by Kmom
Copyright © 1996-2003 Kmom@Vireday.Com. All rights reserved.
This FAQ last updated: April 2003
CONTENTS
It is common knowledge that obese people have a higher rate of high blood pressure ("hypertension") than the general population. Every health resource emphasizes this. However, what they often omit is that some fat people are incorrectly diagnosed with high blood pressure when in fact their blood pressure is actually normal! This false diagnosis is usually based on improper use of blood pressure equipment, namely using the wrong sized blood pressure cuffs.
Unfortunately, this is an extremely common mistake, yet there is a great deal of resistance to recognizing the problem in the medical community. Improper use of blood pressure equipment is one of the most common problems a heavy woman faces in her medical care, and this issue becomes even more critical during pregnancy. It is VITALLY important that all women of size become more aware and assertive about correct usage of blood pressure cuffs.
Of course, it is also important to note that not all diagnoses of hypertension are inaccurate. In fact, many diagnoses of hypertension in people of size are accurate, and it is a critical healthcare issue. The point of this FAQ is not that people of size should ignore their blood pressure readings or disregard any diagnosis of hypertension. Not at all! It is that diagnosis of blood pressure problems should be done on the basis of accurate data.
If you have truly have high blood pressure, then that condition needs to be treated, and especially so during pregnancy. This is critical to your health and to the baby's health. But conversely, if you are wrongly diagnosed with high blood pressure in pregnancy, then the medications and interventions that will result can also injure yourself and your baby. It is vital that the correct blood pressure cuff be used for people of size so that a diagnosis of problems can be made on the basis of ACCURATE data.
This FAQ explains the differences between blood pressure cuffs, why a larger cuff is important, helps figure out what size cuff each person needs to use, the importance of being assertive about proper equipment, and how to work with medical personnel to get the most accurate readings. It reviews the research on blood pressure cuff issues, gives resources on where to purchase larger blood pressure cuffs, and relates large women's experiences with blood pressure cuff issues.
Why a Large Blood Pressure Cuff Is Needed
As noted, it is extremely important to make sure your health provider uses the correct size of blood pressure cuff for you. Using a regular cuff on a fat person has been found to artificially inflate blood pressure significantly. If they do not use the correct-sized cuff on you, they will be basing your medical diagnosis and treatment plan on INVALID DATA. It is essential that this number be accurate.
It is particularly critical to have an accurate reading of blood pressure in pregnancy due to concerns about Pre-Eclampsia/Pregnancy-Induced Hypertension (PE/PIH). Outside of pregnancy, a borderline BP number is not pursued as vigorously, but in pregnancy most OBs get very nervous about borderline blood pressures, and will start very aggressive interventions very quickly. Because some cases of PIH progress rapidly to PE and can endanger the baby and the mother, OBs tend to be extremely interventive about borderline blood pressures in pregnancy. Therefore it is extremely important to have accurate data on which to base these critical decisions.
Unfortunately, using the wrong size blood pressure cuff ("miscuffing") is incredibly common. Iyriboz et al. (1994) states:
Using an inappropriate cuff---the most common error in indirect BP measurement---can significantly distort BP readings. This error probably is due to the failure in common practice to measure arm circumference prior to BP measurement. Considering the other common errors committed during BP measurement, together with using the wrong cuff, incorrect measurement of BP is very common.
A classic early blood pressure study (Manning, 1983) agreed. It found that in the group of patients studied who needed a nonstandard-sized cuff, 72% were miscuffed with the wrong size cuff. Almost three-fourths of people who needed a special-sized cuff in that study were miscuffed! Of course, that was years ago and attention to the miscuffing problem has been improved since then, but research shows that miscuffing still happens with appalling regularity.
Miscuffing may be especially prevalent in pregnancy. Anecdotally, many large women report needing to remind staff to get the proper cuff. Many also report significant resistance from some staff to using the larger cuffs. Some staff even refuse outright to use the proper cuff. Obviously, even today, cuff size is still an important issue and should not be taken for granted.
It is important that women of size know what cuff size they should use, check to see that the proper cuff is being used EVERY TIME their blood pressure is checked, and see that their labor support also knows to check on cuff size as well.
Figuring Out What Size Cuff You Need
One of the most difficult issues is knowing what size cuff to use. There are several different adult-sized cuffs and none of the sizes are standardized. If you go to one office, you may need a "large" cuff, but if you go to another office you may need a "thigh" cuff with the same arm. Therefore it is important to know exactly what size your arm is ahead of time and what the general cuff size guidelines are, and then look at EACH cuff being used to see its specific size specifications.
If you depend on your medical personnel to know which is the best cuff size to use, there is no guarantee that they will choose the correct size. Research shows that "undercuffing" (using a BP cuff that is too small for the arm) is one of the most common blood pressure errors and occurs very frequently with obese patients.
Women who are close to average size should be fine with a regular cuff, but most "overweight" people should use a large cuff. However, a lot depends on your arm size. Women with larger arms need the bigger cuffs; if your arms are relatively small you may not need a larger cuff. If you have very heavy arms, you may need a cuff size even bigger than "large."
To know whether you need a larger cuff, measure the circumference of your upper arm. Even if you are sure which size cuff you should use, it is good to know exactly what your arm measures so that if there is ever any question, you'll be able to know which cuff is most appropriate for YOU.
To find out your arm size, measure around the middle of the upper part of your arm, at the midpoint. You may need someone else's assistance to measure accurately. Compare your results to the chart found below.
Be sure to know your arm circumference in both inches and centimeters. Most cuff guidelines are published as centimeters, since this is the measurement system of most of the world. If you only know your measurement in inches, you won't be able to figure out which cuff is best for you, since most guidelines printed on BP cuffs are in centimeters.
Here is a conversion chart (inches to centimeters) of some of the most common arm circumferences in larger women. To convert measurements not on this chart, go to the measurement conversion page of www.sciencemadesimple.com.
Table A - Inches and Centimeter Conversion Chart
| inches | 11.4" | 12.2" | 13" | 13.7" | 15.7" | 16" | 17" | 17.3" | 17.7" | 18.5" | 19.6" | 20.4" |
| centimeters | 29 cm | 31 cm | 33 cm | 35 cm | 40 cm | 41 cm | 43 cm | 44 cm | 45 cm | 47 cm | 50 cm | 52 cm |
Thus if your arm is 16 inches, it is about 41 centimeters. If your arm is 13 inches, the metric equivalent is 33 centimeters. Write down your arm measurement in both inches and centimeters, then put that information someplace safe so that you can double-check it when needed.
Step Two - Discover Whether You Really Need A Larger Cuff
Research differs on exactly when the larger-sized cuff becomes necessary, but the most common rule of thumb is that if the arm circumference is greater than 13 inches (33 cm) or so, a larger cuff size is definitely needed. Although most large people will be served by an "Adult Large" cuff, some will need an even bigger cuff.
For example, the American Association of Family Physicians (AAFP) states:
Accurate measurement of blood pressure requires special consideration. A standard-sized blood pressure cuff should not be used on persons with an upper-arm circumference of more than 34 cm [Kmom note: just over 13 inches]. Large arm cuffs or thigh cuffs can aid in an accurate determination of blood pressure.
Some research indicates that blood pressures taken with a regular cuff begin becoming more inaccurate at about 11.4 inches (29 cm) or so, so a number of studies advocate use of the large cuff at this level. If you are borderline in size, you can have your blood pressure taken with both a regular cuff and a larger cuff; if the two numbers are different by very much, the pressure taken on the larger cuff is the valid one, and the larger cuff should be utilized regularly from then on.
