Monday, March 16, 2009

The Importance of Blood Pressure Cuff Size

I've written about blood pressure cuff sizes on my pregnancy website before, but recent comments suggest to me that perhaps it's time I revisit the importance of blood pressure cuff sizes.

So today, we start a small series about the importance of the proper blood pressure cuff size. This is an important issue for fat people of any gender or situation, but it's particularly vital knowledge for fat pregnant women, as we'll explore in a later post.

Why Blood Pressure Cuff Size Is Crucial

The size of your blood pressure cuff is of critical importance in getting proper medical care. If you have your BP taken with the incorrect cuff, the result will be inaccurate and you may get inappropriate treatment.

  • If you use a cuff that is too small, the resulting blood pressure reading will be too high.
  • If you use a cuff that is too large, the resulting blood pressure reading will be too low.

Being off in either direction can have significant health implications.

For example, if they use a too-small cuff (undercuffing) and you are incorrectly diagnosed with high blood pressure as a result, you will be given strong drugs which may have significant negative side effects, yet without any benefits to offset these risks.

On the other hand, if your blood pressure is truly high and goes undiagnosed because they are using a too-large cuff (overcuffing), it can lead to damage to your blood vessels, stroke, and heart attack.

Either way, what is most important is to have ACCURATE data on which to make medical decisions.

Using the wrong cuff size (miscuffing) means that any readings you get are meaningless. Always insist on the correct cuff size before permitting a blood pressure reading.

Miscuffing is Very Common

Research demonstrating the importance of proper cuffing has been around for more than 25 years, yet it remains one of the most common medical mistakes made with people of size.

One classic study on the importance of correct cuffing was Maxwell (Lancet, 1982). This study examined "obese" people already diagnosed with high blood pressure, then re-took their blood pressure with the correct cuff for their arm size. They found that 37%----more than ONE THIRD!----of obese hypertensives were incorrectly diagnosed and actually had normal blood pressure.

Linfors (1984) found twice the level of high blood pressure in "obese" subjects with the standard BP cuff compared to the large adult cuff. Numerous other studies since then have confirmed that using a too-small cuff significantly overestimates blood pressure in "obese" people (sometimes called "Spurious Hypertension").

Of course, cuff size is not just an issue for fat people. A recent study showed that a "standard" cuff often underestimates blood pressure in very lean people; about 80% of the "lean" pregnant women in this study had their blood pressure underestimated with a standard cuff. Thus, many skinny folks may be told that they have normal blood pressure when in fact they have hypertension and are being untreated.

Correct cuff size is an important issue for people of all sizes, but experts agree it is particularly paramount for the "obese."

Typical Cuff Sizes

Do you know what your arm measurement is? You should. Go get a tape measure right now and see what it is. Measure at the mid-point of your arm with a flexible cloth measuring tape.

Once you have measured, memorize that number so you will have it at the tip of your tongue if a cuffing question comes up at an appointment.

If you can, measure it in centimeters because that's how BP cuffs are labeled. However, if you can only measure in inches, click here to help you convert your measurement. (Or do it yourself; multiply by 2.54 to convert inches to cm; divide to go the other way.)

BP cuffs typically come in three sizes--adult, adult large, and "thigh" cuffs.

The adult size is meant for an average-sized adult. The large cuff is meant for people with larger-sized arms (like men with very muscular arms, or "overweight" and "obese" people). The so-called "thigh" cuff is an even larger cuff which is used for supersized people or people who carry a lot of extra weight in their arms.

  • Regular Adult Cuff: 27-34 cm, up to 13.4 inches
  • Adult Large Cuff: 35-44 cm, 13.8 inches to 17.3 inches
  • "Thigh" Cuff: 45-52 cm, 17.7 inches to 20.5 inches

Research differs on exactly when the larger-sized cuff becomes necessary, but the American Academy of Family Physicians states that if the arm circumference is greater than 34 cm (13+ inches or so), a larger cuff size is definitely needed.

Although most fat people will be served by an "Adult Large" cuff, some will need an even bigger cuff. This is the unfortunately-named "thigh" cuff. It's generally used on folks with arms larger than about 17.5 inches or so. Thigh cuff ranges vary a lot, but generally they top out at about 20.5 inches.

