What is the diagnostic criteria for orthostatic hypotension?

Diagnostic Criteria for Orthostatic Hypotension

Classical orthostatic hypotension is defined as a decrease in systolic blood pressure ≥20 mmHg or diastolic blood pressure ≥10 mmHg within 3 minutes of standing from a supine or sitting position. 1, 2, 3, 4, 5

Types of Orthostatic Hypotension

1. Classical Orthostatic Hypotension

• Occurs immediately upon standing
• Characterized by a "concave" curve pattern of BP decrease
• BP may stabilize at a lower level or continue to decrease during standing 6
• For severe orthostatic hypotension, a fall in systolic BP of ≥30 mmHg may be considered 1

2. Delayed Orthostatic Hypotension

• BP decreases more gradually, not meeting classical OH criteria within the first 3 minutes
• More variable pattern of HR and BP decrease than classical OH
• Variable degree of HR compensation 6

Proper Measurement Technique

1. Initial Position: Measure BP after 5 minutes of rest in supine or sitting position
2. Standing Measurements: Take readings at 1 minute and 3 minutes after standing
3. Equipment: Use a validated and calibrated BP measurement device
4. Arm Selection: Measure BP in both arms initially; if difference >10 mmHg, use the arm with higher BP for subsequent measurements 1

Testing Conditions

• Patient should be fasted for 3 hours before testing
• Avoid nicotine, caffeine, alcohol, or smoking before the test
• Testing environment should be temperature controlled (21-23°C)
• Avoid testing within 2 hours after meals
• Avoid testing after strenuous exercise (within 24 hours)
• Avoid testing during acute illness, fever, dehydration, or marked hyperglycemia 6, 1

Alternative Testing Methods

• Simplified Schellong Test: BP and HR measurements after 5 minutes supine and 3 minutes standing 2
• Head-up Tilt Table Testing: Recommended when:
  • Patient cannot stand safely
  • Clinical suspicion is high despite normal bedside test results
  • Standard orthostatic vital signs are nondiagnostic 2, 3

Clinical Manifestations

Common Symptoms

• Dizziness, lightheadedness
• Visual disturbances
• Weakness, fatigue
• Nausea, palpitations
• Headache

Less Common Symptoms

• Syncope
• Dyspnea, chest pain
• Neck and shoulder pain (coat hanger syndrome) 1, 2, 3

Classification Based on Etiology

Neurogenic OH

• Characterized by inadequate HR increase with standing
• Often shows a concave BP curve pattern
• May present with high supine BP 6
• Associated with autonomic nervous system disorders

Non-neurogenic OH

• Typically shows compensatory HR increase
• Causes include medications, hypovolemia, cardiac insufficiency 5

Clinical Significance

• Associated with increased cardiovascular risk and falls
• Up to 50% increase in relative risk of all-cause mortality 2
• Impaired recovery of BP after standing represents a negative prognostic factor in elderly patients 1
• Both the magnitude of BP change and absolute BP values are important when assessing orthostatic responses 1

Common Pitfalls to Avoid

• Failing to wait the full 3 minutes for proper assessment
• Testing too soon after meals or medication administration
• Not considering the rate of BP recovery, which has important prognostic implications
• Attributing all hypotension to medications without thorough evaluation for other causes
• Assuming fluid responsiveness in all hypotensive patients 1

Proper diagnosis of orthostatic hypotension requires careful attention to measurement technique and recognition of different patterns of BP response to positional change, which is essential for appropriate management and risk assessment.