Are you measuring your blood pressure correctly?

1. Electronic sphygmomanometer or mercury sphygmomanometer?

For home measurement, it is recommended to use an upper-arm electronic blood pressure monitor certified by international standards (ESH, BHS or AAMI). my country recommends the use of the ESH standard.

For those who are abnormally obese and have thick and short upper arms, if the thigh cuff is not suitable, you can consider using a verified wrist sphygmomanometer. Electronic sphygmomanometers should be tested at least once a year. You should try to choose a business that provides calibration services or ask hospital staff to help with accuracy testing. The operation steps are as follows: First measure blood pressure with a mercury column sphygmomanometer. After resting for 3 minutes, measure the second time with the electronic sphygmomanometer. Then rest for another 3 minutes and measure the third time with the mercury column sphygmomanometer. Take the average of the first and third measurements, and the difference compared with the second measurement with the electronic sphygmomanometer should generally be less than 5mmHg.

2. How to choose a cuff?

It is currently believed that the cuff bladder should cover at least 80% of the upper arm circumference. What happens if the cuff size is not appropriate? If the cuff is too small, the blood pressure measurement will be too high, and if the cuff is too large, the blood pressure measurement will be too low.

Recommended cuff size:

Thin adult or teenager - extra small (size 12cm x 18cm)

Upper arm circumference 22cm to 26cm - Adult small size (size 12cm x 22cm)

Upper arm circumference 27cm~34cm——Adult standard size (size 16cm × 30cm)

Upper arm circumference 35cm~44cm——Adult large size (size 16cm×36cm)

Upper arm circumference 45cm to 52cm - Adult oversized or thigh cuff (size 16cm x 42cm)

3. How to measure correctly?

For patients with newly diagnosed hypertension or hypertension with unstable blood pressure, it is recommended to measure blood pressure once in the morning (6:00-9:00) and once in the evening (18:00-21:00) every day, and take the average of 2-3 measurements each time; self-measure for 7 consecutive days, and take the average blood pressure of the last 6 days as a reference for evaluating treatment.

For individual patients who are unable to complete blood pressure measurement for 7 consecutive days, it is recommended to measure blood pressure for at least 3 consecutive days, and the average blood pressure of the next 2 days should be used as a reference value.
If your blood pressure is stable and meets the standard, you can measure your blood pressure 1-2 days a week, once in the morning and once in the evening. It is best to measure your blood pressure in a sitting position at a fixed time in the morning after getting up, before taking antihypertensive drugs, breakfast, and after urinating; in the evening, it is recommended to measure your blood pressure before going to bed after dinner, after bathing, and after taking medicine.

4. Left hand or right hand?

It is generally believed that the right brachial artery of the human body comes from the branch of the brachiocephalic trunk, and the left brachial artery comes from the left subclavian artery. The brachiocephalic trunk and the left subclavian artery both come from the aorta, and the brachiocephalic trunk is a larger branch of the aorta, while the left subclavian artery has a smaller branch. Therefore, the blood pressure of the right arm is usually about 5 to 10 mmHg higher than that of the left hand. Therefore, in general, we mainly use the blood pressure of the right upper arm. Only when we visit the doctor for the first time, we measure the left and right arms at the same time and record them. But at the same time, there are studies showing that the branches of the aortic arch from right to left are the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. The branches of the left subclavian artery include the left axillary artery, and the left brachial artery is a branch of the left axillary artery; the branches of the brachiocephalic trunk include the right subclavian artery, and its branches include the right axillary artery, and the right brachial artery is a branch of the right axillary artery. It can be seen from this that the left brachial artery is closer to the center, so theoretically the left brachial artery pressure should be higher than the right side.

In a comparative study on left and right upper arm blood pressure, more than 200 clinical data were analyzed, and the results also showed that the proportion of left upper arm systolic pressure higher than right upper arm systolic pressure (40.7%) was greater than the proportion of right upper arm systolic pressure higher than left upper arm (38.3%). At this point, we will have a contradictory mentality. Should blood pressure be measured on the left hand or the right hand? Suggestion: When measuring blood pressure for patients, blood pressure should be measured on both sides at the first visit, and the side with higher blood pressure should be measured later; or, after excluding the influence of other factors (such as injury to one side of the patient's arm), for the same individual, the outpatient follow-up should choose to measure one fixed arm to achieve the purpose of comparing the before and after data. It should be noted that when diseases such as aortic arch stenosis are suspected, blood pressure in both arms should be measured. If the difference in blood pressure (systolic pressure) between the two arms is greater than 20 mmHg, it is recommended to measure blood pressure in all four arms.

5. Sitting or lying down?

Both are OK, but you cannot cross your legs. The most commonly used positions for blood pressure measurement are sitting or supine, but it should be noted that there are differences in blood pressure measured in these two positions. It has been reported that the diastolic blood pressure measured in the sitting position is 5mmHg higher than that in the supine position, and the systolic blood pressure is not much different. Crossing the legs can increase the systolic blood pressure by 2 to 8mmHg. Some patients need to measure their blood pressure in the upright position. Generally, the systolic blood pressure in the supine position is 5 to 8mmHg higher than that in the upright position, and the diastolic blood pressure is 4 to 6mmHg higher.

6. Do I need to take off my clothes?

Clothes will affect the results of blood pressure measurement, so the upper arm clothes for blood pressure measurement should be removed as much as possible or the thickness should be less than 0.5cm. Note that it should be removed, not rolled up. When the clothes are too thick, the blood pressure measured through the clothes will be higher than that of the bare upper arm, while the blood pressure measured after rolling up the sleeves will be lower than that of the bare upper arm. At the same time, the lower edge of the cuff should be 2 to 3 cm above the elbow, and the tightness should be moderate so that two fingers can be inserted. If the cuff is tied too tightly, the measured blood pressure value will be low; if it is tied too loosely, the measured blood pressure will be high.

7. Where is the airbag located?

When measuring blood pressure, the upper arm should be at the same height as the right atrium. If the upper arm is below the right atrium, the measured value is too high; conversely, if the upper arm is above the heart level, the measured value is too low. For every 2.5cm above or below the heart level, the blood pressure difference is 2mmHg.

When sitting, the right atrium is located in the middle of the sternum, at the level of the fourth rib; when lying down, a small pillow should be used to support the upper arm so that the upper arm is at the same height as the mid-axillary line.

8. Other Frequently Asked Questions

1) For obese people with overly thick upper arms, if there is no suitable cuff, the cuff can be placed on the upper part of the forearm, and the radial artery pulse can be auscultated to measure the pressure. At this time, special attention should be paid to the position of the forearm at the same height as the heart.

2) If both upper arms are not suitable for blood pressure measurement, consider using the lower limbs. Tie the cuff to the lower end of the calf and monitor the dorsalis pedis artery blood pressure. 95% of patients can measure ankle blood pressure.

3) For patients with severe bradycardia (ventricular rate <40 beats/min), the deflation speed should be slower when measuring blood pressure than when measuring normal heart rate. Normally, the deflation speed should be such that the mercury column does not drop more than 2 mmHg per heart beat.

4) For patients with irregular heart rhythm, especially atrial fibrillation, repeated measurements and averaging are required to reduce errors.

Source: Dingxiangyuan official account