What if your arm is larger than that? Never fear, there are cuffs available for you, but they are a special purchase and not likely to be carried by a doctor's office. See below for more information on buying your own specialty cuff or on using forearm measurements instead.

Typical Cuffing Errors

The most common errors in blood pressure cuffing are:

  • Using a regular cuff when a large cuff is needed. This error is extremely common; healthcare workers should know about the importance of this but often ignore it because they don't want to go to the trouble of getting a large cuff or because they don't believe it makes that much difference

  • Using a large cuff for all obese people, even when a thigh cuff is really needed. Unfortunately, many healthcare workers do not know when a thigh cuff is needed

  • Using a thigh cuff for "super-obese" people, even when the upper limits of the thigh cuff are surpassed. Unfortunately, many healthcare workers are not aware of the upper limits of the larger cuffs

If you arm is even remotely borderline, it's very important that you always look at the cuff size range printed on the side of the cuff. If you are not within the range listed or are very close to its upper limits, request a different size and don't let them talk you out of it.

Common Cuffing Questions

What if my arm is close in size to the cutoffs? Which do I use?

One of the most difficult cuffing questions is what to do if your arm measurement is on the borderline between two cuff sizes. In this situation, it is difficult to know which way to err. You don't want to use the larger cuff and miss some hypertension that truly needed treating; on the other hand, you don't want to be treated for something you don't really have either.

Research shows that the error rate begins to increase as you get close to the cuff size cutoffs. Sprafka found that blood pressure cuff sizes made a significant difference in the prevalence of hypertension, even among people who were marginally large and whose arm circumferences were right around the cuff cutoff of about 13 inches. They stated:

Using a cuff one size smaller than appropriate resulted in...[an overestimation of the prevalence of hypertension of] approximately 36%.

Generally sources suggest that you should err on the side of the larger cuff if you are truly borderline because the degree of error is significantly greater when a too-small cuff is used than when a too-large cuff is used.

Do I really need to check the cuff size every time I have my BP checked?

If you need a larger cuff, you need to check that they are using the correct cuff every time you have your BP taken. Never take it for granted, even if they've always done it correctly before.

However, you don't necessarily have to check the range printed on the side of the cuff every single time unless you are near the upper limits of the cuff size. If you are in the middle of the large cuff range, just about all the large cuffs will probably work for you. Just make sure they are using a large cuff.

But if you are borderline it all, it really behooves you to check the range on the cuff. This is because BP cuff sizes are not standardized. Each maker uses its own cutoffs; the numbers listed above are merely general guidelines. Although it's unusual, it is possible to go to one office and need a large cuff, yet need a thigh cuff with the same arm size at another office.

The bottom end of cutoffs for large cuffs (just over 13") tends to be pretty standardized, but the upper end is not. It can vary by quite a bit. Therefore, if you are closer to the upper cutoff between large and thigh cuffs (or at the upper end of the thigh cuff range), you will need to check the cuff sizes printed on the cuff.

Cuff sizes are usually printed right on the side of the cuff (in centimeters, of course). If you know your arm size in cm, you can easily see if you are within the range printed on the cuff. That's why it's so important to memorize your arm size.

What about forearm readings?

In a pinch or in an emergency situation, a regular cuff can be used on your forearm; this will give a general "ballpark" picture of your BP but has not been found to be accurate to the degree really needed for most non-emergent treatment decisions.

Graves (2001) notes that while forearm blood pressure readings are possible, "These readings are not usually performed as falsely higher diastolic blood pressure readings may be obtained."

A Brazilian study (2004) found that forearm blood pressure readings with a standard cuff tended to overestimate BP readings compared to upper arm measurements with an appropriately-sized cuff. Another recent Missouri study (2008) found a similar result.

Singer (1999) found that forearm readings were within 20 mm Hg of upper arm readings in the majority of people, which is not that significant in an emergency situation with non-pregnant people. However, a difference of 20 points can make a lot of difference in treatment decisions in pregnancy, or if a healthcare provider is trying to decide whether or not to put you on high blood pressure medicine when you are borderline.

