Cardiovascular

Postural (orthostatic) hypotension

Postural hypotension is a clinically important fall in blood pressure after standing, caused by inadequate compensation for gravitational blood pooling; it presents with postural dizziness, falls or syncope and should trigger medication, volume, cardiovascular, neurological and endocrine assessment.

Definition

Postural (orthostatic) hypotension is a fall in blood pressure after standing that causes or contributes to symptoms such as dizziness, visual disturbance, falls or syncope. NICE uses a systolic fall of at least 20 mmHg or diastolic fall of at least 10 mmHg after standing for at least 1 minute to guide assessment.

First principles

Standing is a normal circulatory stress test

Standing shifts blood into the dependent veins, reducing venous return and stroke volume. The baroreflex normally increases sympathetic vascular tone and heart rate to preserve cerebral perfusion. Postural hypotension occurs when volume, vascular tone, cardiac output or autonomic compensation is insufficient, so symptoms appear during upright posture.

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