wrote:
> Slightly tangential, but in Canada a surprising number of
> patients with hypertension have their own sphygs, with cuffs
> for the upper arm (haven't seen a wrist one here).
>
> In patients in whom I suspect a white coat effect, I
> encourage them to bring their machine to their next visit.
> If it reads pretty much the same as my mercury sphyg (mercury
> tested first to prevent unconscious bias on my
> part) - within 5mmHG - then I agree to use their home
> readings, which are generally quite a bit lower than in the office.
>
> The alternative is for patients to bring in readings from the
> drugstore sphygs which I have decided (arbitrarily) to regard
> as properly calibrated (it being no more or less likely than
> my mercury being accurate). I find the white coat effect to
> be much commoner than perhaps most of us realise, and this is
> a simple way to remove it. It also speeds things up seeing
> those with an established WCE. We just review their own
> figures rather than faffing around with readings of
> questionable use in the office.
>
> FWIW
>
> Jonathan
Calibration of a column of mercury is surely superfluous, since the
standard is millimetres of mercury.
All other methods must surely be calibrated with reference to this -
your mercury sphyg. is accurate by definition!
I've found the electronic sphygs. in our community hospital sometimes
give bizarre results (higher and lower than mercury), but I don't think
any patient's average home readings have ever exceeded the mercury
reading in my consulting room. As the statistics on which BP targets are
recommended are consulting room readings, you're probably not doing your
patients any favours by taking their home readings as Gospel.
--
Michael
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