Author: Zhang Yuqing (Fuwai Hospital, Chinese Academy of Medical Sciences)
For many people with risk factors for high blood pressure, or who have been diagnosed with high blood pressure, doctors recommend monitoring blood pressure frequently, even several times a day at different times.
Many people think that measuring blood pressure is easy, but in fact, it is not easy to measure accurately, and many aspects need to be paid attention to.
The inaccurate blood pressure measurement is one of the important factors affecting the doctor’s judgment. Let’s talk about the knowledge of this “not difficult” blood pressure measurement.
First, first, make preparations for measurement
1. Blood pressure monitor
Currently commonly used sphygmomanometers mainly fall into two categories: mercury column sphygmomanometers that meet measurement standards, or upper arm electronic sphygmomanometers certified by international professional organizations.
Mercury sphygmomanometers and electronic sphygmomanometers need to be calibrated by professional institutions once a year. Only after calibration can the measurement be accurate.
Among them, mercury sphygmomanometer measurement requires professional auscultation skills and methods, and cannot measure self-measurement. Therefore, self-measurement of blood pressure at home is generally recommended to use an upper arm electronic sphygmomanometer.
Image source: Zhanku Hailuo
2. Cuff
The air bag of the cuff should cover at least 80% of the upper arm, and the air bag width should be approximately 40% of the circumference of the upper arm.
The arm circumference of most adults is about 25~35 cm, and a standard cuff can be used (currently commercialized mercury sphygmomanometers in China, the air bag size is 22~26 cm long , width 12 cm); people who are obese or have a larger arm circumference should use a large-sized airbag cuff; children in the growth and development stage need to choose the appropriate size of the airbag cuff according to the upper arm circumference, otherwise it will affect the measurement results. accuracy.
3. Environment
The surrounding environment is quiet, the measurement space is sufficient, and the room temperature is 20°C~24°C; when measuring in a sitting position, you need to prepare a table with a suitable height and a chair with a backrest.
4. Subjects
Within 30 minutes before the blood pressure measurement, do not smoke, drink, coffee, tea and other beverages that affect blood pressure, do not do strenuous exercise, empty urine, and sit and rest for 5-10 minutes.
Usually in a sitting position, the subject’s back is naturally straight on the back of the chair, and the upper arms are fully exposed (many people will roll up too many or too thick sleeves, and the backlog Above the cuff, which is not right), place your forearms on the table with your upper arms at the same level as your heart; feet flat on the floor, knees not crossed.
If the subject cannot maintain a sitting position, the measurement can be taken in a supine position, keeping the brachial artery at the same level as the heart.
Image source: Zhanku Hailuo
Secondly, pay attention to the following matters during the measurement process
1. Mercury sphygmomanometer
Tie the cuff tightly to the upper arm of the subject and fix it well. It is better for the cuff to touch the skin so that it is comfortable and natural. A forefinger can just be placed between the cuff and the arm. The lower edge of the strap should be about 2-3 cm above the bend of the elbow.
Place the stethoscope tip on the brachial pulse, inflate rapidly so that the pressure in the balloon reaches the point where the radial pulse disappears, then increase by 30 mmHg, and then decrease at a constant rate (decrease per second) 2~6 mmHg) slowly deflate, and hear the first sound (scientific name of Korotkoff sound phase I: first sound) and the last sound (scientific name of Korotkoff sound phase V: disappearance sound) from the stethoscope ), the measurer observes the vertical height of the convex surface of the mercury column, and the corresponding readings are systolic and diastolic blood pressure.
After the blood pressure measurement, record the heart rate, and record whether you took medicine on the day of the measurement.
As mentioned above, the mercury column sphygmomanometer needs to be used by professionals, and is rarely used for home blood pressure self-testing.
Image source: Zhanku Hailuo
2. Electronic sphygmomanometer
Imitate the binding method of the mercury column sphygmomanometer, install the cuff correctly, place the brachial artery marker on the cuff on the brachial artery, turn on the power switch, press the measurement button, and wait for the blood pressure The meter automatically pressurizes, deflates, and displays diastolic, systolic, and heart rate.
3. Number of measurements
In order to ensure the accuracy of blood pressure measurement, it is necessary to measure the second time at 1~2 minutes interval, and take the average value. If the difference between two consecutive measurements exceeds 5 mmHg, the measurement should be repeated.
For the first measurement, it is necessary to measure the blood pressure of both upper extremities, select the side with higher blood pressure, and use this side for measurement in the future. Hypertension patients diagnosed for the first time can be measured continuously for 5 to 7 days, and at two fixed time points in the morning and evening. But it is not recommended to measure too much or too frequently.
*The content of this article is for the popularization of health knowledge. It cannot be used as a specific diagnosis and treatment recommendation, nor can it replace the face-to-face consultation of a licensed physician. It is for reference only.
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