JUANA SUMMERS, HOST:
Imagine you're at the doctor's office. A cuff is strapped to your arm. You feel a squeeze, and soon you hear two numbers - your blood pressure. But what if that result isn't accurate? NPR's WiIl Stone has more on a new study.
WILL STONE, BYLINE: Think back to the last time your blood pressure was taken. How were you sitting? Where exactly was the cuff? And what specifically was your arm doing?
TAMMY BRADY: People take for granted blood pressure screening and think that it's just simply putting on a cuff and pushing a button.
STONE: That's Dr. Tammy Brady with Johns Hopkins University, who studies how small missteps can distort these numbers.
BRADY: A lot of decisions are made based on what that reading is.
STONE: Previous research shows if the cuff isn't the right size or you cross your legs or you're stressed out, all of that can skew the results. Now, add to the list a relatively common faux pas - holding your arm in the wrong position. Guidelines clearly state your arm should be supported, say, by a desk, and the cuff at about heart level. But Brady says in practice, that's not necessarily what you see.
BRADY: They may have their arm in their lap. They may have their arm on their side.
STONE: Turns out, that really matters. A person's arm resting in their lap could bump up the top number, their systolic pressure, by about 4 millimeters of mercury. The arm dangling at their side could increase it by 6.5. In both scenarios, the bottom number, the diastolic pressure, also gets overestimated. Brady says this artificially high reading could upset patients and even lead to a misdiagnosis of hypertension. For example...
BRADY: If their blood pressure was normally, say, 129, which would be in the elevated range, then that would bring their blood pressure solidly into the hypertensive range.
STONE: So why does this happen? Often, the exam room is not set up properly. Even Brady finds herself rearranging furniture. Also, people are in a hurry. There are competing priorities. Sometimes clinicians don't remember all the steps, some of which are essential.
STEPHEN JURASCHEK: This paper demonstrates that arm position is one of them.
STONE: That's Dr. Stephen Juraschek, at Beth Israel Deaconess Medical Center in Boston.
JURASCHEK: And it's not very complicated, but it does sometimes require some care.
STONE: And the errors can add up. The arm isn't in the right place. The feet are dangling. The patients don't have a moment to catch their breath.
JURASCHEK: And so I've seen people with a net reduction of, like, 20 millimeters mercury. We're talking about a decision to start or not start therapy.
STONE: Juraschek says patients who measure their blood pressure at home would do well to know the correct steps because the pitfalls, like letting your arm dangle at your side or sit in your lap, are the same there as they are at the doctor's office.
Will Stone, NPR News. Transcript provided by NPR, Copyright NPR.
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