From the Guidelines
Using a blood pressure cuff that is too small for a person's arm will result in falsely elevated blood pressure readings. When taking blood pressure measurements, always use an appropriately sized cuff that covers at least 40% of the arm circumference in width, with the ideal being a cuff width of 46% of the arm circumference, as shown in a study by 1. A cuff that is too small creates excessive pressure on the artery, requiring more force to allow blood flow, which artificially increases the reading. This error can be significant, potentially leading to misdiagnosis of hypertension or unnecessary medication adjustments.
Key Points to Consider
- The American Heart Association recommends specific cuff sizes based on arm circumference:
- For arm circumference of 22 to 26 cm, the cuff should be “small adult” size: 12 x 22 cm
- For arm circumference of 27 to 34 cm, the cuff should be “adult” size: 16 x 30 cm
- For arm circumference of 35 to 44 cm, the cuff should be “large adult” size: 16 x 36 cm
- For arm circumference of 45 to 52 cm, the cuff should be “adult thigh” size: 16 x 42 cm, as stated in 1.
- For accurate readings, measure the patient's mid-upper arm circumference and select the proper cuff size.
- The bladder of the cuff should encircle at least 80% of the arm without overlapping, as recommended by 1.
- In patients with morbid obesity, alternative methods such as measuring blood pressure from a cuff placed on the forearm or using a validated wrist blood pressure monitor may be necessary, as noted in 1.
From the Research
Effect of Small Blood Pressure Cuff on Readings
- A small blood pressure cuff can lead to overestimation of blood pressure readings 2, 3.
- Studies have shown that using a cuff that is too small can result in falsely high blood pressure values 3.
- Systolic and diastolic blood pressure were overestimated by 2-6 mm Hg in men and 3-4 mm Hg in women when the cuff was one size smaller than appropriate 2.
- The use of a single width cuff, regardless of arm circumference, can lead to inaccuracies in blood pressure measurements and may result in misdiagnosis of hypertension 3.
Importance of Proper Cuff Size
- Proper cuff size is crucial for accurate blood pressure measurements 4, 5.
- The American Heart Association recommends that cuff size should be based solely on limb circumference 5.
- Using a cuff that is too small or too large can lead to distorted blood pressure readings, with an average error of 8.5 mm Hg systolic and 4.6 mm Hg diastolic 5.
- A universal cuff may not be suitable for all arm circumferences, and using an appropriately sized cuff can help avoid overestimation of blood pressure readings 6.