MODEL RELEASED. Blood pressure gauge. Sphygmomanometer used to measure blood pressure in millimetres of mercury (mmHg). An inflatable cuff (brown, bottom right) is placed around the upper arm and inflated using a pump (bottom right) until blood flow in the arm stops. The cuff is then gradually deflated until pulsing blood flow is heard through a stethoscope. The reading on the blood pressure gauge at this point is the systolic pressure, which occurs during a heartbeat. The diastolic pressure, when the heart is relaxed, is taken by deflating the cuff until blood flows smoothly. Blood pressure is an important measure of health. A doctor is examining a patient in the background.