Pressure Tactics – managing high blood pressure
Measuring your own blood pressure can help you and your doctor prevent or control hypertension and its many complications.
Editor’s Note: In an interview published in the July/August issue of The Saturday Evening Post, clinician and internationally recognized hypertension researcher Dr. Thomas Pickering points out that blood pressure readings in the doctor’s office may be higher than at other times. He recommends the use of home blood pressure monitors to more accurately measure one’s overall, or average, blood pressure level.
In this concluding segment, Dr. Pickering offers more information on how blood pressure readings taken at home and throughout the day can help patients and their physicians more thoroughly monitor the condition. Dr. Pickering is director of the Integrative and Behavioral Cardiovascular Health Program at the Mount Sinai School of Medicine in New York and author of The Good News About Hypertension.
Measuring Your Own Blood Pressure
Our hearts beat about 100,000 times each day, and each heartbeat produces a slightly different blood pressure. During an office visit, your doctor will rarely take more than two or three readings, so if he or she sees you once every three months, these readings will be used to represent the 9 million individual blood pressures that will occur before your next visit.
While in general this assumption holds surprisingly well, there are a number of factors that could produce a transient increase in your blood pressure at the time your doctor takes it, which could also invalidate this assumption.
Factors That Can Raise The Office Blood Pressure
The White-Coat Effect. The basis of the phenomenon of white-coat hypertension is that there are a lot of people who get nervous when they visit their doctor to have their blood pressure checked, which not surprisingly makes the blood pressure go up. Thus the doctor may record blood pressures that are as much as 20 or 30 mm Hg higher than at other times. To some extent, this wears off as you become more familiar with your doctor and the setting in which he or she works, but I have patients whom I have been following for ten years who still show this phenomenon unabated. Most people who are labeled as being hypertensive on the basis of their clinic or office blood pressure have home blood pressures that are lower than the office pressures.
Food and Drink. Contrary to what you may think, eating a Chinese meal the night before you have your blood pressure checked is unlikely to affect it very much. Even infusing salt solution directly into the veins of hypertensive subjects has a negligible immediate effect on their blood pressure. Several studies have investigated the effects of different types of meals on blood pressure, and most have found there is little change, except in older people, who may experience quite a large fall in pressure about 40 minutes after eating. Drinking coffee, on the other hand, can raise pressure.
Smoking. If you smoke just before your blood pressure is measured, it may be 5 mm Hg higher than it would have been otherwise. And the combination of drinking a cup of coffee and smoking a cigarette can produce an even bigger increase that lasts for two hours or more.
Your Mood. If you’ve had a bad day at work, you couldn’t find a parking spot for your car, and then the doctor keeps you waiting, it won’t be surprising if your pressure is found to be high.
Talking. It is not widely appreciated, even by many doctors, that talking can produce a substantial increase of blood pressure. This phenomenon has been described by Dr. James Lynch, who put an automatic monitor on a patient, and observed that when the patient was sitting quietly, he had a blood pressure of 148/78, but when he started to talk, it went up to 162/91. So if your doctor is taking a series of blood pressure measurements, don’t ask what the pressure was after each reading.
The Time of Day. Blood pressure tends to be a little higher in the morning than in the afternoon or evening, although this pattern varies from one person to another. There’s not usually a big difference unless you’re taking medications, in which case the length of time since you took your last pill may make a big difference.
The Season of Year. In temperate climates, where there are large temperature differences between summer and winter, blood pressure tends to be about 5 mm Hg higher in the winter than in the summer.
The Advantages Of Self-Monitoring
All except the last of these problems can in principle be avoided by supplementing the readings taken in the doctor’s office by readings taken outside it. This has two advantages: First, it increases the total number of readings available from which to estimate the overall or average level of blood pressure, which is what is thought to be ultimately important in determining its consequences. Everyone gets the occasional high reading, and the significance (or lack of significance) of these can best be appreciated if there are a large number of other readings, so that they can be put into their proper perspective. When patients first start taking their blood pressure, they are frequently astonished at how variable it is, and no less frequently worried about the few readings that seem excessively high.
The second advantage of measuring your own blood pressure is that it avoids the potentially distorting influence of the doctor’s office, or the white-coat effect. This means that in the majority of patients, the pressure recorded at home is substantially lower than that in the doctor’s office. It may still be high, but when it’s definitely normal (for example, below 135/85 mm Hg), it’s highly questionable whether you should start taking medications.
