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Monitoring Blood Pressure at Home

If you have been diagnosed with high blood pressure, known medically as hypertension, your doctor may recommend that you use a home monitor to check your blood pressure between visits.

WebMD Feature

Reviewed By Michael Smith

High blood pressure has been called the "silent killer." The name may seem grandiose, but it's unfortunately accurate: High blood pressure has no symptoms and it can lead to life-threatening illnesses, strokes, and heart attacks. While 50 million people in the U.S. are estimated to have high blood pressure, as many as a third of them may not know it.

If you have been diagnosed with high blood pressure, known medically as hypertension, your doctor may recommend that you use a home monitor to check your blood pressure between visits. Despite what you might think, devices that you can buy in the drugstore or at the mall can be reliable, accurate, and affordable. But there are a lot of monitors out there, and it's crucial to get a good one.

What Kind Should I Use?

Of the different types available, Sheldon Sheps, MD, emeritus professor at the Mayo Clinic in Minnesota, says that you should get only an electronic one with a digital display. The other kinds -- such as aneroid or mercury devices -- require training with a stethoscope to get accurate readings.

"The automated electronic equipment is very simple to use and very reliable," says Michael Weber, MD, Professor of Medicine at the SUNY Health Science Center in Brooklyn. "They're so accurate that many clinical trials are now actually using the same blood pressure machines that you can buy from the drugstore."

However, of these electronic devices, Weber and Sheps urge you to get a device that measures your blood pressure with a cuff around the arm. Don't buy one that works on the wrist, and definitely avoid finger blood pressure monitors, since they are especially unreliable.

A good device costs between $40-$60, although models with additional features are pricier. Some offer a self-inflated cuff, which saves you the trouble of pumping it up yourself. Other devices have a memory of previous readings, and some even print a record each time you use it. Sheps observes that a company's line of devices will often all use the same microchip, so a no-frills model is often as accurate as a more expensive one made by the same company.

Of the extra features, Weber and Sheps suggest getting the self-inflating cuff. For one, pumping it up may be difficult for people with arthritis. "And pumping is a muscular activity," says Sheps, "so it can actually affect your blood pressure reading."

One of the most important things to consider when buying a device is to make sure that the cuff fits your arm. If it's too small or too big, you won't get correct readings. As a rule of thumb, make sure that the cuff fits easily around your arm with fabric to spare. If the cuff that comes with your monitor doesn't fit, you may be able to get a larger one from a drugstore or directly from the manufacturer.

And don't forget to shop around. "The same device may cost twice as much at a medical supply store as it does at a chain store," says Sheps.

Stay Away From In-Store Machines

What about those freestanding blood pressure machines that supermarkets and pharmacies have set up in lobbies and waiting areas? Both Weber and Sheps say you can't rely on them.

"I am not enraptured with those machines," says Weber. "They get a lot of abuse, and it's hard to tell if they're being maintained and calibrated."

In addition, the cuff size may not fit correctly or it may be uncomfortable, and people with arthritis may have difficulty getting their arm into the machine.

Going to the Doctor

One benefit to self-monitoring is that it allows you to see if your high blood pressure is really just "white-coat hypertension." For many people, just the sight of a stethoscope or the smell of a doctor's office waiting room can send the blood pressure skyrocketing, even if it's normal most of the time. Unless you take readings outside of a medical setting, there's no way to tell if you really do have high blood pressure or not.

Sheps observes that self-monitoring can also help with the reverse: People who have normal blood pressure in the doctor's office but high blood pressure elsewhere, such as on the job.

As useful as they are, your own readings from a blood pressure monitor are no substitute for regular visits to the doctor. Instead, they are just a supplement.

It's important that you periodically check your device against the readings your doctor gets when he or she takes your blood pressure. In fact, Sheps and Weber recommend that you bring your monitor to your doctor after you buy it to make sure that it's accurate, that you have the right cuff size, and that you are using it correctly.

Also, some people may not be able to get accurate blood pressure readings because of certain illnesses or birth defects.

In certain cases, your doctor may recommend something called ambulatory blood pressure readings. A series of blood pressure readings are done outside the doctor's office with a device that automatically checks your pressure a number of times over several hours or days. Typically, you would wear the device for a day or longer and return it to the doctor's office, where he or she could check the readings.

Taking Charge

One of the greatest benefits of monitoring your blood pressure yourself is that you will have a much better understanding of your condition. By taking your blood pressure regularly, you can easily tell if your medications are working. You might be inspired to exercise more if you can see the concrete effect it has on lowering your blood pressure.

"We highly recommend self-monitoring of blood pressure," says Sheps. "It helps to have the patient partner with the physician."

Weber agrees. "People who check their own blood pressure tend to be more conscious of the importance of taking their medication on a regular basis," says Weber, "and they tend to be the sort of people who notice the foods or behaviors that raise their blood pressure" and adjust their lifestyle to avoid them.

"It's my belief that patients who get involved in managing their own high blood pressure have much better results and much better outcomes," says Weber.