Thursday, September 10, 2009

Blood Pressure

Recently, during my Obstetrics rotation, I saw a woman with very high blood pressure. She was 36 weeks pregnant. I wondered whether her blood pressure was elevated due to the cuff being too small. I asked around, and a few people vaguely remembered that there was once a large cuff but they weren't sure where it was. I eventually found a thigh-sized cuff which gave a much lower reading. It may have been inaccurate too, because the thigh cuffs tend to be too wide for fat arms (unless the fat arms happen to belong to a very tall person).

Nobody else really seemed to think the lack of an appropriate BP cuff was a big deal. I think it's not just a big deal, but totally unacceptable. There needs to be a large cuff available in every ward in every hospital that treats a general adult population. Too-small cuffs directly affect patient care.

Here's a pie-in-the-sky dream: I wish we (the fat acceptance & HAES communities) could raise money to send one-piece large-cuff sphygmomanometers (like the Welch-Allyn DS44-12) to hospitals and clinics, along with a letter discussing the importance of providing appropriate care to large patients!

Edited to add: Thanks to living400lbs for providing the link to Well-Rounded Mama's excellent series about the need for large blood pressure cuffs.


Piffle said...

That sounds like a great idea. I'm not sure how to implement it though.

MamaD said...

I'm a visiting nurse, and I don't always have a large cuff with me when I'm on the road seeing patients. Frankly, I don't really always find them that much more helpful because they're usually wider than a normal cuff, and what I really need is just a longer one. Even when they're the right length, if someone has more of a loose, fatty upper arm (as opposed to a more muscular one), I find the cuff just doesn't seem to fit properly. What I find usually works is to take the BP on the forearm.

Anonymous said...

FYI, Well-Rounded Mama did a series on miscuffing and how wrong-size cuffs and forearm measurements can be significantly off.

Anonymous said...

I am a person who definitely needs the larger cuff. It makes a huge difference in the final reading, and the large cuff honestly fits me better. The regular size cuff actually will EXPLODE OFF MY ARM when it's pumped up.

A larger cuff may not be appropriate for EVERY fat person, but they should at least be available for those who need it.

Bill Fabrey said...

I'm following your blog, and it is excellent. As to the cuff idea, the Welch-Allyn for the Large Adult, is a good idea, except that Large Adult cuffs normally fit arms up to 19" in circumference. That leaves out many millions of people whose arms are larger, although, of course, the actual number is unknown.

For such people, you have to use a thigh cuff, even though it is not just longer, but also has to be wider, to comply with the science behind the test method--which is to correlate air pressure in the cuff to the actual blood pressure in order to determine systolic and diastolic pressures. (It is not a direct measure of actual blood pressure, which is invasive, but is an indirect method.)

In other words, a cuff that is longer but not wider, has not been demonstrated to give good results.

(A cuff that is longer but not wider requires an erroneously high air pressure to cut off blood flow in a fat arm.)

The forearm method works for some people who cannot be measured the conventional way. Some people cannot be measured by either method.

Even though thigh cuffs are a little wider, they can still be used on patients with shorter arms, provided that they hold their arm straight, with no crook in their elbow, and the actual bladder of the cuff can extend a little beyond the elbow, if the outer sleeve of the cuff does not get stretched to its limits, which will give a measurement error.

Many people buy their own large adult or thigh cuff, with or without squeeze bulb and gauge, and take it with them to medical exams.

To determine the right cuff, it is crucial to actually measure the patient's arm. Unfortunately, nobody actually does this. Most practitioners assume that if the cuff fits and doesn't pop off, it must be the right one. Wrong!

More people would use thigh cuffs if they weren't badly named by the industry. They should be called "XL cuffs" or "Extra Large Adult" cuffs. This doesn't happen, probably because everyone is in denial about how many people have arms greater than 19" around! And some folks who need to use that cuff are outraged at the idea of needing a "thigh" cuff.

I am a retired biomedical engineer, and while I'm not a renowned authority on the subject, I've made lots of laboratory measurements over the years using cuffs.

Bill Fabrey

(We sell cuffs to customers with arms up to 35" around. Some can use the XL or the XXL cuffs, and some can't.)

Well-Rounded Mama said...

Thanks for the link to my series on large blood pressure cuffs!! This is SO important, yet miscuffing is sooo common, even today. It seems especially common in obstetrics, alas, but I've had it happen to me both pregnant and non-pregnant.

MamaD, a forearm reading will do for a general ballpark reading if you must have one and don't have the right cuff, but research shows it tends to overestimate BP. (See my FAQ for the research cites.)

Therefore, diagnosis and treatment decisions should generally not be based on forearm readings.

Getting a large cuff and a thigh cuff to take with you on the road would be the most optimal course. If that's not possible, then do the forearm readings but recommend that the patient confirm any problems with the correct-sized cuff at a clinic that has the full spectrum of cuffs.

Bill F, thank you for your insight into the engineering behind cuff sizing. I have one of your large cuffs myself and have also bought them for occasional medical professionals who otherwise might have difficulty affording one in their practice.

I strongly recommend that people measure their own arm size and buy their own correctly-sized cuff to take with them to appts if at all possible. If you can't afford your own cuff, then at least know what size cuff you should be using.

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KellyK said...

I usually remember to ask for the large blood-pressure cuff and haven't had any problem getting it. One thing I've noticed recently, though, is that the automatic blood pressure machines HURT. A lot. Cuff size doesn't seem to matter as much as whether the pressure is being ratcheted up by a machine or by a person. Does anyone with more experience know if there are differences in accuracy between manual and auto?

Michaela A. Null said...

Hi, I am a doctoral student at Purdue University doing a size-acceptance study. I would like to e-mail you more information. If you are interested, please e-mail me at Thank you.

Janie said...

This is a HUGE issue because it leads to so many big moms getting undue c-sections and further complications from said c-section (lower levels of antibiotics than required, incision infection, etc.)
When pregnant I asked my midwife if she had a large cuff because if not I intended to provide my own.

Janie said...
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