What is the diagnostic approach for orthostatic hypotension in a patient presenting with dizziness?

Diagnosing Orthostatic Hypotension in a Patient with Dizziness

Orthostatic hypotension should be diagnosed when there is a decrease in systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mmHg within 3 minutes of standing compared to the supine position. 1

Proper Measurement Technique

1. Patient preparation:

   • Have the patient rest in supine position for 5 minutes before initial measurement
   • Ensure patient has avoided caffeine, exercise, and smoking for at least 30 minutes
   • Patient should empty bladder before testing
   • Maintain a quiet environment during testing 2

2. Measurement procedure:

   • Measure baseline blood pressure after 5 minutes of lying supine
   • Have patient stand (active standing preferred over tilt-table testing for initial evaluation)
   • Measure blood pressure at 1 minute and 3 minutes after standing
   • Document any symptoms that occur upon standing 1, 2

3. Equipment considerations:

   • Use a validated and calibrated BP measurement device
   • Position cuff at heart level
   • Use appropriate cuff size (bladder should encircle 80% of arm) 2

Types of Orthostatic Hypotension

1. Classical OH: Decrease in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg within 3 minutes of standing 1

2. Initial OH: Decrease in systolic BP >40 mmHg or diastolic BP >20 mmHg within 15 seconds of standing, with rapid return to normal 1

3. Delayed OH: Orthostatic BP drop occurring beyond 3 minutes of standing, characterized by slow progressive decrease in BP 1

Clinical Symptoms to Document

When evaluating Samuel's dizziness, document the presence of:

• Dizziness, light-headedness, weakness, fatigue, lethargy
• Palpitations
• Pallor, sweating, nausea
• Pain in neck/shoulder region (coat hanger pain), low back pain
• Hearing disturbances
• Visual disturbances
• Syncope or near-syncope 1

Note if symptoms:

• Develop upon standing
• Are relieved by sitting or lying down
• Are worse in the morning, with heat exposure, after meals, or after exertion 1

Diagnostic Pitfalls to Avoid

1. Timing error: Failing to measure BP at both 1 and 3 minutes can miss both initial and delayed orthostatic hypotension 1, 3

2. Inadequate rest period: Not allowing sufficient supine rest before baseline measurement can lead to inaccurate results 2

3. Relying solely on symptoms: Orthostatic hypotension can be asymptomatic due to cerebral autoregulation, so BP measurements are essential even without symptoms 4, 5

4. Confusing with POTS: In postural orthostatic tachycardia syndrome, there's a marked HR increase (>30 bpm) without significant BP drop 1

5. Misdiagnosing reflex syncope: In vasovagal syncope, BP drop typically starts several minutes after standing and accelerates, while in classical OH, the drop starts immediately and then rate decreases 1

6. Using interval BP measurements: Continuous BP measurement is preferred for accuracy, as interval measurements have low concordance with continuous measurements in diagnosing OH 3

Additional Diagnostic Considerations

• ECG: Perform to rule out cardiac causes of dizziness, especially if abnormal findings on physical exam 1

• Medication review: Identify medications that may cause or worsen orthostatic hypotension 2

• Autonomic function tests: Consider for persistent cases to pinpoint the lesion in OH, including heart rate response to standing, Valsalva maneuver, and cold pressor test 5

Remember that the primary goal of diagnosis and subsequent treatment should be improving the patient's functional capacity and quality of life, not just normalizing blood pressure numbers 6.