A home blood pressure test allows you to keep track of your blood pressure at home. Blood pressure is a measure of the force of blood inside an artery. A blood pressure measurement is taken by temporarily stopping the flow of blood in an artery (usually by inflating a cuff around the upper arm) and then listening for the sound of the blood beginning to flow through the artery again as air is released from the cuff.

As blood flows through the artery, it can be heard through a stethoscope placed on the skin over the artery. Blood pressure is recorded as two measurements.

• The reading on the gauge when blood flow is first heard is called the systolic pressure. Systolic pressure represents the peak blood pressure that occurs when the heart contracts.
• The reading on the gauge when blood flow can no longer be heard is the diastolic pressure. Diastolic pressure represents the lowest blood pressure that occurs when the heart relaxes between beats.

These two pressures are expressed in millimeters of mercury (mm Hg) because the original devices that measured blood pressure used a column of mercury. Blood pressure measurements are recorded as systolic/diastolic (say "systolic over diastolic"). For example, if your systolic pressure is 120 mm Hg and your diastolic pressure is 80 mm Hg, your blood pressure is recorded as 120/80 (say "120 over 80").

Types of blood pressure monitors

The two general types of blood pressure monitors commonly available are manual and automatic.

Manual blood pressure monitors

Manual models are similar to those that your doctor might use to take your blood pressure. Called a sphygmomanometer, these devices usually include an arm cuff, a squeeze bulb to inflate the cuff, a stethoscope or microphone, and a gauge to measure the blood pressure.

Blood pressure is displayed on a circular dial with a needle. As the pressure in the cuff rises, the needle moves clockwise on the dial. As the cuff pressure falls, the needle moves counterclockwise.

Automatic (also called electronic or digital) blood pressure monitors

Electronic battery-operated monitors use a microphone to detect blood pulsing in the artery. You do not need to listen with a stethoscope. The cuff, which is attached to your wrist or upper arm, is connected to an electronic monitor that automatically inflates and deflates the cuff when you press the start button.

The type of blood pressure monitor typically found in supermarkets, pharmacies, and shopping malls is an electronic device.

Ambulatory blood pressure monitoring (ABPM)

Ambulatory blood pressure monitoring (ABPM) is another method that may be ordered by your doctor if other methods do not give consistent results. It is often used if there is a big difference between the blood pressure readings you get at home and your readings in your doctor's office. You will wear a cuff on one arm and a monitor around your waist. Your doctor's office will fit you with the device and tell you how to use it.