What's your blood pressure?

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If you think you know, think again

Here's the folklore of blood-pressure readings: Your doctor unwraps the blood-pressure cuff from your arm and speaketh the words that henceforth shall be known as "Your Blood-Pressure Numbers." These Numbers he will engrave upon a chart, for they are the Truth. And thou must go forth and receive all manner of care and medications because of these Numbers.

But the folklore is all wrong. Fact is, there's a good chance that any single blood-pressure reading you get from your physician is way off the mark. It's likely, our experts say, that a whole lot of people are walking around thinking (wrongly) that they have high blood pressure --and are taking medication to treat a nonexistent condition! And there are probably many people who really do have high blood pressure but believe that their BP is even higher than it really is. You can safely be wrong about many things in life, but blood pressure (BP) is not one of them. Hypertension is definitely not in the same league as hives and hiccups; it puts you at higher risk for heart attack, stroke, kidney damage and other woes, including a shorter life.

Fortunately, good medical detective work has revealed what causes so many blood-pressure readings to lie. Better still, there are ways to counteract the problem and to get BP measurements you can trust. Here's how:

PINPOINT THE CULPRITS
The problem with any single blood-pressure reading is that it's supposed to represent how high your BP is generally -- but in fact it is only a snapshot of your BP at a fleeting moment. Blood pressure naturally fluctuates throughout the day. Plus, it can temporarily spike into the hypertension range for a bunch of reasons. (BPs higher than 140/90 are considered to be in the hypertension range. See "Blood-Pressure Basics" on page 89.) So a single measurement is not going to give you a reliable picture. That single reading taken in a physician's office may or may not reflect the real you at all.

Part of the answer is to take multiple readings, which we'll discuss in a moment. But you have to deal with the causes of those spikes, too. And they're sneaky. Your blood pressure can temporarily jump up -- and show a spike on the pressure gauge -- because you had a cup of coffee less than a half hour before the test. (It's the caffeine that's the culprit, so watch out for other sources, too.) You can also get an unusually high reading if, during a measurement, you talk or have a full bladder. Some over-the-counter medications, especially those with warnings for people with hypertension, may raise your BP, so be sure to tell your doctor if you're taking any.

Probably the biggest source of false high readings lurks just inside the examining room. It's your doctor. "We're notorious for making people's blood pressures go up," says Norman Kaplan, M.D., chief of the hypertension division at the University of Texas Southwestern Medical Center, Dallas. Anxiety is common around physicians (authority figures, you know), and this edginess often results in the psychological phenomenon called white-coat hypertension. One way around this problem is to ask the doctor's nurse or technician to do the blood-pressure reading.

Another source of spikes is cuff size. Regardless of who takes your blood pressure, the wrong cuff size on the measuring device -- often one too small -- can throw your readings off. Say you have large, muscular arms. If you're measured with a "regular" adult cuff when you need a "large," your readings may be falsely high.

And misfits do happen. "What you really want is to have your arm fitted with the proper-sized cuff by your physician," says Donald J. DiPette, M.D., director of the division of general internal medicine, which includes the hypertension section, at the University of Texas Medical Branch at Galveston. A simple way to do this is to have your doctor measure the distance around the middle of your upper arm and select the size cuff that's right for you. If your doctor notes your arm measurement in your chart, there's no need to remeasure at every visit, unless your weight or the size of your muscles has changed significantly.

Don't be shy. You may have to speak up to get good BP measurements. That may mean reminding your doctor or his assistant to take more than one. If your initial readings are high, get another right before you leave --measurements taken at the end of the visit are often lower. Your doctor has to repeat these multiple readings over several visits and then average your results to better estimate your "true" blood pressure.

An alternative to this multiple-visit approach is 24-hour ambulatory monitoring. This involves wearing a small, comfortable monitor that automatically and consistently reads your pressure night and day, while you sleep and even at work -- where telephones and deadlines can get your blood boiling. "This is actually the fastest way to get an accurate diagnosis," says Sheldon G. Sheps, M.D., chief of the hypertension division at the Mayo Clinic in Rochester, Minnesota. "If expense were not a concern, I'd say everyone should do it," says Clarence Grim, M.D., director of hypertension research at the Medical College of Wisconsin, Milwaukee. "But you can teach a person how to take his own blood pressure for less."

DO IT YOURSELF
That's right. The cheapest reliable way to determine your BP is to take your blood pressure yourself. You take frequent measurements throughout the day -- at home, at work, wherever-for two to four weeks until your next doctor visit. Then you can combine your doctor's office readings with those you take on your own and average the whole works. If you already know that you have hypertension, home monitoring lets you keep tabs on your blood pressure so your doctor can better adjust your medication regimen.

Here's how to get the best home-monitoring results:

Select the right equipment. Be choosy about a home monitor. Impulse purchases are always tempting, but don't decide until you hash over the options with your doctor. He can recommend the type and features you'll want.

Keep a diary. Take as many as 30 readings in the course of a few weeks and record the pressures as carefully as you would entries in your checkbook. Include the dates and times and, while you're at it, pen a few words about the way your body feels at the time. What kind of mood are you in? You could be agitated at the kids, mad at the dog or just frustrated because the washing machine broke down again. All the better, says Dr. Kaplan. "It's when you have a headache, when you don't feel well, that we can find out if you really have hypertension."

Master the technique. "Without hands-on training, measurements are frequently done wrong, which is bad news since decisions about your health are based on that information," says Dr. Grim. Review the proper technique (for the specific monitor you have) with your doctor or nurse. To become an ace at the manual monitors (those using hand pump and stethoscope), work with your doctor to personalize the following general instructions (adapted from American Heart Association procedures for health professionals).