Some medical personnel will tell you that if the cuff can go around your arm, it is an appropriate size for you. This is NOT TRUE and demonstrates a basic lack of understanding of blood pressure cuffs. It is NOT whether the cuff will go around your arm, it is whether the inflatable "bladder" inside the cuff is the appropriate length and width for your arm size. A cuff can go around your arm just fine and still have the wrong-sized "bladder" inside the cuff.
Research is VERY clear that measuring blood pressure with a cuff bladder that is the wrong size artificially alters the blood pressure result. Fit is NOT the correct criteria for whether you are using the appropriately-sized cuff. Length and width of bladder is.
Step Three - Figure Out Which Cuff Size You Need
There are several sizes of large cuffs available, depending on the circumference of your arm:
Most providers carry plenty of 'regular' cuffs plus one or two 'large' cuffs, which should work for most mid-sized fat people. Some providers also carry a 'thigh' cuff, which often works for supersized people or those with heavy arms.
The most common errors in blood pressure cuffing are:
Because cuff sizes are NOT standardized, no absolute size guidelines can be given for each cuff type. However, the American Heart Association has developed general guidelines for cuff sizes. They are summarized in the following table.
Table B* - Cuff Size Guidelines
Acceptable Bladder Dimensions for Arms of Different Sizes**
| Cuff | Arm
Circumference Range at Midpoint (cm) |
Arm Circumference Range at Midpoint (inches) |
| Adult | 27-34 cm | up to 13.38 inches |
| Large Adult | 35-44 cm | 13.7 inches to 17.3 inches |
| Adult thigh Cuff | 45-52 cm | 17.7 inches to 20.4 inches |
is adapted from http://www.americanheart.org/presenter.jhtml?identifier=3000861.)*These guidelines are from a study in the journal, Circulation (1993;88:2460-2467), by Dorothee Perloff,MD; Carlene Grim, MSN, SpDN; John Flack, MD; Edward D. Frohlich, MD; Martha Hill, PhD, RN; Mary McDonald, MSPH, RN; and Bruce Z. Morgenstern, MD, Writing Group. (This table
**There is some overlapping of the recommended range for arm circumferences in order to limit the number of cuffs; the American Heart Association generally recommends that the larger cuff be used (if available) in borderline measurements.
Exact sizing for cuffs is NOT standardized so you can't always depend on knowing that you need a "large" cuff or a "thigh" cuff. Some companies make a large adult cuff that goes much higher than 17.3 inches, while other large adult cuffs tend to run smaller. The only way to know for SURE what cuff you should use is to read the size range printed on the cuff itself. Then you can compare your arm circumference to those guidelines and adjust cuff models as needed. (In older models, the size range may not be printed on the cuff; you may need to read the directions that came with the cuff instead.)
However, it is important not to use a too-large cuff, either. Although research is less clear on this point, there does seem to be some indication that a too-large cuff can artificially register blood pressure as lower than it really is. If your arm size clearly falls into the "large adult cuff" range, don't use a thigh cuff to get an artificially low result.
High blood pressure presents real health risks; if you have high blood pressure (especially in pregnancy) it NEEDS to be treated. Aim for accuracy in measurements and then go from there.
Buying Consistency: Purchasing Your Own Blood Pressure Cuff
Unfortunately, not all providers carry larger cuffs. Sometimes, clinics try to cut costs by not ordering larger cuffs, and cover by telling women that the large cuffs are "out for repair," "broken," or "lost." Other times, larger cuffs are available but medical personnel do not want to go to the trouble of finding them. 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. That way, no one can ever pressure you to "just use the regular cuff." If their large cuff is "not available" for some reason, you have a back-up cuff ready to put to use. Having your own cuff also saves providers the time and bother of trying to find the larger cuffs; they just unscrew the smaller cuff and attach your larger one in its place. Using the same cuff every time also makes for more consistent readings. If a problem ever really does develop with your blood pressure, using the same cuff may help you know it faster and the readings will be more dependable.
Supersized people 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 providers know when a thigh cuff is required. Even fewer use it, even in very large people.
If your blood pressure is borderline, if your arm is heavy, or if you are supersized, investing in your own cuff is probably a good idea. The internet company, Amplestuff, sells blood pressure cuffs in varying sizes (including extremely large sizes). These cuffs attach easily to the blood pressure devices in most offices, and then accuracy is always at your fingertips.
There are 4 blood pressure cuffs available from Amplestuff.
It can be very empowering to have your own perfectly fitting cuff with you at all times and not have to depend on your clinic to have the correct size for you. Although buying your own blood pressure cuff is not cheap, some are reasonably priced. Depending on your situation, they might be an excellent investment for you.
If you are interested in buying your own blood pressure cuff, check out http://amplestuff.safeshopper.com/42/cat42.htm?276. [Kmom is not associated with any company and does not receive any compensation for listing this resource.] Amplestuff also has a portable home blood pressure monitor for sale that can be used with their larger cuffs, although it is uncertain just how accurate any home BP monitor truly is.
Blood Pressure Readings on the Forearm
If there is no large blood pressure cuff available, or if the circumference of a person's arm exceeds the guidelines of the largest blood pressure cuff available, it is possible to take a blood pressure reading on a person's forearm (Singer, 1999). This technique is sometimes used on people who are extremely large in an emergency when there is no thigh cuff available or if the thigh cuff is too small for the person's arm. (Many thigh cuffs are accurate only to about 20 inches.)
However, the validity of forearm blood pressure measurement is questionable. Providers must be cautious about relying on forearm measurements, as the results may not be accurate. For example, the journal American Family Physician, writing in its article, "Medical Care for Obese Patients: Advice for Health Care Professionals," states:
If the upper arm circumference exceeds 50 cm [19.6 inches], the American Heart Association recommendations suggest using a cuff on the forearm and feeling for the appearance of the radial pulse at the wrist to estimate systolic blood pressure. The recommendations note that the accuracy of forearm measurement has not been validated.
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." Singer (1999) found that readings were within 20 mm Hg 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.
If a blood pressure is truly needed (like in an emergency situation) and there are no other options, a forearm measurement can offer an approximate idea of what a person's blood pressure is likely to be. Since many extremely obese people have blood pressure issues and this can lead to significant health problems, forearm BPs remain an option if no other choice exists. Better to have some idea of a person's blood pressure than none at all.
However, forearm readings are not an adequate substitute for proper equipment under normal circumstances. There are other options that should be pursued instead whenever possible. For example, some "thigh" cuffs are available now that are accurate for arm sizes above 20 inches. In addition, as noted above, www.amplestuff.com sells blood pressure cuffs that are accurate for extremely large arms, up to 35 inches in circumference. So there are better alternatives available than forearm blood pressure readings.
If your arm is significantly larger than 16-17 inches or so, you may want to purchase your own blood pressure cuff so that you do not have to worry whether your provider has a large enough cuff. If your arm size is over 20 inches, you should definitely consider buying your own properly-sized cuff because your provider is unlikely to carry a cuff appropriate for your arm.
Because forearm blood pressure readings are not validated to be accurate and because high blood pressure in pregnancy leads to so many interventions, forearm blood pressure readings should not be used in pregnancy except in unusual emergency situations where no other options are available. Otherwise, the proper sized cuff should be purchased and used consistently.
Either work with your provider to have them purchase the proper cuff for you, or you buy the cuff for them with the understanding that you will receive a partial discount on your prenatal bills. However, the best choice of all may be to buy your own and take it with you to every appointment and to the hospital.
