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QUESTION: I have been receiving treatment for hypertension and wanted to monitor my blood pressure at home. Could you explain how to do this and what type of equipment is best to use. My treatment involves exercise and a change in diet. Thank you.

ANSWER: Actually, measuring blood pressure is quite a simple procedure and you can learn to do it in just a few minutes. However, you may want to have someone else in your household learn to take your blood pressure, because it is difficult to do for yourself.Taking blood pressure requires listening for sounds of blood flowing through the artery of the upper arm while pressure is released from the cuff. To take blood pressure, wrap the blood pressure cuff around the upper arm and pump up the cuff until blood flow is occluded. The amount of pressure needed to occlude the vessel varies with the person's systolic pressure, but usually a pressure of 160 mm Hg. is a good place to begin.

Then, listen with the stethoscope on the soft inner surface of the elbow while you release the pressure slowly from the cuff. When the pressure of the cuff decreases to the pressure exerted by the heart as it contracts (called systolic blood pressure), blood will begin to flow through the artery, and you will hear this flow through the stethoscope. The pressure that corresponds to this sound is recorded as systolic pressure.

As you continue to release the pressure, the sound will begin to muffle and at some point will disappear. The pressure associated with the disappearance of sound is called diastolic pressure and is equal to the pressure in the arteries between heart contractions.

Normal blood pressure readings are about 120/80. This means that the heart applies about 120 mm Hg. pressure on the blood vessels of the arms during contraction and that there is a residual pressure of about 80 mm Hg. between beats. Blood pressure below 140/90 is considered normal, but if the systolic is between 140 and 160 or the diastolic between 90 and 104, it may be considered mild hypertension.

There are several different types of blood pressure devices (called sphygmomanometers). Your physician probably uses one with a mercury column. These are more expensive but also more accurate. If you buy one, you will probably get an aneroid device (with a circular dial). Both of these require a stethoscope. Electronic sphygmomanometers are now available that do the listening for you. You simply pump it up, release the pressure, and the blood pressure is displayed on a digital meter or printed on a tape.

Some helpful guidelines for home blood pressure use were printed in the April 1989 Aerobic News (Cooper's Clinic):

1. Make sure you use the proper sized cuff. If your arm is more than 13 inches around, you need an oversized cuff.

2. Ask your doctor (or his nurse) to check your blood pressure readings and observe your technique.

3. Compare your device with a mercury device every six months and inspect your cuff for leaks from time to time.

4. Rest for about five minutes before taking blood pressure. Don't take it immediately after exercise or the comparison to resting levels will not be accurate.