Orthostatic Hypotension (Postural Hypotension)
Cardiology (12%) Core Clinical Conditions
1A: Able to diagnose and manage
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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Diagnosis Management
Definition
Orthostatic hypotension (OH), can be defined as low blood pressure that occurs after sitting or standing up. In clinical terms, it is characterised as a fall in systolic blood pressure of 20 mmHg or a fall in diastolic blood pressure of 10 mmHg or more.
This can cause symptoms of dizziness, lightheadedness and, in some cases, cause someone to faint. Generally speaking, these episodes last a few seconds. However, persistent orthostatic hypotension may be an indication of more significant issues.
Aetiology
Dehydration may be brought on by a fever, vomiting, inadequate hydration, severe diarrhoea, and physically demanding activities that cause excessive perspiration. Blood volume reduces with dehydration.
Anaemia
Prolonged bed rest
Use of diuretics
Beta blockers
Antidepressants
Thyroid disorders, adrenal insufficiency and diabetes.
Parkinson's disease, lewy body dementia, amyloidosis etc.
Pathophysiology
Gravity causes blood to accumulate in the legs and abdomen when getting up from a sitting or lying down position. Less blood is returning to the heart, which lowers blood pressure. This causes specialised cells called baroreceptors detect the change in blood pressure and send a signal to the brain. The brain then instructs the heart to beat more quickly and pump more blood, which balances the blood pressure. Additionally, these cells cause blood arteries to narrow and blood pressure to rise.
When something prevents the body from responding to low blood pressure, orthostatic hypotension occurs.
Risk factors
Age: orthostatic hypotension is more common in people 65 and older.
Medications: medications used to treat hypertension such as ACEi, Beta-blockers, calcium channel blockers, diuretics and alpha blockers.
Bed rest: orthostatic hypotension might result from spending a lot of time in bed due to an illness or injury.
Alcohol: alcohol consumption can raise the likelihood of orthostatic hypotension.
Sign and symptoms
Feeling faint
Weakness
Distorted vision
Syncopal episodes or falls
Investigations
FBC
U&E
Hb1ac
Pregnancy test
ECG
Echocardiogram - if appropriate
Diagnosis
A fall in systolic blood pressure of 20 mmHg or a fall in diastolic blood pressure of 10 mmHg or more.
Management
The main goal is to improve quality of life and prevent falls and other causes of OH:
Conservative management:
Lifestyle changes
Good fluid and salt intake
Elimination of triggers such as antidepressants, diuretics and other antihypertensive medications.
Medication management :
Fludrocortisone : off licences use, it increases renal sodium reabsorption therefore increases blood pressure.
Midodrine: causes vasoconstriction which increases the blood pressure.
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