Other Blood Pressure Measurement Devices
Home blood pressure monitors are often recommended when a woman's BP is borderline or starting to rise. It is also used when "White Coat Hypertension" is suspected. What about these other blood pressure measurement devices? How accurate are they in general? How accurate are they for people of size? And especially, how accurate are they for pregnant women of size?
White Coat Hypertension is said to occur when women have high blood pressure at the doctor's office but normal blood pressure at other times. Anxiety and stress may falsely elevate blood pressure in a medical setting in some people. This is a very real phenomenon. Research has recognized that it results in much unnecessary intervention and high cesarean rates.
In an well-meaning effort to distinguish between those women who truly are experiencing high blood pressure in pregnancy and those who are simply victims of White Coat Hypertension, some doctors send women home with home blood pressure monitors, or tell them to go to their local pharmacy and take their blood pressure there. This is an excellent idea in principle, but may fail in practice because home blood pressure monitors tend to be inaccurate in general, and especially so for people of size.
Blood pressure devices set up for passers-by in pharmacies and medical supply stores almost never have large cuffs, let alone thigh cuffs, and are rarely accurate for people of size. Don't use them.
Most blood pressure kits sold in pharmacies contain only the regular size blood pressure cuff. However, rarely is this fact noted on the package. Research has shown that even those home BP monitors that are designed for "obese arms" may not have actually been validated as being accurate for obese arms. Generally speaking, it is not a good idea to buy a home BP kit from pharmacies if you are a large person.
Other home blood pressure devices measure blood pressure at the wrist or on your finger. Because the size difference is less at these areas than it is in the upper arms, some medical professionals have speculated that these may be more accurate for people of size. However, research shows that they are not very reliably accurate in people of ANY size and should be used with great caution, if at all.
Schwartz (1996) found that NONE of the portable automatic blood pressure home monitors for obese arms available at the time of that study were accurate in large pregnant women. They checked arm, wrist, and finger BP readings, and found that wrist and finger readings were quite unreliable. Arm readings were more accurate, but still varied quite a bit----less than half of the arm readings on the portable device were within 5 points of the patient's true blood pressure. That kind of pinpoint accuracy is needed in pregnancy, so these portable BP kits were not considered a great choice.
Schwartz et al. concluded:
If any elevation in blood pressure was measured in the clinic, these women would not benefit from self blood pressure monitoring because of inaccuracies in measurements obtained from the commercially available devices described [in the study]. We were unable to find any other devices that could be evaluated for obese patients with large arms. Until an accurate device is developed, the interpretation and management of hypertension in the obese gravida will continue to be a problem."
Therefore, caution must be used in making diagnoses based on readings (good or not) taken outside of the office. Unless a new device has been invented since the Schwartz study (and tested as being accurate for larger women by independent researchers), the data being provided by these portable home devices may be invalid. Treat any readings from home BP monitors with caution.
Amplestuff ( www.amplestuff.com ) does have a home blood pressure monitor available for sale for less than $40. However, it only comes with a standard cuff and a larger cuff must be ordered along with the BP kit. It is not known if this particular kit has been validated as being accurate in larger people, but if you must get a home blood pressure device, this is probably a better choice than one you would get at your local pharmacy. But again, treat the results with caution.
Does Blood Pressure Cuff Size Really Make That Much Difference
Many health care workers question whether a larger blood pressure cuff really makes that much difference. Medical research repeatedly documents that it does. For example, The American Heart Association states:
A longer and wider cuff is needed for adequate compression of the brachial artery in the obese patient with a very large upper arm...The error of overestimating the pressure when measuring with a cuff that is too small for an obese arm can be considerable and can lead to misclassification of an individual as hypertensive and to unnecessary concern and therapy.
One classic study on the importance of correct cuffing was Maxwell et al (1982). This study examined obese people already diagnosed with hypertension, then re-took their blood pressure with the correct cuff for their arm circumference. They found that 37%----more than ONE THIRD!----of obese hypertensives were incorrectly diagnosed and actually had normal blood pressure.
Graves (2001) reviews research from other studies on "miscuffing" and the errors it leads to. He cites research that showed that in large patients (Body Mass Index >34), "Subjects were 2.2 times more like[ly] to be classified as hypertensive and 1.4 times more likely to be classified as borderline hypertensive when the standard cuff was used to measure blood pressure compared with when the classification was based on the more appropriately sized large adult or thigh cuff."
Sprafka (1991) 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 found that "Using a cuff one size smaller than appropriate resulted in...[an overestimation of the prevalence of hypertension of] approximately 36%." Even if your arm is not very heavy and is borderline for needing a larger cuff, having the correct cuff makes a difference!
In the section on "Women's Stories" below, several women experienced much higher blood pressures with a too-small blood pressure cuff, and in some cases, this almost led to significant intervention and harm. For example, some big moms have nearly been forced into a premature cesarean because of a blood pressure taken with the wrong cuff.
I came within an hour of having an emergency c/s at week 33 with my son. They even went as far to have the surgical resident (who would be assisting my regular OB) and the anesthesiologist speak with me. They were just waiting for my regular OB to get to the hospital and see me before they prepped me.
When he did come in and see me, the first thing he did was take my BP. When he reached for the BP cuff, he said, "Is this the cuff they're using to check your pressure with?" I said yes, then he went out and yelled up one side and down the other to the nursing staff about jeopardizing his patient and baby because they didn't use the large cuff. It made a huge difference! The readings went from [about] 180/104 to [about] 114/63. [Normal is <140/90.....Kmom] Surgery cancelled!
Usually I'm much more alert than that and demand the large cuff. I had requested it several times in the hospital and the nurses kept saying it didn't matter...[even after delivery] the jerks still wanted to use the small cuff!!!
Having gone through two pregnancies with elevated BP, it became kind of crucial to me to have it done correctly. When I was pregnant with [my daughter], I would have it done at my OB/GYN office, and have it either normal or slightly elevated. Then I would get to my perinatologist's office and have it skyrocketed.
The first issue was the cuff, until I insisted I get the right sized cuff (my OB didn't even own one, but I made sure the girl ran next door to borrow one from another doctor for each of my visits). The perinatologist didn't have one and was the only doctor in the building....
Twice [the perinatologist] suggested my OB take [my daughter] by c-section immediately due to high BP. Thank gosh my OB relied more on his own records than on the recommendation of the peri....
Some women have inappropriately been treated with blood pressure medications when their blood pressure was actually normal, exposing them to all the significant side effects and potential harm of the medications unnecessarily. In What Every Pregnant Woman Should Know, Dr. Tom Brewer notes that there have been a number of cases of pre-eclampsia/toxemia diagnosed in obese women due to using the wrong size cuff.
Kmom is very aware of cuff size issues because she has experienced repeated problems with miscuffing over the years. She once had the experience of having her blood pressure taken with a "regular" blood pressure cuff, then the proper larger cuff. Using a too-small cuff resulted in a false BP elevation of more than 50 points! Additionally, in her first labor, an incorrect blood pressure taken with a "regular" cuff nearly resulted in extreme amounts of intervention when her pressure was actually normal. Having the correct cuff really does make a lot of difference.
Although extensive research documenting the importance of using the correct-sized blood pressure cuff in obese people has been around for more than 20 years, using the wrong cuff is still one of the most common medical errors made with people of size. And since the threshold of treatment and intervention for borderline or high blood pressure is so much lower in pregnancy, it is ESPECIALLY important that the correct cuff be used on pregnant women of size so that treatment decisions can be based on truly accurate data.
