Orthostatic hypotension is one of the most consequential findings in geriatric medicine — it explains falls, syncope, fatigue and morning confusion, and it is usually iatrogenic and therefore fixable. It is also one of the most reliably mismeasured. The version done on most wards is a sitting reading, then a standing reading taken as soon as the cuff can be reinflated, and a note that says 'no postural drop'.
Do it properly and it takes four minutes. Lie the patient supine for five minutes first — that is the part always skipped, and without it the supine baseline is falsely low and the drop disappears. Then stand them, not sit them: sitting misses a large proportion of cases. Measure at one minute and again at three, because the two catch different patients, and stay with them, because this is the manoeuvre most likely to reproduce the symptom. A fall of 20 mmHg systolic or 10 mmHg diastolic is the threshold, and any reproduction of the patient's symptoms counts whatever the numbers say. Record the heart rate response too: a drop without a compensatory rise points to autonomic failure or beta blockade, while a large rise suggests volume depletion.
The common false negatives are worth naming. Measuring in the afternoon when the patient's drop is postprandial and in the morning; measuring on a day they have not had their diuretic; measuring after they have been sitting up in the chair for an hour, so they are already accommodated.
When it is positive, the first move is the drug chart, not a prescription. Antihypertensives, alpha blockers for prostatic symptoms, tricyclics, antipsychotics, nitrates, dopaminergic drugs and diuretics — usually in combination, usually accumulated over years, and usually reversible.
- Lie the patient supine for a full five minutes before the baseline reading
- Stand them rather than sitting them, and measure at one minute and at three
- Record the heart rate response alongside the blood pressure, and note any symptoms reproduced
- Treat symptom reproduction as positive even if the fall misses 20/10 mmHg
- Go to the drug chart first when it is positive — antihypertensives, alpha blockers, tricyclics, nitrates and diuretics in combination
Why it matters
A badly measured orthostatic blood pressure produces a reassuring number and leaves a treatable cause of falls in place.
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