Autonomic dysfunction - postural hypotension
Description
- Sustained fall in BP within 3 minutes of standing: >=20 mmHg systolic, or >=10 mmHg diastolic
- Or >=30 systolic if supine hypertension is present
- Variants
- Initial orthostatic hypotension - transient fall >40 systolic within 15 s, resolves by 30 s; needs beat-to-beat monitoring, not a manual cuff
- Delayed orthostatic hypotension - beyond 3 min; often an early marker of degenerative autonomic failure
- Postprandial hypotension - within 2 h of a meal; common and under-recognised in the elderly
- Neurogenic OH - no compensatory rise in heart rate (HR rise <15 bpm, or a ratio of HR change to systolic BP change <0.5)
- Discriminator: does the pulse rise?
- Rises appropriately -> volume depletion, blood loss, drugs
- Does not rise -> neurogenic (autonomic failure), or beta-blockade, or a paced/denervated heart
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