A person is seated with his or her bare arm resting on a table. The arm is bent at the elbow so that it sits at the same level as the heart. A blood pressure cuff is placed on the upper arm and inflated. A technician wearing a stethoscope listens carefully as air is slowly let out of the cuff. He or she notes the systolic and diastolic pressures.
Systolic pressure is the blood pressure at the time the heart is contracted.
Diastolic pressure is the blood pressure at the time the heart is relaxed. No preparation is needed for a blood pressure reading. High blood pressure is defined as a systolic blood pressure reading greater than 140 mm Hg or a diastolic blood pressure reading greater than 90 mm Hg. The National Institutes of Health has further defined high blood pressure. These categories are for people 18 years and over, who are not taking medication for high blood pressure and who do not have a short-term serious illness.