How to cope with variation in BP
From Dr Adrian Midgley, Exeter
Dr Rubin Minhas's 10 tips on measuring BP (Clinical, 9 February) tripped my weirdness alarm. BP varies with time of day, OK, well-known. Solution: measure it only at one time of day. Well, no.
Consider blood sugar. Is the suggestion that we should only measure blood sugar at a consistent time of day, to avoid seeing the variation through the day, any more or less sensible? I think not.
On paper records, one could write the time. In electronic records, time is actually captured, although in most current GP systems it is not easily visible.
The 'informatic archetype' for BP includes the time of measurement (along with position, arm, method etc).
Methods of display include presenting all the morning BPs, and all the afternoon BPs, and all the home 0630 BPs (with a 12/7 offset), in such a way as to show whether the allegedly once-daily drugs actually do work that long. (They don't, quite.)
For nerds who want to know far, far more about archetypes, see OpenEHR at www.openehr. org/FAQs/t_archetypes_FAQ.htm