Other Factors That Affect Blood Pressure Readings
There are many factors besides cuff size that can affect blood pressure readings. For example, many nurses take blood pressure with improper technique. This has also been documented to affect blood pressure readings.
These subtle variations in technique don't cause huge differences in BP readings, and a few points of error probably wouldn't matter that much if you have very normal blood pressure. But if your blood pressure tends to be borderline at all, even small errors could make a critical difference. Again, this is especially true in pregnancy where the threshold of intervention for borderline blood pressure is very low.
Therefore, you will want to pay close attention to your nurse's blood pressure technique. Be polite and nice but insistent on the correct technique if you notice problems. Be prepared for some resistance if you point out errors. If your nurse is not cooperative or is rude about the problem, be sure to write a letter of complaint to the doctor or head nurse. They need to know if improper medical technique is affecting patient care.
To take a person's blood pressure accurately, the patient should be:
The person taking the blood pressure should:
According to a WebMD interview with Charlene Grim, RN (chairwoman of the American Heart Association Committee that reviewed the current blood pressure guidelines), taking a person's blood pressure when seated on the exam table with no back support can raise blood pressure by 10 points. Not an earth-shaking amount, but one that can buy a lot of intervention if your blood pressure is borderline already.
Similarly, Terent and Breig-Asberg (1994) found that taking the blood pressure with the arm at the side of the chest instead of supported at the level of the heart raised blood pressure by about 10 points as well. [Note that this is the average difference and that some differences may actually be quite a bit greater than 10 points.]
Netea et al. (1999) found that the common practice of having the patient rest her arms on the arm-rests of the chair also resulted in falsely elevated blood pressure values. Along with sitting with legs dangling and no back support, taking blood pressure with arms at the wrong level is probably one of the most common technique errors found.
Although they should know better, sometimes nurses will also try to take blood pressure over a person's clothes. This is also improper technique. You can help by wearing clothes to your appointments that have sleeves that are short and loose or are easy to push up. If this is not possible, you can insist on taking your arm out of your sleeve before the blood pressure reading. You should do this even if they try to tell you it's not necessary. It can make a difference.
Krass et al. (1988) also found that many family doctors did not regularly calibrate their blood pressure devices, which can also lead to significant errors. As noted above, the device should be pointing exactly to zero before beginning; if it does not, then it is introducing significant error into the readings. As a patient it is not up to you to schedule calibration maintenance on BP devices, but you can take a moment to notice if the device is pointing exactly to zero before you start.
Finally, the nurse should not pump the blood pressure cuff up too high at the beginning of the blood pressure measurement, because this can result in what Kugler (1994) termed "cuff inflation hypertension." This can be a problem for plus-sized women, because medical personnel often assume that all heavy people have high blood pressure and accordingly pump the cuff up quite high at the start. If you know that you have normal blood pressure, you can request that the nurse not pump the cuff up excessively. If they need convincing, tell them it hurts. That way, you get a more comfortable and more accurate blood pressure reading.
Although these differences in blood pressure measurement technique may seem awfully picky, research does show that they can result in inaccurate blood pressure readings. Even a small elevation in blood pressure of 10 points or so can make a difference in treatment near the end of pregnancy when doctors really watch for Pregnancy-Induced Hypertension and Pre-Eclampsia.
Because doctors often expect heavy women to have high blood pressure in pregnancy, they tend to have a VERY low threshold for intervention in obese women at the end of pregnancy. Even a vaguely borderline blood pressure reading can result in early induction with some doctors, and that often leads to a giant cascade of problems.
Therefore, although being so careful about blood pressure technique can seem overly picky, it probably is very important for big moms to be aware of these issues and be proactive about them.
Dealing with Obstinate Medical Personnel
Although other errors in technique can falsely raise blood pressure, the most common source of errors by far is undercuffing. While many doctors and nurses will respond positively to a request for the correct cuff, large women do report very strong resistance and even hostility from some medical personnel. People of size need to know how to respond proactively and firmly if this issue arises.
Reasons for Resistance To Using the Correct Cuff Size
When the research on the importance of cuff size is so clear, why is miscuffing still such a common occurrence? And why is there such resistance to getting the proper cuff?
Reasons vary. Sometimes, there are simply no larger cuffs available because administrators won't pay for them, a decision which puts the health care worker in a difficult spot. They may feel greatly pressured by administrators or insurance rules to get blood pressure readings on all patients despite the lack of proper cuffs, and so may pressure you to go ahead with the wrong cuff just to get some numbers down "for the record."
The problem may also be that larger cuffs are not stored conveniently, and workers have to waste precious time and energy going through storage areas to locate bigger cuffs. Nurses are chronically understaffed and as a result are often pressed for time. They face a lot of pressure to get their paperwork done quickly, and having to take time out to get the larger cuff may seem like a frustrating waste of time to them.
Sometimes, medical personnel resist getting larger cuffs because they don't want to go to any extra effort. They may view the larger patient with hostility anyhow, seeing them as causing extra trouble, and so may resist doing anything "extra" for them at all. They may think privately that all fat people have hypertension anyhow, so what difference would getting a big cuff make? Size bias can unfortunately play a role in miscuffing too.
But most often, resistance to using large cuffs is based on a misunderstanding of cuff size issues. Linfors (1984) listed a number of blood pressure cuff myths held by many medical personnel, such as:
However, Linfors refuted all of these myths. The study showed that using the standard cuff in patients with large arms gave falsely high prevalences of high blood pressure and borderline high blood pressure. In fact, in the study, "The prevalences of high blood pressure and borderline high blood pressure were twofold greater with the standard cuff than with the large adult or thigh cuffs in obese patients."
While there can be many reasons why large blood pressure cuffs are not used more often, lack of conveniently available larger cuffs and myths about cuff sizes are probably the most prevalent. However, while we can understand why it happens, that does not mean we should excuse it when it happens. Change will only come when we insist on it and refuse to accept anything less.
Strategies Health Care Workers Employ to Resist Using the Proper Cuff Size
Despite the research and education programs for health care workers about blood pressure cuff sizes, resistance persists. There are many different strategies health care workers have been known to employ to avoid using the correct cuff, including:
None of these excuses are legitimate or acceptable. The correct cuff must be used, without exception, or the blood pressure reading should not occur. Period.
Dealing with Resistance Proactively
Most of the time, if you inform personnel of the medical research about cuff size and remain firm about getting the correct cuff, health care workers will work with you to meet your needs. Most genuinely care about patients and want to give appropriate care. A little education goes a long way.
Even when there is more resistance, however, there is usually no need for the situation to become unpleasant. You don't have to be discourteous, just politely FIRM that the correct equipment is vital to the accuracy of the data and you will accept nothing less. You simply politely refuse testing until the correct cuff is brought, or ask them to move on to other tests until the correct cuff becomes available.
However, once in a while, people of size will run into more stubborn and even rude medical personnel. In some cases, people of size have been bullied into using the wrong cuff, or harassed when they refused a reading with the wrong cuff. Should you encounter a situation like this, keep in mind that YOU HAVE THE RIGHT TO REFUSE ANY MEDICAL TEST OR TREATMENT. Legally, they cannot force you to do anything against your will.
Using the legal phrase, "I do not consent," helps medical personnel realize you are serious about the need for the correct cuff. You may also need to remind them that you have the right to refuse testing. Occasionally, they may ask you to sign a waiver that you are refusing a test "against medical advice," but you always have the right to refuse medical testing or treatment.
