Does the size of the cuff affect the accuracy of blood pressure readings?

The answer is yes, a new study has found that the wrong size of a blood pressure cuff may affect the accuracy of blood pressure readings and, in turn, the accuracy of medical diagnoses. Blood pressure cuffs come in different sizes, and health care providers should use the cuff that best fits the patient's arm size. 

In one study, researchers found that when they used routinely smaller sized cuffs on patients with larger arms, they often produced highly inaccurate measurements. In patients with "oversized" arms, blood pressure cuff measurements increased systolic blood pressure by an average of 20 points. In fact, one study found that 39 percent of study participants were misdiagnosed with high blood pressure because the cuff size was too small.

On the other hand, when a loose cuff was used to measure blood pressure in adults with smaller arms, the measurement was 4 percentage points lower than normal. While this wasn't as significant as the effect of the tight cuff, it still made a significant difference: The study found that using a cuff that was too loose led to a misdiagnosis of high blood pressure in 22 percent of study participants. Accurate blood pressure measurement is common, both in health care Settings and at home, and requires the right steps to use, including choosing the right cuff size. 

Cuff size is also important for home blood pressure monitoring. Some home health devices come with cuffs that fit multiple arm sizes. There are also monitors with oversized cuffs -- and of course, they can cost a lot more than other devices. Cuff size isn't the only problem, though. People using home monitors need to pay attention to position (sit up straight, feet on the floor, arms at chest level) and time (measured after using the bathroom, after sitting for five minutes). It is important to keep these steps in mind. If you are using a blood pressure monitor at home, it is recommended to have the device and cuff size calibrated regularly by a professional to ensure accurate readings are obtained.