What is it?

• Mainly elderly (20% 65-plussers)
• = abnormal progressive decrease in BP upon standing (immediate or delayed)
  • ≥ 20mmHg SBP OR
  • ≥ 10 mmHg DBP within 3 minutes OR
  • a decrease in systolic BP to < 90mmHg OR
  • ≥ 30 mmHg in patients with supine HTN (>160 mmHg)
• Due to
  • Low cardiac output OR
  • lack of normal vasoconstriction as a results of chronic impairment of efferent sympathetic activity
    
    

Mechanism

• Low CO due to inadequate venous return
  • Volume depletion
    • Vomiting, haemorrhage, hyperglycaemia, diuretics
  • Venous pooling: e.g. following intensive exercise
• Low SVR due to structural damage to ANS
  • Primary autonomic failure:
    • multiple system atrophy, Parkinson’s
  • Secondary autonomic failure
    • Diabetes
    • Spinal cord injuries
    • Amyloidosis
• Low SVR with a normal ANS
  • drug-induced orthostatic hypotension
    • Alcohol
    • Vasodilators
    • Antidepressants

Prodromal Symptoms

• Upon assuming the upright position
  • Dizziness, light-headedness, pre-syncope
  • Weakness, fatigue, cognitive slowing
  • Visual disturbances
  • Hearing disturbances
  • Pain in the neck and shoulder, angina pectoris (due to ventilation/perfusion mismatching
  • Skin stays WARM

Helpful hints in diagnosis of OH

• After standing up
• Documented hypotension at the event
  • SBP drops at least 20 mmHg
  • DBP drops at least 10 mmHg
  • Or SBP < 90mmHg
• After initiating new medications
• Standing after exertion
• Prolonged standing in hot crowded places
• Worse in morning, with heat exposure or after exertion
• Positive orthostatic testing – stand up test

Treatment