If the cuff of the sphygmomanometer is tied too loosely or too tightly when measuring blood pressure, it will have an effect on the blood pressure measurement. If the cuff of the sphygmomanometer is tied too tightly, the measured value will be higher than the patient’s true blood pressure. Conversely, if the cuff of the sphygmomanometer is tied too loosely, the measured value will be lower than the patient’s true blood pressure. In addition, there are other precautions to take when measuring blood pressure, such as no smoking, no coffee, and emptying the bladder for half an hour before the blood pressure measurement. In a quiet environment, sit on a chair with a backrest and rest quietly for about 5 minutes, and measure with the upper limbs bare.