Therefore, forearm BP readings should be reserved mainly for emergencies in which a BP is needed now, or for supersized folks whose arm size is over 50 cm but who do not have quick access to a specialized cuff.

Generally speaking, forearm readings should not be relied on for regular routine readings or for making non-emergent treatment decisions, nor should they be relied on for decision-making or interventions in pregnancy unless there is a critical emergency.

Buying Consistency: If In Doubt, Get Your Own

Even if you are in the mid-range of the large cuff (which should be routinely available in every medical office or facility), you cannot always count on the doctor's office or even the hospital to have the correct size blood pressure cuff, for it to be in working order, or for medical personnel to be willing to use it. Therefore, you might want to consider purchasing your own blood pressure cuff and taking it with you to each appointment and to the hospital.

"Supersized" people or those with heavy arms may particularly want to invest in their own blood pressure cuffs. While many offices carry large cuffs, not all carry a thigh cuff. If your arm is over 17-18 inches in circumference or you weigh significantly over 300 lbs., you might especially want to consider buying an appropriately-sized cuff of your own.

Undercuffing is chronic in these groups, as few healthcare workers realize when a thigh cuff is required. Sadly, even when they know a thigh cuff is needed, many don't bother to use it, even in very large people.

If your blood pressure is borderline, if your arm is very heavy, or if you are supersized, investing in your own cuff is probably a good idea.

Nowadays, a number of internet companies offer blood pressure cuffs for sale; be sure you only buy one with the correct size cuff for you. Don't just accept that the cuff size is "large;" you need to get the exact range because of the lack of standardized cuff sizing.

In addition, if possible, choose a cuff whose accuracy has been tested and validated. Many monitors out there on the market have not had their accuracy verified. Remember, you want accurate data on which to make your treatment decisions.

The internet company, Amplestuff, sells blood pressure cuffs in varying sizes (including sizes for arms over 20 inches). It is one of the only good sources for the very largest of cuffs. These cuffs attach easily to the blood pressure devices in most offices, and then accuracy is always at your fingertips.

Summary

Blood pressure cuff size is a critical issue in healthcare for people of size, yet despite years of research on the issue, miscuffing is quite common. Some sources suggest that up to 1 in 3 BP readings are miscuffed, and that the "obese" are particularly at risk for miscuffing issues.

If your arm is over about 13 inches, you need to ask about cuff size EVERY time you get your blood pressure taken. Even if the office routinely uses the larger cuff with you, you still need to verify cuff size; don't ever take it for granted that they are using the correct cuff size.

Blood pressure is a very important health issue. If you truly have hypertension, it really does need to be treated. However, these decisions need to be made on the basis of accurate data, and research is very clear that miscuffing is still a significant issue for fat folk.

Coming soon: Your chance to share your BP miscuffing stories, the heightened importance of BP cuff issues during pregnancy, and how to deal proactively with resistance from healthcare workers.

25 comments:

JS said...

Thanks for this very thoughtful and detailed post.

I have one issue to take up, though: You describe the larger cuff as The large cuff is meant for people with larger-sized arms (like men with very muscular arms, or "overweight" and "obese" people).

Actually, many women with very muscular arms have upper-arm measurements greater than 13.4 inches--it's not just muscular men who have issues with the standard-sized adult cuff.

Anonymous said...

great info, thanks very much!!

womantowomancbe said...

Wow -- thanks for this post -- I'd never heard about the different sizes in bp cuffs. I assumed one size fit all (or at least, most), and that they would be accurate regardless of the size of the arm. Ya learn somethin' new every day! :-)

-Kathy

Anonymous said...

Thanks for this! Very informative, and not something I'd ever considered before.

One whole side of my family has very high blood pressure. When I've been measured, mine has always been normal to low. I always chalked that up to the stabilizing influence of the other side of the family. But reading this has made me wonder: is there anything similar that small people can do to make sure that their reading is accurate? Is a regular adult cuff generally the right size even for smaller adults?

Anonymous said...

Would you also be able to provide some information on how tightly the cuff should be wrapped and inflated? I have heard that because a lot of doctors and nurses expect fat people to have high blood pressure, they inflate the cuff to be quite tight, which is not correct for general BP readings and is supposed to be done only when the patient is known to have very high BP (like 170/100).

