Blood Pressure Tests
Blood pressure is the pressure exerted by blood pumped by the heart against the walls of the arteries. The maximum pressure on the arteries is exerted by the contraction of the heart and is called systolic pressure, denoted as the numerator (top number) in a blood pressure reading. As the heart relaxes between heart beats, the pressure in the arteries drops and this pressure is known as diastolic pressure, representing the denominator (bottom number) of the blood pressure reading. Blood pressure varies throughout the day and depends on the level of your activity.
Blood pressure tests may include:
Sphygmomanometer: Blood pressure is usually measured by a device known as a sphygmomanometer, which includes a manometer for reading measurements, an arm cuff, and a rubber bulb. The cuff is placed around the arm and inflated with the bulb until the pressure is raised and no blood flows through the artery. A stethoscope is placed below the cuff above an artery to check for pulse. Pressure is then gradually released from the cuff and your doctor starts listening for pulsation through the stethoscope (systolic pressure). As the cuff pressure drops, the pulsations gradually fade and are not heard (diastolic pressure).
Digital sphygmomanometer: Blood pressure can also be measured with a digital sphygmomanometer. This method also uses a cuff that is inflated and is followed by gradual release of pressure. A microprocessor then detects minor pressure fluctuations in the compressed arteries and measures the mean arterial pressure from prior established measurements.
Invasive blood pressure recording: An invasive method of recording blood pressure is sometimes used, which involves the insertion of a catheter (thin tube), with a transducer attached to its end, into the artery to measure blood pressure.
Ambulatory blood pressure monitoring: ABPM may sometimes be necessary if there is variation in your blood pressure recordings at home and in the clinic setting. It includes a portable device that automatically records your blood pressure throughout the day at regular intervals.