Accurate blood pressure measurement requires that the sphygmomanometer is in good condition, that there is no interference in the environment, that the person taking the measurement is well prepared, and that the blood pressure cuff is placed in the correct position. The sphygmomanometer is in good condition: If it is a mercury sphygmomanometer, the sphygmomanometer’s mercury should be checked for damage before measuring blood pressure. The environment is free of interference: The environment where the blood pressure is measured should be quiet and well lit to facilitate the reading of blood pressure values. Preparation of the person taking the measurement: The person taking the measurement should ensure that he/she has not had any strenuous exercise or coffee 30 minutes before the measurement; if the person takes the measurement in a sitting position, he/she should put his/her feet flat on the ground and should not cross his/her legs to affect the blood flow back to the patient. Placement of the blood pressure cuff: The lower part of the cuff should be 2.5 centimeters above the bend of the elbow, and the height should be at the same level as the position of the heart.