And are those little cuffs that wrap around the wrist any good? I have also heard they can be quite inaccurate.

LadyGrey said...

There are also child-size cuffs, which I've had to use very rarely on adults (generally people who were wasted from AIDS, or small frail elderly women).

To the last Anonymous: pumping the cuff tighter than necessary is more uncomfortable, but shouldn't affect the accuracy. Unfortunately it's hard to know how high is necessary if a patient is new to you. You need to pump it tighter than you think the actual blood pressure will be, because you measure the blood pressure by listening for the return of the pulse and watching at what pressure that happens. If you guess too low and you hear it immediately, then you have to pump it up again, which is also uncomfortable.

Eema-le said...

For some reason my comment didn't go through. I'm looking forward to reading your next post, because I was miscuffed when I was pregnant, and I'm convinced that it lead to my c-section. At least I'll know more for next time.

sleepless said...

It makes me wonder just how many people are being treated for high blood pressure who don't need to be, even just normal-sized men!

Lindsay said...

JS:

[M]any women with very muscular arms have upper-arm measurements greater than 13.4 inches

Thank you! I've done a lot of weightlifting, and accordingly have an upper arm circumference of maybe 14 or 15". (Not sure, since it's been years since I've measured them). I have an Adult Large cuff at home, but I don't know what size the nurse-midwife at my local women's clinic uses.

I'll have to ask her next time.

Anonymous said...

Great article.

A note to the woman who thought they inflated her cuff too much -- is it possible that you have fibromyalgia? A study showed that a great majority of FMS sufferers experience severe pain when their blood pressure is taken, even when the correct cuff is used and inflated properly.

Although there is also no doubt that overinflation does happen -- I once had a woman take mine who did pump it up too high (I was in literal agony!). She basically rolled her eyes and treated me like #%@%. She also did it twice because she "couldn't hear it the first time." Afterwards, I had severe petichia and bruising all around my arm where the cuff was. I went back and showed her, which she didn't appreciate. But my pressure was much higher than normal when she took it and to me, it's no wonder. Pain and stress make one's B/P go up.

I also wonder this -- if it is so common for medical personel to use the wrong cuff -- what does that do to statistics on obesity/high blood pressure? I wonder how accurate THEY are. Presumedly, in tests they used proper equipment, but I suppose there is no guarantee that they did. I mean, it seems likely that obesity can cause hypertension, but it may not do so nearly as often as doctors think.

Anonymous said...

Is there anything that can be done if having your blood pressure taken is very painful? I'm not sure that anyone is getting an accurate reading on me because I get so stressed when it hurts me so much. I'd appreciate any suggestions !

Dawn said...

Thank you for this. I have actually been bruised by an incorrect cuffsize and appreciate the knowledge.

Zydot ultra clean shampoo said...

Me and my friend were arguing about an issue similar to this! Now I know that I was right. lol! Thanks for the information you post.

Pauline said...

Anon said "I once had a woman take mine who did pump it up too high (I was in literal agony!)...She also did it twice because she "couldn't hear it the first time." Afterwards, I had severe petichia and bruising all around my arm where the cuff was...But my pressure was much higher than normal when she took it and to me, it's no wonder. Pain and stress make one's B/P go up"
That basically describes every bp reading I've ever had done. Now I know it isn't my fault for being fat - I just measured my arm and it's 15" so they should have been using the large adult cuff and they used the regular - I didn't even know there WAS a bigger cuff. The nurses who took my bp should have known better. I'm going to ask for a bigger cuff from now on! I'm just so mad that I've suffered all this time and was always treated like it was my fault for being big, but they were the ones using the wrong equipment! :-(

Anonymous said...

Thankyou so much for this post! I am 24 weeks pregnant with my second child, and had preeclampsia with my first, so my bp is constantly being monitored this time around. The first few times, I could feel that the cuff was too small, and it hurt terribly to have my bp taken. The readings were always around 130/80 or 140/80. Well, this last appointment, the doctor used a slightly larger cuff that actually felt comfortable, and didnt hurt, and what do you know- my bp was 120/80 - much better! I will be insisting on the right size cuff from now on, and am off to do my measurements right now! Thanks again, this post, and the entire site are fantastically and sensitively presented.

