Postural Hypotension

Question 1

Define postural hypotension

Answer 1

Fall of systolic blood pressure > 20 mmHg

and/or

Fall of diastolic blood pressure > 10mmHg

Fall within three minutes of standing

Question 2

What is another name for postural hypotension

Answer 2

Orthostatic hypotension

Question 3

What is postural hypotension more common in elderly patients

Answer 3

Cerebral autoregulation is responsible for maintaining stable blood flow through the brain. As we age, this becomes less well controlled, causing the brain to become more vulnerable to changes in systemic blood pressure

Question 4

Name some of the causes of postural hypotension

Answer 4

• Older age
• History of neurodegenerative disease e.g. Parkinson’s
• Diabetes
• Hypertension
• Drugs
  
  • Impair sympathetic tone e.g. alpha-blockers e.g. tamsulosin, antihypertensives, diuretics
• Anaemia – via volume depletion
• Chronic dehydration

Question 5

Name some of the drugs associated with causing postural hypotension

Answer 5

Alpha-blockers e.g. tamsulosin

Antihypertensives

Diuretics

Question 6

Describe the pathophysiology of postural hypotension

Answer 6

• When we stand there is about 700 mL of blood pools in the leg veins and the lower abdominal veins.
• Venous return to the heart decreases, resulting in a transient decline in cardiac output.
• To prevent blood pressure from falling there is rapid haemodynamic changes:
  
  • Baroreflex-mediated sympathetic activation – causing an increase in cardiac stroke volume and peripheral vasoconstriction
  • Parasympathetic withdrawal – to increase heart rate
• Failure of these mechanisms causes postural hypotension
• For these mechanisms to function normally, the person must have:
  
  • Normal plasma volume i.e. the person must not be dehydrated
  • Venomotor tone i.e. the ability of blood vessels to respond to these mechanisms

Question 7

What are some of the signs and symptoms of postural hypotension

Answer 7

• Symptoms typically occur on or soon after standing – rare when a person is sitting or lying down
• Presyncope/syncope
• Falls

Question 8

Name some of the aggravating factors for postural hypotension

Answer 8

• These are factors that often make the symptoms worse
• Early in the morning – because of relative volume depletion after overnight fast and pressure diuresis
• Hot environments – because of cutaneous vasodilation
• After meals – because of splanchnic blood pooling
• After standing motionless – because of decreased venous return caused by loss of muscle pump action
• During or after exercise – because of metabolic vasodilation

Question 9

What is the criteria for a diagnosis of postural hypotension

Answer 9

A fall of 20mmHg or more in systolic blood pressure, or a fall of 10mmHg or more in diastolic pressure

Question 10

What is the management options for postural hypotension

Answer 10

• Addressing any underlying pathology
• Discontinuing or reducing the dose of aggravating drugs
• Lifestyle changes e.g. reduce salt intake, compression stockings

Question 11

Name some of the pharmacological agents that can be used to treat postural hypotension if the non-pharmacological approach has not worked

Answer 11

• Volume expansion with mineralocorticoid therapy
• Short-acting vasopressor
• Noradrenaline