Synonyms:
a.k.a. postural hypotension
Diagnosis:
Definition:
- Drop in BP >30 mmHg systolic or >10 mmHg diastolic when changing from lying to standing (not sitting), after 2-5 minutes of standing
- Or ≥20 mm Hg (or ≥20%) drop in systolic pressure, either immediately or after 2 min of standing.
- If negative but symptomatic, do orthostatic stress test:
- BP lying & then standing after 12 squats
The normal pulse BP response:
- BP: systolic falls by 5-10 mmHg, diastolic increases by 5-10 mmHg
- Pulse: increases by 10-25 beats/min.
- Pulse:
- If increases >15 beats/min, nonneurogenic causes are suggested.
- If doesn’t increase by >15 beats/min, autonomic dysfunction is suggested
- The reason for the wait 2-5 minute is that the baroreceptor response may be sluggish in the elderly, hence sustained drop in BP on standing is what is looked for in orthostatic hypotension
Postural blood pressure & pulse:
- After ≥5 min in a supine position
- Immediately after standing
- 2 min after standing
- Supine hypertension also suggests autonomic dysfunction
Tilt table testing or formal autonomic nervous system testing can diagnose the condition
Investigations to consider:
Postural BP & pulse
FBC (hematocrit, anemia)
Stool occult blood
U&E
Blood glucose
Syphilis serology (tabes dorsalis)
Physiological & pharmacological autonomic tests
Nerve conduction studies
Tilt table
Autonomic nervous system testing
Treatment:
General measures:
Standing up gradually. Especially in the morning.
Elevate the head of the bed on blocks, 10-20 degrees
Avoid:
- Hot environment
- Valsalva manoeuvre
- High fibre diet +/-Laxatives
If presyncope occurs:
- Squat, lean forward with head between knees
- Leg crossing
- 500-1000ml water ingestion
Diet:
- High salt,
- Small meals, lots of fluids, avoid alcohol.
Shave while sitting
Waist high elasticized support hosiery
Stop offending drugs
Treat underlying cause
Medication:
- Goal is symptom control, not BP control. The risk of complications often out-weighs benefits
- Fludrocortisone P.O. for idiopathic & diabetic cases. Monitor supine BP, K+, heart failure
- Midodrine P.O. Monitor supine BP
- Salt tablets
- Desmopressin intranasally. Monitor Na+ closely.
- Erythropoietin subQ Monitor HCT, Hb, iron stores
- Pyridostigmine P.O.