If a patient has a systolic blood pressure of 120 millimeters of mercury what is the complete unit of this measurement?

The complete unit of measurement for blood pressure, including a systolic reading of 120 millimeters of Mercury, is expressed as mmHg. This unit indicates the pressure exerted by the blood against the walls of the arteries, with "mm" representing millimeters and "Hg" standing for mercury, which is the substance historically used in barometers and sphygmomanometers.