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Figuring out What size cuff you need
DateTime:2008-8-17 9:40:47  

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.

Step One - Know Your Arm Size
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:
1.Adult 'Standard' or 'Regular' Cuff - fits most average-sized people
2.Large Adult Cuff - fits most plus-sized people
3.Adult 'Thigh' Cuff - fits most supersized people or mid-sized people with heavy arms

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:
ˇ¤Providers using a 'regular' cuff when a 'large' cuff is needed. This error is extremely common.
ˇ¤Providers using a 'large' cuff for all obese people, even when a 'thigh' cuff is really needed. This is also common, but unfortunately it is rarely recognized as a problem.
ˇ¤Using a 'thigh' cuff for super-obese people, even when the upper limits of the thigh cuff are surpassed

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


*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 is adapted from http://www.americanheart.org/presenter.jhtml?identifier=3000861.)

**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.


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