None of this has to be confrontational. You can be polite but firm. Reassure personnel that you are not completely refusing to have your blood pressure taken, only refusing to have it taken with improper equipment that may result in false readings. Tell them you would be happy to have your blood pressure taken when they can do it with the correct equipment. Trying to keep things as civil as possible may help your needs get met, but don't mistake politeness for lack of resolve. Stay firm that you MUST have the proper cuff size and that there is no room for compromise there.
If necessary, ask to see the health care worker's supervisor and request another nurse for your care. This is usually pretty easy at a hospital. Although most patients don't realize it, you can request a different nurse in the hospital if you have problems with one particular nurse, and it usually is not that difficult to get a new nurse assigned to you. This can often help resolve problems when health care workers are not attentive to your needs as a large person.
If you have a hard time advocating for yourself, ask to see a Patient Advocate. Every hospital has one. Tell them that you have concerns about your needs getting met as a person of size. Share with them the importance of using a large blood pressure cuff, and about resistance you have met. The job of the Patient Advocate is to help represent your views and needs and to advocate for them. Because they have a recognized voice and role within the institution, they often have a great deal of influence and may be able to get needs met that might otherwise get ignored.
Some large women may feel guilty about being assertive like this. After all, women are often raised with the idea that "good girls" are always polite, always please others, and never complain. As fat women, we are often taught that we don't deserve good treatment, that our needs and desires don't matter, and that it's not our place to question medical authorities. Some women have been taught to be too embarrassed by the size of their arms to draw attention to them by demanding the right cuff.
But think about it. They are asking you to take a test with improper equipment, the results of which could ultimately result in harm to you or your baby (see L's Story and Anna's Story). You are completely within your rights to refuse testing under these circumstances, and it is completely reasonable to complain if medical personnel are not responsive to your concerns. If you feel uneasy about being assertive about this issue, remember that your baby is depending on you to stand up for him. Women who have trouble advocating for themselves are often able to overcome that hesitancy when they realize they are really advocating for their babies.
Don't feel that improper blood pressure technique is too trivial to complain about; if personnel are using incorrect technique or equipment to take blood pressure, sooner or later someone is going to be harmed by that. The mistake needs to be pointed out and corrected. You are doing yourself and your baby a favor by insisting on correct equipment, and you are doing a favor for every big mom and baby who comes after you. Step up to the plate and be ready to act when needed.
Writing a Letter of Complaint
If you have had a real problem with a nurse or other medical personnel taking your blood pressure incorrectly or bullying you into using the wrong size of cuff, be sure to write a letter to the doctor or institution. Be polite but quite upfront about the problem. One helpful technique is to document the proper guidelines for blood pressure, and to suggest that perhaps their medical personnel are in need of an additional training program on blood pressure technique. This usually catches administrators' attention!
Providing documentation for your concerns lends your complaint more legitimacy. Kmom has prepared a short handout, documenting the American Heart Association's Guidelines for Blood Pressure Cuff Sizes, plus summaries of several studies supporting the importance of correct blood pressure cuff sizes. You may print this out for use with your doctor or health care insurance organization. Attaching this handout to a letter of complaint may help the complaint to be taken more seriously.
Be sure to send your letter to a person in authority, i.e. your doctor, the head nurse on the obstetrical unit, the nurse manager, a hospital administrator, other doctors from your clinic, etc. Also send a copy to insurance representatives. Then watch how quickly they respond! Complaints that are channeled to "higher-ups" often receive swift and positive solutions to the problem.
Conclusion
Many women on "big mom" email lists report having their blood pressures measured with the wrong-sized cuff. It is shocking that despite 20+ years of research showing the importance of using an appropriate cuff size, it is STILL very common for medical personnel to use the wrong cuff, to insist that it doesn't make much difference, or to hassle people who insist that the correct equipment be used.
You must practice being constantly assertive in your care on this most basic issue. Fat people need to be VERY vigilant about using the correct cuff size. Don't ever let them bully you into using the wrong cuff. Be sure your labor support people also know to monitor for correct cuff size.
Many nurses and doctors are not aware of the differences in blood pressure with different-sized cuffs, so it's up to you to be proactive and educate them. Sometimes you may have to be quite assertive---be prepared. Think ahead of how you would respond if this issue came up during your prenatal care or during your birth.
Research is VERY clear that using a too-small cuff on a large arm artificially inflates blood pressure readings. Because of this, all doctors and hospitals should have at least 3 different sizes of adult cuffs: the "standard" cuff, the "adult large" cuff, and the "thigh" cuff. They should also know when and how to use these cuffs properly.
However, reality often does not measure up to these standards. Larger cuffs are drastically underused. Many doctors and hospitals do not even carry larger cuffs. Even when they do, the larger cuffs may not be readily available, health care workers may not understand the need for larger cuffs, or workers may not be willing to use them. In real life, blood pressure cuffs are often used inappropriately, and especially in women of size.
This is even more of a problem in pregnancy, when even minor elevations in blood pressure can lead to major interventions. Because doctors expect fat women to have high blood pressure in pregnancy, their threshold for intervention is quite low in this population. Even a very small "rise" in blood pressure at the end of pregnancy in a heavy woman may result in drastic interventions and dangerous medications. Thus, it is even more critical that big moms become vigilant and uncompromising about blood pressure cuff size.
Don't just trust that health care workers will use the proper cuff when taking your blood pressure. Although doctors and nurses should know better, research clearly shows that miscuffing is common, even today. In populations with special arm sizes, a high percentage of patients are miscuffed, resulting in a significant problems in diagnosis and treatment.
Therefore, as a woman of size, you need to learn to be proactive on this issue. Know your own arm measurement, both in inches and in centimeters. Know which cuff size YOUR arm needs. If you need a special blood pressure cuff, consider buying one of your own so you will always have it. Take it with you to every doctor appointment and to the hospital as well.
Be sure to ask the nurse whether a large-sized cuff is being used EVERY time your blood pressure is taken. Do not take for granted that they will use the correct cuff on you, even if this is the same nurse that has always taken your blood pressure before. Nurses are incredibly overworked and often are forgetful of details like these. Many women have found that when they forget to ask, that is when the incorrect readings tend to happen. ASK EVERY TIME YOUR BLOOD PRESSURE IS TAKEN.
Also be sure your labor support team is aware of the importance of a larger cuff size, that they know your arm size and which cuff size you need, and that they ask about cuff size EVERY time a BP is taken during labor. If a high BP reading occurs, have them ask the nurses to double-check the cuff size being used. During labor you will be too busy to properly monitor cuff size; make sure your labor support team is prepared to do it for you.
Some health care workers will try to tell you that a regular cuff is sufficient. It is not. If your provider does not have a large cuff or dismisses the need for one, you need to have an alternate plan of action. Do NOT let them bully you into using the regular-sized cuff.
You should also realize that resistance to using the correct cuff is a strong signal that this is not a size-friendly doctor or clinic. They do not practice responsible medicine if they try to pressure people into inaccurate testing, or let their staff do so. Try complaining to see if the problem is a minor glitch, quickly taken care of. If you do not receive a satisfactory response, strongly consider switching practices. If you do not have the option to switch because of insurance or financial issues, consider buying your own cuff from Amplestuff (see below) and taking it with you to every appointment and to the hospital.
In addition, don't hesitate to complain if you were treated poorly by personnel or if they pressured you inappropriately. Part of your job as a mother is to become an advocate for yourself and your child. Self-assertive treatment starts HERE, with the basics.
Many fat people let themselves be pushed around or treated rudely by medical personnel. It's time we started fighting back. Don't EVER put up with less-than-stellar treatment. If necessary, find an advocate to help you stand up for proper treatment and respectful care.