1. Sit in a straight-backed chair, even though you may be tempted to pump up while sprawled on the couch. An unsupported back makes muscles contract, thereby raising your pressure as much as 5 mm Hg. "It may not sound like a lot," says Dr. Grim. "But if everyone in the United States were to add that to their readings, we'd double the number of people with high blood pressure in this country." The sitting approach alone doesn't work for some people over age 65, however. "That's because the blood-pressure-regulating mechanism in some older people doesn't work like it used to," says Thomas G. Pickering M.D., associate director of the hypertension center at New York Hospital -- Cornell Medical Center, New York City. "Their pressure may actually fall when they stand up. It's important to be aware of that drop, because if you treat them and make their blood pressure fall even further, they could get dizzy and fall and break a hip or something." These people should have their blood pressures measured while seated and while standing up.

No matter how old you are, it's best to take the reading in a quiet place and do it after you've given yourself at least five minutes to chill out.

2. Position the cuff on your bare upper arm so that the bottom of the cuff is about 1 inch above the elbow. The inflatable portion of the cuff should be centered over the artery that's located on the inside of your upper arm (the brachial artery). "The cuff should be snug enough that you can slide two fingers under it," says Dr. Grim. "If you can't, it's too tight."
3. Position the stethoscope's earpieces in your ears and plant the stethoscope head on the bend in the elbow below the cuff. The right spot is the one where you hear the pulse is strongest. That might mean moving the head of the stethoscope from the bend in the elbow up toward the cuff.
4. Inflate the cuff 30 mm above the systolic pressure you got at the doctor's office and very slowly deflate. "Most people rush this part, and they get poor readings," says Dr. Grim. His advice: Drop at the correct rate of 2 mm to 3 mm per second.
5. Listen up. After a few moments of silence, you'll begin to hear the blood surge. It might tap or swish; it could be loud or soft. Your doctor can help train your ear. (If you hear these sounds as soon as you begin to deflate the cuff, try inflating again to a pressure that's a little bit higher.) Note the reading on the gauge at which these sounds first appear. This is your systolic pressure. To find your diastolic pressure, continue to deflate and note the reading at which the sounds disappear.
6. Wait 30 seconds, repeat the procedure and average the results. If the two measurements are more than 5 mm apart, take a third and average the last two. And remember: There may be some hidden benefits to monitoring your own blood pressure. "Patients who take their own pressures get more serious about trying to lower it," says Dr. Pickering, author of Good News About High Blood Pressure (Simon and Schuster, January 1996). You just might find it easier to exercise more, drop excess weight, stop smoking and just say no to fats and alcohol.
PHOTO (COLOR): Blood pressure indicator

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By Jeanne Craig with Sharon Stocker

BLOOD-PRESSURE BASICS
Blood pressure is represented by two values: systolic and diastolic pressures, which are measured in millimeters of mercury (or mm Hg). They're written like this: 140/90, with the systolic number on top. When the heart contracts, it forces blood to surge through the arteries. This action results in systolic blood pressure. When the heart relaxes, pressure in the arteries drops like an ebbing tide-and that's your diastolic pressure. High blood pressure occurs when blood can't make a swift passage through arteries that are constricted or that may have become stiff with age or blocked by plaque. Your heart pumps harder to force blood through, hiking pressure up when it should be stable.

Here's what different blood-pressure levels (in adults 18 and older) mean:

CATEGORY SYSTOLIC DIASTOLIC
(mm Hg) (mm Hg)

Normal <130 <85
High Normal 130-139 85-89

Hypertension:

Stage 1 140-159 90-99
(mild)

Stage 2 160-179 100-109
(moderate)

Stage 3 180-209 110-119
(severe)

Stage 4 >/=210 >/=120
(very severe)
NOTE: Most hypertensive people show two high numbers, but the condition is usually present if either one is raised. The above are recommendations from the Fifth Report of the Joint National Committee on the Detection, Evaluation, and Treatment of High Blood Pressure (January 1993).

For more information about high blood pressure, contact the American Heart Association at 1-800-AHA-USA1 (242-8721).

YOUR MONITOR OPTIONS
One of your best defenses against hypertension is an accurate blood-pressure reading, and you need the right machine to get if. Here's a list of the different types commonly available at pharmacies and discount drugstores. Your doctor may also have units to loan out. If you decide to buy one, though, test drive the new machine alongside your doctor's to make sure the two are in sync. (It's also a good idea to recheck your machine with your doctor's at least once a year to make sure it's still accurate.) You don't want a new unit that needs to be recalibrated, so before you plunk down cash, check the refund policy.

MERCURY METER
Commonly used by physicians, it measures pressure with a pool of mercury that rises up a tube as air is pumped into the cuff. Accuracy is exceptional, but because it's a manual machine, you need some coordination to use it-the hand that pumps air in and out of the cuff must also hold the stethoscope. You could also ask a spouse or friend for help. If you're on your own, look for units with convenient features, like a stethoscope sewn into the cuff.

ANEROID UNIT
This, too, is a manual device, but unlike the mercury monitor, it measures pressure with a spring gauge. Used properly, this liquidless device can yield measurements close to those obtained with the mercury machine, only it's less expensive.

ELECTRONIC ARM MODEL
It costs more than the manual type, but it can do everything except wrap the cuff around your arm. It's battery operated and comes in semi- and fully-automatic models. Some have microphones built into the cuff and have pressure numbers displayed as vividly as movie credits on a digital screen. Some even inflate the cuffs automatically.

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