One is that everyone's blood pressure varies greatly within a day. Strictly speaking, people's blood pressure is different at every moment. It changes with the change of people's psychological state, time, season, temperature, and the measured part (arm or wrist), body position (sitting or lying). Therefore, it is normal to measure blood pressure differently each time. For example, due to stress and anxiety, people's systolic blood pressure (ie high pressure) measured in the hospital is generally 25 mmHg to 30 mmHg (.. 4 kPa to 4.0 kPa) higher than at home, and some even differ by 50 mmHg (6.67 kPa). Second, the measurement method is incorrect. The following 3 points should be noted when measuring: First, the height of the cuff should be at the same height as the heart position, and the hose of the cuff should be placed at the pulsating point of the brachial artery, and the bottom of the cuff should be 1-2 cm higher than the elbow; at the same time, the cuff should be tightened to be able to just insert one finger. Secondly, be sure to keep quiet for about 10 minutes before measurement. Finally, the time interval between two measurements should not be less than 3 minutes, and the position and position should be the same. To achieve these 3 points, it should be said that the measured blood pressure is accurate and objective. Alternate method measurement: The first time the doctor measures the blood pressure with a mercury column sphygmomanometer, after resting for 3 minutes, the second time is measured with an electronic sphygmomanometer, and then the rest is 3 minutes, and then the doctor measures the third time with a mercury column sphygmomanometer. Take the average of the first and third times as the doctor's measurement value. Compared with the electronic sphygmomanometer measurement value, the difference should generally be less than 10 mmHg (1.33 kPa). An electronic sphygmomanometer that meets this condition can be used with confidence.