Syncope toolkit: Orthostatic hypotension

Orthostatic hypotension

Orthostatic hypotension is the mechanism of syncope in around 10% of patients.

In this section:

Definitions

Classical OH: a progressive and sustained fall in systolic blood pressure from baseline value greater than or equal to 20 mmHg or diastolic blood pressure greater than or equal to 10 mmHg, or a decrease in systolic blood pressure to less than 90 mmHg which usually occurs within three minutes of standing.

Initial postural hypotension (head rush): blood pressure decrease on standing of more than 40 mmHg systolic blood pressure usually with more than 20 mmHg drop in diastolic blood pressure within 15 seconds of standing. This is a common cause of syncope in young people.

Delayed postural hypotension: blood pressure fall occurs after three minutes (and may occur more than 10 minutes after standing). This is common in the elderly.

Note that the definition of orthostatic hypotension does not state whether the fall in blood pressure should or should not be accompanied by symptoms.

Some patients with chronic orthostatic hypotension can remain conscious despite extraordinarily low blood pressure due to effective cerebral autoregulation.

Orthostatic hypotension can be a chronic, debilitating illness that is associated with reduced quality of life, risk of falls, cognitive impairment and increased mortality. It is common and affects up to 20% of older people living at home and almost one in four older people in long-term care.

Symptoms of orthostatic hypotension

Symptoms include:

Light-headedness
Difficulty thinking
Orthostatic headache
Fatigue, weakness
Nausea
Visual and hearing disturbances (such as black or white dots, greying out, temporary loss of vision, ringing or rushing sounds)
Posterior neck discomfort (coat hanger pain)
Syncope
Recurrent unexplained falls.

Exacerbating factors:

Standing
More severe in the morning
Worse immediately after exercise
High environmental temperature
After meals (post-prandial hypotension)
After prolonged bedrest (deconditioning).

Relieving factors:

Lying down
Less severe or absent when sitting.

Causes of orthostatic hypotension

	Cause
Medication induced (most common cause)	Vasodilators Diuretics Antihypertensives Beta blockers Alpha-adrenoceptor blockers Anti-Parkinson drugs, for example levodopa, ropinerole Tricyclic and non-tricyclic antidepressants Insulin (in diabetic patients with autonomic failure) Narcotics Drugs that induce autonomic neuropathy, for example amiodarone, chemotherapy.
Volume depletion	Haemorrhage (possibly gastro-intestinal) Diarrhoea Vomiting.
Primary autonomic failure	Pure autonomic failure Multisystem atrophy Parkinson’s Disease Lewy Body Dementia.
Secondary autonomic failure	Diabetes Amyloidosis Spinal cord injury Auto-immune autonomic neuropathy Paraneoplastic autonomic neuropathy Renal failure.
Other causes	Adrenal insufficiency Cardiac impairment, such as myocardial infarction, aortic stenosis Vasodilatation, for example fever, sepsis.

See Management of orthostatic hypotension

Orthostatic hypotension

Definitions

Symptoms of orthostatic hypotension

Causes of orthostatic hypotension

Orthostatic hypotension case histories