Blood pressure is commonly measured by a nurse or other health care provider by either an automatic blood pressure cuff or a blood pressure cuff and stethoscope.
Two numbers are recorded when measuring blood pressure:
- The top number, or systolic pressure, refers to the pressure inside the artery when the heart contracts and pumps blood through the body.
- The bottom number, or diastolic pressure, refers to the pressure inside the artery when the heart is at rest and filling with blood.
Both the systolic and diastolic pressures are recorded as "mm Hg" (millimeters of mercury), which represents how high the mercury column in the blood pressure cuff is raised by the pressure of the blood. The following numbers are used to assess normal blood pressure, pre-hypertension and high blood pressure in most adults:
- Normal Less than 120 mm Hg systolic pressure and less than 80 mm Hg diastolic pressure
- Prehypertension 120-139 mm Hg systolic pressure and 80-89 mm Hg diastolic pressure
- High blood pressure Stage 1 - 140-159 mm Hg systolic pressure and 90-99 mm Hg diastolic pressure;Stage 2 - 160 mm Hg or higher systolic pressure and 100 mm Hg or higher diastolic pressure
These numbers should only be considered a guide, as a single elevated blood pressure measurement is not necessarily an indication of a problem. A health care provider will want to see multiple blood pressure measurements over several days or weeks before diagnosing high blood pressure and starting treatment.
Everyone should have his or her blood pressure checked at least once a year. People at risk or who have already been diagnosed with hypertension, however, should check their blood pressure more frequently.