Anonymous said...

My last BP reading was really high--but the cuff was extremely tight--and the blood was rushing to my hand making it turn red and puffy with blood. Yet the nurse didn't seem to think that was an issue! I am on BP medications & it was an extremely bad experience and stressful.

Anonymous said...

I wish someone would make all hospitals and doctors offices have all size cuffs, and to educate nurses and doctors on this. It really is an important issue, and it is just unacceptable that they just don't know what they are doing.

Today, I went to the doctor for an ear infection. They took my blood pressure with a "large" cuff. I have very large arms, I need a thigh cuff. The large one squeezes my arm terribly, until I am tensed up from the horrible pain. My reading was like 180/110. I have a wrist monitor at home, and it usually runs anywhere from 120/70, and never know more than 140/85 at the highest.
They asked me if I had taken my medication, I lied and said I had forgotten it in the last 2 days. The truth is, I didn't take it. Because they want me to take 25mg of Atenolol daily. I never took it twice, but even when I took it once a day, the bottom number was dropping to about 50. I felt weak and very strange. I think my bp was going way too low.
They think I have high blood pressure, I think I don't. I have been overweight all my life, and never had high bp until supposedly the last few years.
I tried to tell them about the inaccuracy of bp in people with very large arms due to cuffs that were too small. They all look at me like I'm stupid. The male nurse even told me today, he never heard of that. Then he goes out of the room, and tells the doctor that I am complaining about it. He comes in there and says cuff size has nothing to do with it. He said if anything, it was the shape of my arm. He takes my bp 3 times, with the same "large" cuff, each time putting me in agony. All high readings, so he says it is correct because he took it 3 times. So I get lectured for not taking my bp medication, and for not losing weight.
When I got home, I took my bo with my wrist monitor, it was 140/85.
I have no idea what to do about taking my medication, or what to tell these people. They think I'm crazy. I don't know if i should just take a half of a pill a day, or what. I asked them about bringing my own cuff, and I don't think they are going to allow it.
I'm very upset today, I don't know what to do. Next time, they will probably want to put me in the hospital for high bp.

Well-Rounded Mama said...

Anonymous, you don't mention whether or not you've measured your arm. That's the only way to know what cuff you should be using. You need to know your upper arm circumference in cm, and then you need to know what the "large" cuff serves....some large cuffs go bigger than others. So there's no way for me to know whether or not your dr used the correct cuff of not, and therefore whether that BP was accurate or not.

You need to find a doctor you can trust to take this issue seriously so that you can get accurate data. If your BP is truly being measured with the right cuff and it's that high, then you DO need BP meds. It's no shame to take them; many people (both skinny and not) do. If they are making you feel poorly, then the dose or the type of med needs to be adjusted, but you still need to be on them.

However, you need to MEASURE YOUR ARM and compare it to the range on the cuff the docs are using to see if it's appropriate. If you truly need a thigh cuff, buy your own and bring it to appts. If they won't let you use it, find another practice because it is a BAD practice that won't respond to this concern if you can document that your arm size is not appropriate to their cuff.

BP meds are very VERY important if you truly need them. If your wrist monitor (which is not all that accurate either) is showing a slightly elevated result, then chances are you do need some BP meds....they just may need adjustment for dose or type.

But first things first...measure your arm in cm and compare that to the range that should be posted on the cuff they are using. Then adjust cuffs as needed and you'll get a more accurate reading, and then you can adjust meds as needed.

Don't automatically reject the possibility of needing meds. Get the right data, and then you can adjust medications as needed.

Kate said...

I was in the hospital this past week and I had a variety of people taking my blood pressure, when it was taken with the right size cuff on my upper arm it was fine every time, but they took it with various sized cuffs all over my arm and it just got to the point where I just stopped arguing with them about it. But as I was leaving, the nurse was telling me they've never had a patient with such a large range of blood pressure. I told her that's because it was taken with different sized cuffs from different parts of my arms and not because of me, but she was unmoved.

