Postural hypotension

Question 1

What are the neurogenic causes of postural hypotension?

Answer 1

• T2DM
• Parkinson’s disease
• Small cell lung carcinoma
• Monoclonal gammopathies
• Light chain disease
• Amyloid

Question 2

What are the non-neurogenic causes of postural hypotension?

Answer 2

• Cardiac impairment (MI, aortic stenosis)
• Reduced intravascular volume (dehydration, adrenal insufficiency)
• States that induce vasodilation (inc fever)
• Medications

Question 3

Which medications can cause postural hypotension?

Answer 3

• Diuretics
• Alpha-adrenoceptor blockers
• Antihypertensives
• Insulin
• Levodopa
• TCAs

Question 4

Give examples of diuretics that can cause hypotension/postural hypotension.

Answer 4

Hypotension:

• Furosemide
• Bumetanide

Postural hypotension:
- Bendroflumethiazide (thiazide diuretics)

Question 5

Give examples of alpha-adrenoceptor blockers that can cause hypotension/postural hypotension.

Answer 5

Alpha-1 adrenoceptor blockers:

• Tamsulosin
• Doxazosin
• Prazosin
• Terazosin

Nonselective adrenoceptor blockers:
- Phentolamine

Question 6

Give examples of antihypertensives that can cause hypotension/postural hypotension.

Answer 6

Alpha-1 adrenoceptor blockers:
- Doxazosin

Beta blockers:

• Labetolol
• Carvedilol
• Bucindolol

CCBs:

• Verapamil
• Diltiazem

Question 7

What are the clinical features of postural hypotension?

Answer 7

• Dizziness
• Weakness
• Confusion
• Blurred vision
• Nausea
• Syncope (severe cases)

Question 8

Why are older adults more susceptible to postural hypotension?

Answer 8

• Older adults are more prone to hypovolaemia
• Older adults have decreased baroreflex sensitivity, with impaired a1-adrenergic vasoconstriction and affected HR responses
• Chronic HTN also results in reduced baroreflex sensitivity and LV compliance
• Older have a blunted response to the recruitment of the SNS in BP control
• Polypharmacy

Question 9

What are exacerbating factors of postural hypotension?

Answer 9

• Rising quickly after prolonged sitting or recumbency
• Prolonged motionless standing
• Time of day (early morning after nocturnal diuresis)
• Dehydration
• Physical exertion
• Alcohol intake
• Carbohydrate-heavy meals
• Straining during micturition or defecation
• Fever

Question 10

What is the non-pharmacological management of postural hypotension?

Answer 10

• Avoidance of high-risk situations
• Compression stockings
• Abdominal binders(uncomfortable)
• Counter manoeuvres –> toe raising, leg elevation, leg crossing

Question 11

What is the pharmacological management of postural hypotension?

Answer 11

1. Fludrocortisone
   - Synthetic mineralocorticoid that expands plasma volume
   - contraindicated in heart failure, ascites, chronic renal failure
   - S/E: supine hypertension and severe hypokalaemia
2. Midodrine
   - Vasopressor that is short-acting and can be useful in neurogenic postural hypotension
   - Caution in severe heart failure, urinary retention, underlying hypertension
   - S/E: supine hypertension, scalp paraesthesia
3. Pyridostigmine
   - ACE-I