It is crucial that heavy women not be misdiagnosed with hypertension that they do not have. On the other hand, if you do have high blood pressure, you absolutely need it diagnosed and treated properly, as it can present significant risks to both mother and baby. Therefore, correct blood pressure technique is an issue of critical importance to women of size.
Play it smart---insist on the correct blood pressure cuff size and proper technique so that you can get proper care based on accurate readings.
I came within an hour of having an emergency c/s at week 33 with my son. They even went as far to have the surgical resident (who would be assisting my regular OB) and the anesthesiologist speak with me. They were just waiting for my regular OB to get to the hospital and see me before they prepped me.
When he did come in and see me, the first thing he did was take my BP. When he reached for the BP cuff, he said, "Is this the cuff they're using to check your pressure with?" I said yes, then he went out and yelled up one side and down the other to the nursing staff about jeopardizing his patient and baby because they didn't use the large cuff. It made a huge difference! The readings went from [about] 180/104 to [about] 114/63. [Normal is <140/90.....Kmom] Surgery cancelled!
Usually I'm much more alert than that and demand the large cuff. I had requested it several times in the hospital and the nurses kept saying it didn't matter...[even after delivery] the jerks still wanted to use the small cuff!!!
Having gone through two pregnancies with elevated BP, it became kind of crucial to me to have it done correctly. When I was pregnant with [my daughter], I would have it done at my OB/GYN office, and have it either normal or slightly elevated. Then I would get to my perinatologist's office and have it skyrocketed. The first issue was the cuff---until I insisted I get the right sized cuff (my OB didn't even own one, but I made sure the girl ran next door to borrow one from another doctor for each of my visits---the peri didn't have one and was the only doctor in the building).
The second thing was my OB always had me either sit in a chair and not speak while they did it, or they did it with me lying down. The peri always did it...on the exam table, legs dangling, no back support, while they were chatting with me. Finally, upon the recommendation of the peri, I got a unit for home. From that point on, I refused to let the peri's office do it. I would do it myself while I was out in the car, and bring them my reading.
Twice they suggested my OB take [my daughter] by c-section immediately due to high BP. Thank gosh my OB relied more on his own records than on the recommendation of the peri.
Oh, and I had to fight with the insurance company to get a large-sized cuff for my home unit.
S's Story: (*taken from the book, Women Afraid to Eat by Frances M. Berg)
[One] doctor...had me on a high blood pressure medication unnecessarily for three years. It was a new doctor who used the proper blood pressure cuff and said, 'What are you doing on medication? Your blood pressure is low!'
Kmom's stories:
Story #1: When in the hospital laboring with my first baby, my BP was taken with what I assumed to be a large cuff, and it came back pretty high (my pressure is usually fine). They started to get me ready for all kinds of invasive interventions.
I asked for a new reading with a large cuff. However, I really had to be assertive to get the second reading; the nurse at first said a larger cuff wasn't important, then that they didn't have a large cuff, and then she told me it was lost. I had to really get insistent before she went and searched down the bigger cuff. To their surprise, this reading was quite a bit lower--back in a normal range. The interventions got cancelled and I went back to laboring. To think I almost didn't check on the cuff size because I was in the middle of labor and was concentrating on other things! This shows how important it is to be aware of cuff size at all times! (Or to have a doula or partner who can monitor for this for you.)
Very few staff members during that hospital stay were aware of the difference a large cuff made, and many of them resisted the idea of going and getting one. Even when they were willing to look for one, the nurses often had trouble finding a true large cuff, despite being in a hospital setting where they should be plentiful. The resistance to using the correct-sized cuff was obviously quite considerable, both on an individual basis and on an institutional basis.
However, in this case getting the correct cuff made the difference between very intense medication/intervention and being considered in the normal range and left alone. If I had not protested and gotten another reading, I would have pushed into a TON of intervention that I didn't need.
Story #2: In my second pregnancy, I had to fight this problem again. The nurses at my providers' offices were great, although I ALWAYS check to be sure the correct cuff is used. However, after the baby was born, I had a nurse come in to check my blood pressure postpartum. I routinely asked about whether she had a large cuff, and she argued with me that it wasn't necessary. She snottily asked what kind of medical training I had to insist on this, and really resisted getting the other cuff. I refused to let her take the reading without the large cuff. She huffed off and got it.
All the rest of the nurses during that stay were fine and did not complain about getting the larger cuff, but all it takes is one falsely high reading to get you into a whole lot of unneeded intervention. Just goes to show that you must ALWAYS ask about the cuff issue, even in the middle of the night when you are tired or concentrating on coping with labor. Be sure your labor coaches know to check on this too.
Story #3: In my third pregnancy, my midwife did not even own a large-sized blood pressure cuff. However, when I pointed out their importance, she was happy to buy one, and I never had any other problems with it that pregnancy, probably because most of my prenatal care was done outside of the usual institutional settings. However, if I had not informed her of the importance of the correct-sized cuff, she would have used the regular cuff and my BP would probably have come back artificially high.
Story #4: Even outside of pregnancy, I find lots of resistance to using a larger cuff. Even at my own doctor's family practice, where I have had many discussions about correct cuff size and blood pressure measurement technique, the nurses still sometimes use the wrong cuff and improper technique.
One week the nurse wanted to use the wrong cuff, and I spent some time explaining to her the importance of the larger cuff. She agreed it was important and got the larger cuff. A few days later I was back for a follow-up appointment, and the same nurse did the preliminary work. I thought about asking her if she was using the correct cuff but did not, since we'd just had the big discussion about it. When she began taking my blood pressure, however, I could tell she had used the wrong cuff. I asked her about it and sure enough, she'd automatically used the small cuff, DESPITE our extensive discussion of the situation one week earlier! You just can't trust that they'll remember on their own.
Story #5: Another time I was very ill with bronchitis and went to an Urgent Care Clinic. The nurse there tried to take my blood pressure with the regular-sized cuff. I stopped her and requested the large cuff. She informed me that their large cuff was broken and "out for repair." [Interestingly enough, it had been 'out for repair' the last time I was at that clinic too.] I refused a reading with the small cuff. She offered to do it on my forearm, but since this has not been validated as accurate, I also refused that. It is our RIGHT as patients to refuse any tests or treatments, and I chose to exercise that right since my blood pressure was not vital to my illness and they did not have the correct equipment to do the test properly.
The next thing I knew a male nurse very aggressively barged into the room, told me that they had done experiments in the E.R.. and the large cuff only made about 6 points difference in readings, and he was going to do a reading with the small cuff. I refused, and cited research studies and personal stories that it could indeed make a LOT more difference than that. He was not happy.
Then he got tricky. He suggested that we try an experiment to see what the difference actually was. He asked me what my BP usually ran, and then wanted to measure my BP with the small cuff to see if it indeed ran higher. I foolishly thought this was a good way to show him how much difference it could make, so I agreed.
The reading with the small cuff was 188/88, VERY high. He shook his head and left the room, seeming to acknowledge that it indeed did make a difference. Only later did I realize that he probably went out and wrote down that falsely high BP reading in my chart----that he had TRICKED me into a reading with a small cuff under the guise of scientific experimentation! He didn't care that it was wrong; he just wanted to get a reading, ANY reading. I was furious and wrote the clinic a scathing letter.
I then had my BP taken with the correct cuff at a follow-up appointment at my regular doctor's office, and it was 130/80--higher than usual for me but still in the normal range. Using the correct cuff made a difference of more than FIFTY points in my blood pressure. Imagine if I had been pregnant and had gotten a reading like that without knowing that it was incorrect! I could easily have ended up on potentially harmful medication, or been pressured towards an early induction or cesarean, as "L" was in the story below.
