Which unit is standard for measuring blood pressure?

Which unit is standard for measuring blood pressure?

• A. mmHg
• B. cmH2O
• C. inches of water
• D. feet of water

Answer: (A)

Blood pressure is measured in millimeters of mercury because the reading comes from balancing the arterial pressure with a column of mercury. The height of that mercury column, measured in millimeters, directly reflects the pressure inside the arteries, so values are given as mmHg (for example, 120/80 mmHg). This unit is standard in clinical practice and is what most devices are calibrated to display. Other units like centimeters or inches of water measure much smaller pressures and are used in different fields (such as respiratory therapy or fluid systems). They wouldn’t conveniently express the typical arterial pressures we see in humans, which are on the order of hundreds of millimeters of mercury, so they aren’t standard for blood pressure readings.

Blood pressure is measured in millimeters of mercury because the reading comes from balancing the arterial pressure with a column of mercury. The height of that mercury column, measured in millimeters, directly reflects the pressure inside the arteries, so values are given as mmHg (for example, 120/80 mmHg). This unit is standard in clinical practice and is what most devices are calibrated to display.

Other units like centimeters or inches of water measure much smaller pressures and are used in different fields (such as respiratory therapy or fluid systems). They wouldn’t conveniently express the typical arterial pressures we see in humans, which are on the order of hundreds of millimeters of mercury, so they aren’t standard for blood pressure readings.