: Sustained decrease in systolic BP ≥20 mmHg and/or diastolic BP ≥10 mmHg within 3 minutes of standing, or a sustained decrease in systolic BP to an absolute value <90 mmHg 1

2. Initial (immediate) orthostatic hypotension: BP decrease >40 mmHg systolic and/or >20 mmHg diastolic within 15 seconds of standing, with spontaneous return to normal within 40 seconds 1

3. Delayed orthostatic hypotension: Sustained reduction of systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg that takes >3 minutes of upright posture to develop 1

Diagnostic Evaluation

Proper measurement technique is crucial for accurate diagnosis:

• Measure BP after 5 minutes in supine position
• Measure again at 1 minute after standing
• Measure again at 3 minutes after standing
• Record both BP and heart rate at each measurement point 1

For suspected delayed orthostatic hypotension, extended monitoring beyond 3 minutes may be necessary, particularly in patients with Parkinson's disease 1.

Clinical Presentation

Common symptoms include:

• Dizziness and lightheadedness
• Visual disturbances
• Weakness and fatigue
• Palpitations and sweating
• Hearing disturbances
• Pain in neck, low back, or precordial region (coat hanger syndrome) 1, 2

Clinical Significance

Orthostatic hypotension is associated with:

• Increased all-cause mortality (up to 50% increase in relative risk) 1, 2
• Increased cardiovascular disease prevalence 1
• Higher risk of falls and syncope 2
• Cognitive impairment 2

Common Causes

Orthostatic hypotension can be classified as:

1. Neurogenic causes:

   • Parkinson's disease
   • Multiple system atrophy
   • Pure autonomic failure
   • Dementia with Lewy bodies
   • Diabetic neuropathy
   • Amyloidosis
   • Spinal cord injuries 1

2. Non-neurogenic causes:

   • Medications (antihypertensives, β-blockers, α-blockers, diuretics, nitrates, antidepressants)
   • Volume depletion/dehydration
   • Prolonged bed rest
   • Advanced age
   • Cardiac insufficiency 3, 4

Management Approach

Treatment goals are to reduce symptoms, improve quality of life, and prevent complications such as falls and syncope 1.

Step 1: Address Reversible Causes

• Review and adjust medications that may exacerbate orthostatic hypotension
• Correct volume depletion
• Treat underlying conditions 1, 2

Step 2: Non-pharmacologic Interventions

• Increased fluid and salt intake
• Compression garments for lower extremities
• Physical counter-maneuvers (leg crossing, squatting)
• Avoiding precipitating factors (hot environments, large meals, alcohol)
• Patient education on symptom management 1

Step 3: Pharmacologic Treatment

For persistent symptoms despite conservative measures:

• Midodrine: FDA-approved for symptomatic orthostatic hypotension; an alpha-1 agonist that increases vascular tone. Typical dose is 10 mg three times daily (with the last dose not later than 6 PM to avoid supine hypertension) 5
• Droxidopa: First-line medication for neurogenic orthostatic hypotension 2
• Fludrocortisone: Effective but has concerning long-term effects 2

Important Considerations and Pitfalls

• Supine hypertension: Midodrine can cause marked elevation of supine BP >200 mmHg systolic; monitor closely 5
• Timing of medication: The last dose of midodrine should not be taken after 6 PM to avoid nighttime supine hypertension 5
• Diagnostic pitfalls: Not monitoring long enough to detect delayed OH, failing to account for supine hypertension, not considering absolute BP level 1
• Medication review: Always perform a thorough medication review as a first-line approach, as many cardiovascular and psychoactive medications can cause or worsen orthostatic hypotension 4
• Balance of treatment: Aim to improve orthostatic hypotension without causing excessive supine hypertension 6

Orthostatic hypotension is a common condition with significant clinical implications for morbidity, mortality, and quality of life, requiring careful diagnosis and a systematic approach to management.