Measure the standing blood pressure yourself, and measure it late

Lying and standing blood pressure is the most under-performed useful measurement in medicine. It gets delegated, it gets done wrong, and the abnormal result that would have explained the falls is never obtained. Three errors account for most of it. The patient is not lying long enough beforehand — five minutes supine, not thirty seconds on the edge of the couch. The standing reading is taken immediately and then abandoned — the drop that matters often appears at two or three minutes, not at one. And the patient is measured in the morning, fasted, when the postprandial and evening drops that actually cause their falls will never show.

So: five minutes lying, then measure standing at one, two and three minutes, and ask when the symptoms happen. If they fall after lunch, a morning reading tells you little; postprandial hypotension is a separate and common phenomenon in frail older people, and it responds to smaller, lower-carbohydrate meals and to moving antihypertensives away from mealtimes.

And record what you find in a form that survives. 'Postural drop present' vanishes into the notes. '148/78 lying, 112/64 at 3 minutes standing, dizzy' is a number the next clinician can act on, and the one that justifies stopping a drug when the family asks why.

• Five minutes lying before the first reading — the commonest error, and it hides the drop.
• Measure standing at one, two and three minutes; the drop is often late.
• Ask when symptoms occur; postprandial drops need a postprandial measurement.
• Record actual figures and symptoms, not 'postural drop present'.
• Do it yourself in the patient who has fallen; this is not a measurement to delegate and forget.

The statistics, in plain English

The 20 mmHg systolic or 10 mmHg diastolic threshold within three minutes is a consensus definition, not a biological boundary, and a patient who is symptomatic at 18 mmHg has the problem regardless of the cut-off. Because the drop varies with time of day, meals and hydration, a single normal measurement does not exclude orthostatic hypotension — repeating it under the conditions in which the patient actually falls is what makes the test informative.

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