Then later in the week, my husband was at the doctor and the large cuff in the exam was a very small large cuff, even the doctor said so and acknowlegded that was too small, but that didn't stop him from giving my husband a high blood pressure lecture.

Anonymous said...

I recently went to the doctor and the nurse took my blood pressure. I cannot remember the bottom number but the top was 170. I've only had it at this number when i was having tests or going into emerg. When I stop at the pharmacy it has already dropped 40 points.
Well anyway the cuff got so tight when the nurse took it,rog it seemed to be on so long my fingernails even hurt. Then she let it out so slow. Couldn,t wait for it to get off. Ever since my pressure has been high.
I now have pain in my hand and shoulder. Also a bruise formed on my forearm. Could she have done damage to my arm.

Giulia said...

Okay, I am a "skinny chick".

GP's reading for my BP is something like 11/7 or 12/7.

I could read on her cuff that the cuff she uses for me is a children-adult-adult large cuff.
Means it can accommodate a child, a regular adult and a large adult.

I have a 22cm arm (I am 1.52m for 42 kilos, max 43. No, I don't waste from AIDS nor I am an elderly frail, I am 26 and apart ADHD and Single Sided Deafness, GP says that I am healthy. Eating healthily and in love for exercise).
But amazingly, adult or child cuff, doctors find the same BP reading with me.
Even at my local adult ER, where they use only adult cuffs.

Okay, I live in France.
Maybe the lowest threshold for BP cuffs are lower than the US standards (because the average adult arm size can be smaller in one country than in another).
Or maybe because we can find BP cuffs who can accommodate children and regular adults on the same cuff (I notice that here, many GP have one cuff which can accommodate children and regular adults. It is quite common here).


Do cuff who accommodate children and regular adults on the same cuff exist in the US ?
Or is it something typically French, or European ?


But next time I have a doctor who finds me a BP like 9/4 whereas I feel perfectly fine, I will ask him which cuff he uses. It may save me an unnecessary hospital stay (as high BP can be a side effect of Ritalin I take for ADHD)...


On the other hand, my BP lowered as soon as starting to take Ritalin.

Disclaimer :
Never ever take Ritalin as a weight loss drug
Take Ritalin if it's medically necessary for treating a health issue (ADHD, narcolepsy).

But as Ritalin is not an innocent pill you can take like you would drink water, it must not be taken as a weight loss drug.

Elizabeth Hamilton said...

My mom is in her 90's and has a lot of loose skin which makes use of a cuff a bit of a challenge.

The skin layers or mushes together accordian fashion and the readings are not comfortable at all for her.

How do others handle this when chosing a cuff size?

vesta44 said...

I have been trying to tell the clinic I go to that they're using the wrong size BP cuff, but they insist that the thigh cuff will work. I just measured my upper arm and it's 24", or 61 cm. My BP is always high at the doctor's office (usually something like 145/80 or so) but it's usually 120/70 or less when I take it at home with my wrist cuff (I haven't been able to find a regular cuff that fits my arm). It's also very painful when they take my blood pressure, but I chalked that up to having fibromyalgia (I have cried a few times, it's been so painful).
So the doc insisted that I start BP meds, but lo and behold, when I went back for a check-up 6 wks after starting them, my BP was still in the 140/80 range (can we say too small cuff and pain?). At home, my BP has been running 100/60 or less since I started the BP meds. Now I'm at a loss for what I should do. Should I continue the meds, should I demand another cuff be used, should I try to find my own cuff (that's actually made to fit my arm) and make them use that?

Well-Rounded Mama said...

Vesta, I think I would invest in a cuff made to fit your size. Amplestuff has some. You need accurate numbers on which to make decisions. Take your BP at home with that cuff and also at the dr's office with that same cuff for consistency.

The difference could be White Coat Hypertension (stress from being evaluated), you could be normal at home at that time of day but higher while on the go or at a different time of day, or the wrist cuff may not be that accurate.

Seems to me like the best thing to do is to get a cuff made for your size of arm and use that consistently. Then you'll have accurate data on which to base your medication decisions.

I hope you get some answers soon.

Anonymous said...

I've often wondered why my blood pressure is always higher when my midwife does it (smaller cuff).