Question asked on the Big Mom's email list: "Did the nurses at the doctor's office and/or hospital automatically use the larger cuff for you?" [This shows the variation in response from health care providers--some good, some not.]
M.L.: I did sometimes have to remind the nurses to use the large cuff, but I think that's because they didn't always realize I needed it.
Aramanth: Yes, every time without fail. In fact, it was marked on my notes to always use the large cuff.
Shari's Story: They used a large cuff. Don't remember any problems with that.
D.K.: Not always. I had to make sure each time that they were using the larger cuff. If it was my 'regular' person taking BP, it would always be larger, but anyone else I'd check up on.
C.M.'s Story: Yes, always without a problem.
Lj: Only after having to remind them several times. Eventually they had the large cuff waiting for me in the exam room.
M.E.: At the doctor's office, yes, all the time without being reminded. At the hospital in [Labor and Delivery], no. The first nurse used the larger cuff and she even had to go search for one but did so. Then she left it in my room for when she came back. Sometime the next day someone removed it and the day nurse said she didn't need to use the large cuff. (Too lazy to look for it in my opinion.)
Resources For Buying Large Blood Pressure Cuffs
The following resources may have blood pressure cuffs for larger-sized people. There are probably others around as well; if you know of a resource that is not listed here, please email Kmom with details.
Amplestuff
There are 4 cuffs available. Economy Cuffs run about $40. Size L is for 13"-19" circumference arms, and size XL is for 17"-26" arms. Deluxe cuffs are MUCH more expensive (like $120!) but these are tapered to fit better, have 'stays' to help keep shape on very large arms, and tend to be more comfortable for the super-sized. The Deluxe Cuffs come in size XL for arms from 17"-26" and size XXL, for arms from 26"-35".
Medical Supply Stores
Check your phone directory to see if there is a medical supply store in your area. They often carry (or are able to order) large blood pressure cuffs, and these may be less expensive than from other resources. However, there are a number of different sizes of cuffs, so be sure you ask about sizing, and the quality of cuff in the very large sizes may not be as reliable. READ THE LABELS to be sure what size arms the cuff is most appropriate for; if the cuff just says "large adult" without specifying an exact size range, don't buy it.
Books
What Every Pregnant Woman Should Know. Brewer, Gail Sforza and Brewer, Tom. Revised Edition. New York: Penguin Books, 1985.
Classic book that discusses how doctors in the past actually caused many cases of pre-eclampsia in women by using diuretics and restricting protein, calories and salt in pregnant women. These doctors were trying to prevent pre-eclampsia (toxemia) by trying to prevent its symptoms, but they often ended up causing the very problem they were trying to avoid. In the book, Brewer notes, "Obese women are often incorrectly diagnosed as hypertensive when a standard-size blood pressure cuff is used to take a reading. When the cuff is too small, additional pressure on the mother's arm reads on the meter as elevated blood pressure. Using a larger cuff prevents this error."
Women Afraid To Eat:Breaking Free in Today's Weight-Obsessed World. Frances M. Berg. Hettinger, North Dakota: Healthy Weight Network. 2001. Available from www.healthyweight.net and www.amplestuff.com.
Websites
Medical Journal Articles About Blood Pressure Cuff Sizes
Aylett, M et al. Evaluation of Normal and Large Sphygmomanometer Cuffs Using the Omron 705CP. J Hum Hypertens. Feb. 2001. 15(2):131-4.
"We recommend that large cuffs should be used for all patients with an arm circumference of 28 cm or above." [Kmom note: 28 cm equals about 11 inches.]
Feher, MD et al. Fat Arms, Obesity and Choice of Blood Pressure Cuff
Size in Diabetic Patients. Br J Clin Pract. Nov-Dec 1995.
49(6):286-7.
Found that in their diabetic clinic, research showed most patients with a BMI > or = 25 were "likely to require an alternative adult BP cuff [i.e. a large cuff--kmom] if their blood pressure is to be measured precisely." Used an arm circumference cutoff of 29 cm (11.4 inches) for needing a larger cuff.
Graves, JW. Prevalence of Blood Pressure Cuff Sizes in a Referral Practice of 430 Consecutive Adult Hypertensives. Blood Press Monit. Feb 2001. 6(1):17-20.
"Overestimation of blood pressure by using an inappropriately small cuff has been well documented....Health care settings such as the emergency department or outpatient clinics where hypertensive patients are encountered should have easy access to both large and standard adult cuffs." Recommends 33 cm (13") as cutoff for using a large cuff, and notes that 61% of hypertensives in this study had an arm circumference >33 cm ad needed the large cuff. Also notes, "Beginning at an arm circumference >29 cm, and with increasing inaccuracy as arm circumference increases, the standard cuff increasingly overestimates blood pressure."
Guagnano, MT et al. What is the Real Prevalence of Hypertension in Obesity? Recenti Prog Med. Jul-Aug 1995. 86(7-8):306-11.
"The use, in the obese patient of inappropriate cuffs...contribute significantly to the overestimation with the inclusion of false positives even in relevant percentages."
Guagnano, MT et al. Many Factors Can Affect the Prevalence of Hypertension in Obese Patients: Role of Cuff Size and Type of Obesity. Panminerva Med. March 1998. 40(1):22-7.
Found that when the correct large-sized cuff was used, the prevalence of hypertension was "strikingly lower" in
overweight and obese women, compared to when the regular-sized cuff was used. Also investigated the role of type of obesity in hypertension; basically, apple shapes were much more likely to have true hypertension than pear shapes (53% vs. 29%).
Iyriboz, Y et al. Agreement Between Large and Small Cuffs in Sphygmomanometry: A Quantitative Assessment. J Clin Monit. March 1994. 10(2):127-33.
"Arm circumference plays an important role in determining proper cuff size for BP measurement. The small cuff overestimates BP in patients with large arm circumferences (>29 cm), which represents more than 75% of the U.S. adult population. However, measurements of BP with the large cuff are not significantly different from those of small cuff measurements in subjects with small arm circumferences (< or =29 cm). Therefore, we propose that the large cuff be used for routine BP measurement of the adults in the United States." Later on, the authors state, "In conclusion, using an inappropriate cuff---the most common error in indirect BP measurement---can significantly distort BP readings. This error probably is due to the failure in common practice to measure arm circumference prior to BP measurement. Considering the other common errors committed during BP measurement, together with using the wrong cuff, incorrect measurement of BP is very common."
Linfors, EW et al. Spurious Hypertension in the Obese Patient. Effect of Sphygmomanometer Cuff Size on Prevalence of Hypertension. Arch Intern Med. July 1984. 144(7):1482-5.
Listed common BP cuff myths held by many medical personnel, such as arm circumference not being important in assessing BP, that errors would occur only in the very obese, that BP changes only minimally as long as the BP cuff encircles the arm, etc. "The prevalences of high blood pressure and borderline high blood pressure were twofold greater with the standard cuff than with the large adult or thigh cuffs in obese patients (arm circumference greater than or equal to 35 cm [13.7 inches] or body mass index greater than or equal to 34 or weight greater than or equal to 95 kg [209 lbs.]. Routine use of the large adult cuff will provide accurate BP measurement and avoid unneeded evaluation and treatment."
Manning, DM et al. Miscuffing: Inappropriate Blood Pressure Cuff Application. Circulation. October 1983. 68(4):763-6.