The Disadvantages Of Home Monitoring
Despite the undoubted benefits of home monitoring, it has to be admitted that it’s not for everyone. Most people actually find it reassuring to learn that their blood pressure at home is not as high as in the doctor’s office, but there is a minority who get panicky at the thought of putting a blood pressure cuff on themselves and can even generate their own white-coat syndrome, whereby the anxiety associated with taking blood pressure can make it go up.
How To Measure Your Blood Pressure
Measuring your own pressure is neither expensive nor difficult, but there are some potential pitfalls. First is the question of equipment. We routinely recommend what is, in fact, the simplest and cheapest device, known as an aneroid sphygmomanometer. This consists of a blood pressure cuff that goes around your arm, connected by a rubber tube to a dial that registers pressure. You also need a stethoscope. The whole thing costs about $30, which may be less than the cost of a doctor’s visit.
The cuff is put on your nondominant arm–that is, your left arm if you’re right-handed. The ones that are easiest to use have a metal buckle or D-ring, around which you can loop the loose end of the cuff, to pull it tight on the Velcro fastener. Before you pump up the cuff, it should be just tight enough to fit snugly around your arm, without actually squeezing it. It’s important to position the cuff correctly, which is on your upper arm, just above the elbow joint. The rubber bag inside the cuff does not occupy its entire length, and should be located with the middle of the bag over the artery, which it will occlude when inflated. With most cuffs, this means positioning the cuff so that the tubes are located toward the inner side of your arm.
The cuff is inflated by screwing tight the knob by the bulb, and then pumping up the bulb to a pressure of about 200 mm Hg, or to well above your systolic pressure. You then unscrew the knob a little, to let air gradually out of the cuff. The ideal rate of deflation is about 2 or 3 mm Hg per second (or about 2 or 3 mm Hg per thud, when you start hearing the sounds).
The stethoscope is placed just below the edge of the cuff over the artery. To find the right position, you should be able to feel the pulsations of the artery by pressing two fingers lightly over the front of your elbow crease, at the bottom of your biceps muscle.
If you’ve pumped the cuff high enough, you should hear nothing at first, but as you deflate it, you’ll start to hear the Korotkoff sounds, which are dull thuds in time with your heartbeats. They are caused by the artery opening and shutting and by blood spurting through the narrowed portion. The first sound that you hear gives you the systolic pressure. As you deflate the cuff further, the sound gets louder, then more muffled, and then starts to fade out. The last sound you hear (technically known as phase 5 of the Korotkoff sounds) gives you the diastolic pressure. Some people advocate taking the muffling (or phase 4) of the sounds just before they disappear, but this is much less reliable, and I do not recommend it.
How Often Should Readings Be Taken?
When you’ve taken the trouble to get out your blood pressure monitor and set it up, it makes sense to take more than one reading. A lot of people find that, even when taking their own blood pressure, the first reading is higher than subsequent ones (the same as happens when a doctor is taking your pressure), so I usually recommend taking a series of two or three readings on each occasion. It’s also a good idea to take readings at different times of day (particularly if you’re taking medications), in case there’s a difference between morning and evening values.
How many days a week you take your pressure depends to a large extent on where you are in your treatment program. If you’re in the early stages, when it’s still not clear whether you need to start taking medication, it’s helpful to take readings relatively frequently (for example, three or four times a week for at least two weeks). When you’re just starting on medication, or when the dose has been changed, frequent readings are again advisable. But if you are on a stable dose and your pressure is controlled, once or twice a month may be all that is needed.
Take Home Messages
In summary, measuring your own blood pressure has a lot of advantages: it enables you to get a series of readings taken over several days or weeks and to establish a baseline level free from the anxiety-provoking influence of the doctor’s office. It’s also a very good way to monitor your response to treatment.
Devices for measuring your pressure are cheap and easy to use; you can either get an aneroid device or an approved electric one, but in either case you should have your doctor check the device and your technique. And, finally, discuss with your doctor how often you should be taking readings, and then keep a written record of the numbers. (Excerpts from Good News About Hypertension.)
RELATED: Buying a Home Blood Pressure Monitor
Many blood pressure monitors are currently on the market for home use and are available in drug, grocery and retail stores, as well as online. Monitor options include manual and automatic wrist and arm cuffs with digital displays and audio readouts. Some models print blood pressure measurement results with time and date, while others are capable of transmitting data over the telephone or Internet.
Blood pressure monitors from the following manufacturers are approved by the U.S. Food and Drug Administration:
* LIFESOURCE a division of A&D Medical www.lifesourceonline.com 1-888-726-9966 (toll-free)
* OMRON www.omronhealthcare.com 1-877-216-1333 (toll-free)
* FORECARE, INC. www.forecare.com 1-877-924-2273 (toll-free)
–Wendy Braun, R.N.
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