Orthostatic Hypotension

Aka: Orthostatic Hypotension, Postural Hypotension, Orthostatic Blood Pressure, Orthostasis, Orthostatic Syncope

1. See Also
   1. Medication Causes of Orthostatic Hypotension
   2. Dizziness
2. Definition
   1. Blood Pressure drop on standing of >20 systolic or 10 diastolic
   2. Occurs within 3 minutes of standing
3. Epidemiology
   1. Common over age 65 years (18%), but only 2% symptomatic
      1. Rutan (1992) Hypertension 19(6 pt 1): 508-19
4. Physiology
   1. Event: Rising from lying to standing position
      1. 300 to 800 ml of blood pools in legs
   2. Physiologic response
      1. Lower extremity Muscle contraction compresses veins
      2. Autonomic response
         1. Baroreceptors in aorta and carotids sense BP change
         2. Sympathetic nervous system response
            1. Increases vascular tone
            2. Increases Heart Rate and cardiac contractility
5. Symptoms
   1. Dizziness or light headedness on standing
6. Causes
   1. Medications
      1. See Medication Causes of Orthostatic Hypotension
   2. Cardiogenic
      1. Myocardial Infarction
      2. Arrhythmia
      3. Aortic Stenosis
      4. Myocarditis
      5. Pericarditis
      6. Bradycardia
   3. Hypovolemia (Tachycardia present, most common)
      1. Dehydration
      2. Hemorrhage
      3. Anemia
      4. Burn Injury
      5. Adrenal Insufficiency
      6. Diabetes Insipidus
      7. Straining
         1. Heavy lifting
         2. Urinating (Micturition Syncope)
   4. Neurogenic Causes
      1. Diabetic Neuropathy
      2. Spinal cord injury
      3. Guillain-Barre Syndrome
      4. Parkinsonism
      5. Tabes Dorsalis
      6. Amyloidosis
      7. Alcohol Abuse
      8. Vitamin B12 Deficiency (Pernicious Anemia)
      9. Syringomyelia
      10. Post-sympathectomy
      11. Human Immunodeficiency Virus (HIV)
      12. Idiopathic Orthostatic Hypotension
      13. Shy-Drager Syndrome
      14. Carotid Sinus Hypersensitivity
          1. Cardioinhibitory Syncope
          2. Vasodepressor Syncope
   5. Venous pooling
      1. Postprandial Hypotension (occurs within 75 minutes of a meal)
      2. Large leg Varices
      3. Prolonged bed rest
      4. Strenuous Exercise
      5. Fever
      6. Sepsis
      7. Heat exposure
      8. Alcohol
   6. Miscellaneous causes
      1. Aging (may be normal over age 70 years)
      2. Hypokalemia
7. Labs
   1. Basic chemistry panel (electrolytes, Renal Function tests, Serum Glucose)
   2. Complete Blood Count
   3. Serum Vitamin B12
   4. Electrocardiogram
   5. Consider morning cortisol level
   6. Consider Holter Monitor
8. Imaging
   1. Head CT or Head MRI
   2. Echocardiogram
9. Diagnosis
   1. See Head-Up Tilt Table Test
   2. Orthostatic Blood Pressure and Pulse
      1. Supine Blood Pressure, pulse after 3 minutes
      2. Standing Blood Pressure, pulse after 3 minutes
      3. Abnormal if Blood Pressure drops >20 systolic or 10 diastolic
   3. Response to 15 second Valsalva maneuver
      1. Normally pressure falls, then rises over baseline
      2. Abnormal if pressure does not overshoot baseline
   4. Pulse variation on deep breathing (sinus arrhythmia)
      1. Normal response
         1. Tachycardia on inspiration
         2. Bradycardia on expiration
      2. Abnormal if <9 beat/min difference during cycle
10. Evaluation
    1. See Head-Up Tilt Table Test
    2. Consider intravascular volume replacement (IV Fluids)
    3. Consider causes above (including medications)
11. Complications
    1. Orthostatic Syncope
12. Management
    1. Avoid medications related to Orthostasis
       1. See Medication Causes of Orthostatic Hypotension
    2. Modify diet
       1. Increase salt
          1. Indicated for 24 hour urinary sodium <170 mmol sodium in 24 hours
          2. Supplement up to 1-2 grams extra-per day (avoid in CHF, edematous states)
       2. Increase water intake (>64 ounces daily)
       3. Avoid Alcohol
       4. Eat smaller, more frequent meals (avoid large carbohydrate rich meals)
    3. Modify activity
       1. Avoid heat exposure or strenuous Exercise
       2. Sleep with head of bed slightly elevated
       3. Rise from bed slowly allowing for equilibration
       4. Avoid standing for long periods of time
       5. Isometric Exercises to work arms, legs and abdominal muscles (e.g. toe raises, thigh contractions, forward flexion at waist)
       6. While standing, move frequently and stand with crossed legs (consider leaning forward)
       7. Avoid work with arms above Shoulder height
       8. Dorsiflex feet several times before standing
       9. Consider Compression stockings
    4. Consider medication therapy
       1. Review precautions before using
       2. Fludrocortisone (Florinef)
          1. Precaution: Monitor for Hypokalemia
          2. Start at 0.1 mg daily, titrate weekly by 0.1 mg to maximum of 1mg daily
          3. Target
             1. Improved symptoms
             2. Significant Edema
             3. Weight gain > 3.6 kg
       3. Midodrine (ProAmitine)
          1. Limit to specialist use (FDA recommends removing from market due to lack efficacy)
          2. Risk of supine Hypertension (mediction should be taken before 6 pm)
          3. Contraindicated in Coronary Artery Disease, Hyperthyroidism, Acute Renal Failure
          4. Start at 2.5 three times daily, titrate weekly by 2.5 mg to maximum dose of 10 mg three times daily
       4. Pyridostigmine (Mestinon)
          1. Start at 30 mg bid to tid and titrate to symptom control or 60 mg three times daily
       5. Erythropoietin has been used if comorbid Anemia
13. References
    1. Engstrom (1997) Am Fam Physician 56(5):1378-84
    2. Lanier (2011) Am Fam Physician 84(5): 527-36
    3. Mathias (1995) Neurology 45:S6-11