Studied nurses and doctors taking 200 blood pressure readings in 167 people to see how well personnel followed the cuff size recommendations of the American Heart Association. Found that miscuffing occurred 32% of the time in the overall population. Doctors were not more accurate than nurses; 63% of doctors used the proper cuff size while 69% of nurses used the proper cuff sizes. Of the subgroup of patients that required a non-standard cuff size (both extra-small or extra-large), 72% were miscuffed! Study also notes that the manufacturer's cuff size guidelines printed on the cuffs differed significantly from the American Heart Association guidelines, and that relabeling of cuff sizes needed to take place.
Maxwell, MH et al. Error in Blood-Pressure Measurement Due to Incorrect Cuff Size in Obese Patients. Lancet. July 3, 1982. 2(8288):33-6.
Classic study that found that 37% of obese "hypertensives" were actually normotensive, and had been misdiagnosed because the wrong-sized cuff was used. They recommended the following cutoffs for arm size/cuff size: <33 cm (13 inches) = regular cuff; 33-41 cm (13-16 inches) = large cuff; and >41 cm (>16 inches) = thigh cuff. Also has a fascinating 'conversion' table for correction of blood pressures taken with different sized cuffs.
O'Brien, E. Review: A Century of Confusion; Which Bladder for Accurate Blood Pressure Measurement? J Human Hypertens. September 1996. 10(9):565-72.
"The use of cuffs containing inappropriate bladders is a serious source of error which must inevitably lead to
incorrect diagnosis in practice, and erroneous conclusions in hypertension research. There is unequivocal evidence that either too narrow or too short a bladder (undercuffing) will cause overestimation of BP...A detailed review of the literature permits a definitive statement on bladder dimensions for a given arm circumference and clearly indicates that substantial error is caused by the use of inappropriate cuffs."
Perloff, D et al. Circulation. 1993;88:2460-2467. Available at www.americanheart.org.
American Heart Association Guidelines for blood pressure measurement. See Table B above.
Prineas, RJ. Measurement of Blood Pressure in the Obese. Ann Epidemiol. May 1991. 1(4):321-36.
"There is a need for caution in measuring blood pressure in the obese. Problems related to adequate cuff-bladder size and shape are apparent from a review of the literature...The most important adjustment for measuring blood pressure in the obese derives from choosing the correct cuff width-arm circumference ratio...Past studies probably overestimated blood pressure level in the obese and so underestimated the risk of elevated blood pressure in the obese."
Schwartz, WJ et al. Blood Pressure Monitoring During Pregnancy. Accuracy of Portable Devices Designed for Obese Patients. J Reprod Med. August 1996. 41(8):581-5.
The accuracy of automatic home bp devices designed for obese women was tested. None of the women had chronic hypertension or Pregnancy-Induced Hypertension. Finger devices, Wrist devices, and Arm Cuffs (traditional) were used. Readings were off by as much as 6-21 points, depending on the device. Less than half of the readings were within 5 points of true BP even in the most accurate of the devices (the arm cuff). "If any elevation in blood pressure was measured in the clinic, these women would not benefit from self blood pressure monitoring because of inaccuracies in measurements obtained from the commercially available devices described [in the study]. We were unable to find any other devices that could be evaluated for obese patients with large arms. Until an accurate device is developed, the interpretation and management of hypertension in the obese gravida will continue to be a problem." Notes that there are studies checking the accuracy of self-BP devices in average-sized people, but none in non-pregnant heavy adults with large arms. The accuracy of home devices must be questioned.
Singer, AJ et al. Comparison of Forearm and Upper Arm Blood Pressures. Prehosp Emerg Care. Apr-Jun 1999. 3(2):123-6.
Study for emergency medical workers about the use of forearm blood pressure when a patient has too large an arm for the cuffs they have with them. Compared BPs from the forearm to those from the upper arm in patients to evaluate how well forearm BP can substitute for standard BP. 151 patients were studied. They found that "Forearm BP is a fairly good predictor of standard upper arm BP in most patients. Forearm BP may be used when measurement of upper arm BP is not feasible." They do note that the differences between forearm and upper arm measurements were within 20 mm Hg in most patients; it is important to realize that while 20 mm Hg may not seem like a huge difference in an emergency setting in a non-pregnant patient, it can make a lot of difference in pregnancy intervention decisions. Forearm BP is appropriately used when there is no other way to take a BP correctly, in order to get a general idea of what a patient's BP is. However, it should not be used unless there is no other option. It is not an adequate substitute for proper equipment.
Sprafka, JM et al. The Effect of Cuff Size on Blood Pressure Measurements in Adults. Epidemiology. May 1991. 2(3):214-7.
Studied 181 adults of all ages, mostly of arm circumferences up to 34 cm (just over 13 inches, the cutoff for absolutely requiring a large cuff). Took the blood pressure of each person with a small cuff, a large cuff, and the appropriate cuff as per arm circumference measurements. "Using a cuff one size smaller than appropriate resulted in...[an overestimation of prevalence of hypertension of] approximately 36%." The important point of this study is that even among borderline arm sizes, appropriate cuff size was important and affected the diagnosis of hypertension.
Wittenberg, C et al. Which Cuff Size is Preferable for Blood Pressure Monitoring in Most Hypertensive Patients? J Hum Hypertens. November 1994. 8(11):819-22.
"These findings suggest that in overweight hypertensives, the use of the standard cuff results in overestimation of BP and that large cuffs should be used exclusively in this population."
Medical Journal Articles About Blood Pressure Measurement Technique
Kugler, J et al. Rise in Systolic Blood Pressure During Sphygmomanometry Depends On The Maximum Inflation Pressure of the Arm Cuff. J Hypertens. July 1994. 12(7):825-9. [from abstract]
Points out that pumping the cuff pressure up too high can artificially raise blood pressure, which they call "cuff inflation hypertension." They state that the "maximum arm-cuff pressure during sphygomanometry should be not too far above the pressure needed to occlude the brachial artery." In other words, pump the cuff up just a little bit above what's needed to get the top number, but not too high or the results might be inaccurate.
Netea, RT et al. Arm Position is Important for Blood Pressure Measurement. J Hum Hypertens. Feb. 1999. 13(2):105-9.
Compared taking b.p. with arms supported on the arm-rests of the chair, and sitting with the arms supported at the level of the mid-sternum (approximation of the "right atrial level"). Putting the arms on the arm-rest raised b.p. on average by about 10 points. "Placing the patient's arms on the arm-rest of the chair instead of at the reference right atrial level, BP measurement will result in spuriously elevated BP values. This may be of great importance for the diagnosis and the subsequent treatment decisions for patients with hypertension."
Krass, ME et al. Blood Pressure Measurement in Family Physician Offices. Fam Med. Jan-Feb 1988. 20(1):25-7.
Surveyed family doctors across NY state about the range of BP equipment available in their offices, and whether BP devices were regularly calibrated. Noted that a number of respondents "did not carry an adequate range of BP cuff sizes suitable for small or large adult arms. Additionally, the majority of family physicians in the sample did not calibrate their BP cuffs in accordance with manufacturer's recommendations. In general, the evidence accumulated leads to questions about the overall accuracy of BP measurement in family physician offices."
Terent, A and Brieg-Asberg, E. Epidemiological Perspective of Body Position and Arm Level in Blood Pressure Measurement. Blood Press. May 1994. 3(3):156-63.
"According to official recommendations, indirect blood pressure (BP) measurement should be performed in the brachial artery at heart level in the seated position." In this sample of 401 healthy men and women of all ages, BP was higher when the upper arm was parallel to the sternum (by the side of the chest) than when the forearm was properly elevated to heart level. The difference was about 10 points in both systolic and diastolic numbers.
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