company news about Influence of Compression Cuff on Blood Pressure Measurement

Influence of Compression Cuff on Blood Pressure Measurement

When taking blood pressure measurements, we often emphasize what the patient must do to get an accurate reading. And little is said about the effect of the size of the blood pressure cuff itself on blood pressure readings. In fact, if we choose the wrong cuff size, it will result in the wrong blood pressure level measurement.

Types of blood pressure cuffs

According to the cuff structure, we can divide cuffs into non-airbag cuffs (or integrated cuffs) and airbag cuffs (also known as cuffs with inflatable bags). The non-airbag cuff combines the airbag and the cuff into one, and the design is more compact and easy to carry, while the airbag cuff is divided into two parts: nylon cuff and PVC airbag. The airbag can be replaced when it is damaged.

Depending on the number of patients used, there are reusable blood pressure cuffs and single-patient use of disposable cuffs. Reusable cuffs are available for different patients. Therefore, we must sterilize after use to prevent cross infection. Disposable cuffs are intended for use by only one patient in the hospital. So we don't have to worry about cross infection. Disposable cuffs are usually used for patients in departments with poor immunity or susceptible to infection, such as ICU, NICU, emergency room, etc. Even though we have different types of cuffs, they just help the medical staff choose the right cuff for the patient. They have no effect on the measurement results.

How to get an accurate blood pressure reading?

Hand and upper arm measurements give us the most accurate blood pressure readings. To get accurate measurements, we must choose the right size blood pressure cuff and place it in the right position.

How to choose the size of non-invasive blood pressure cuff?

Before choosing a blood pressure cuff size, we need to know our upper arm circumference. The size of the cuff is determined by the upper arm circumference, and the wrong size can result in a wrong measurement. To avoid incorrectly sized blood pressure readings that are too high or too low, the length of the cuff balloon should not be less than 80% of the circumference of the upper arm and the width should not be less than 40% of the circumference of the upper arm.

If the cuff balloon is less than 80% of the circumference of the upper arm, it may cause the balloon to fail to cover the artery and require more air pressure, resulting in a high reading. A cuff that is too large on the arm can cause the balloons to overlap, in which case we need less air than we actually need to compress the artery and result in a lower than normal blood pressure reading. That is to say. With the same size blood pressure cuff, for thinner arms, less air in the cuff can block arterial blood flow, resulting in lower blood pressure. And with fatter arms, we need more air, which increases blood pressure.

Since there is no industry standard for blood pressure measurement in China, under normal circumstances, we will learn from European and American standards. The blood pressure measurement cuff size recommended by the American AHA Association,

Patient-recommended cuff size

Adult (by arm circumference)

22 to 26 cm 12 × 22 cm (small adult)

27 to 34 cm 16 × 30 cm (adult)

35 to 44 cm 16 × 36 cm (large adult)

45 to 52 cm 16 × 42 cm (adult thigh)

Children (by age)*

Neonatal and premature infants 4 × 8 cm

Baby 6 x 12 cm

Older child 9 x 18 cm

Cuff tightness and position in blood pressure measurement

Correct cuff size is a prerequisite for obtaining accurate blood pressure measurements. If we want accurate blood pressure readings, we also need to consider the tightness and position of the cuff. When measuring blood pressure, the tightness of the cuff should be appropriate. It is best to leave room for one finger to be inserted, and the cuff should be positioned 2-3 cm from the elbow.

If the cuff is too tight, the measured blood pressure is lower than the actual blood pressure; if the cuff is too loose, the blood pressure measurement will be higher. The idea is that when the balloon is too tight, less inflation (pressure inside the cuff) blocks arterial blood flow, so the measured blood pressure is low. Conversely, when the balloon is too loose, it will inflate more than it normally needs, resulting in a higher blood pressure reading than the actual blood pressure.

If the cuff is positioned too low to cover the elbow, the measured blood pressure is higher than the actual blood pressure. Because of the low position, when the arm is flexed, the balloon compressing the brachial artery narrows and requires more inflation to block arterial blood flow, resulting in a higher blood pressure measured than the actual blood pressure.

Therefore, in order to obtain accurate blood pressure readings, it is necessary to select the appropriate size cuff and place it in the correct position. Only in this way can the patient obtain accurate blood pressure in the correct blood pressure measurement posture.