Monday, March 26, 2012

Does Your Doctor Know How to Take Your Blood Pressure?

Hard to imagine not, yet....

First there's a brand new study out. I'd tweeted about it when it was released, but thought it was important enough to warrant a blog post.

The study was quite straightforward. Measure the blood pressure in both arms of patients, follow patients for nearly 10 years, and then see if there was any relationship between between arm blood pressure differences and morbidity and mortality.

The results were rather striking, and probably the easiest way to report them is to state that in patients without known cardiovascular disease, having a between arm difference of 10mm Hg or more in their systolic blood pressure (the top number) and having some risk for cardiovascular disease, conferred as much (and perhaps more, but not statistically significantly more) risk to 10 year survival as did having known pre-established cardiovascular disease.

The authors recommend that patients with marked inter-arm differences be managed more aggressively, and while there's not yet data suggesting benefit, it's a compelling study and subsequent to its early publication, I've begun measuring blood pressure bilaterally and have had a few patients who've had large inter-arm variances.

Secondly there's cuff size.

If the cuff's too small, you'll get a falsely high blood pressure reading. Watch your doctor put on the cuff to ensure proper sizing - there's usually a guide on the cuff itself where two parallel lines need to cross to ensure proper fit (you can see them in the picture below). Alternatively when your doctor's putting on the cuff, ask him or her how size is determined!

Lastly there's temper.

If you've been waiting in the waiting room forever and you're upset, it's not impossible your pressure's up as a consequence. I'd hate to see you placed on blood pressure meds because your doctor runs chronically late. If you suspect that your blood pressure's up only when you see your doctor (due to "white coat" or "waiting room" hypertension), consider buying a home blood pressure cuff to monitor on your own. Just bring your home cuff with when you see your doctor so that you can validate your cuff's reading against your doctor's (and they can also check to ensure you're putting it on properly).

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  1. This concerns me because as someone who has lived in an obese body I know the doctor never has a cuff that fits. It literally squeezes you to death and often they can't get a reading. So they will do it again. And then take whatever reading they can get. I have always wondered if they really ever are getting a true reading.

  2. Also, doesn't the height at which the arm is placed have an effect too? In other words, aren't you supposed to rest your arm at heart level and not lower, as is often the case in the doctor's office?

    1. medical student/bankrupt11:56 am

      The arm should be rested on something at heart level. I normally support it on a table or myself. if it is not rested at heart level it will not be accurate, also if the arm is holding itself up, then muscles are contracting and you may well get an elevated reading.

  3. My doctor does run chronically late and my BP is always high when I see her. But last time I went it was the lowest it had ever been with her and she remarked on it. Too which I replied - that's because you're on time! Not sure she saw the funny side.