January 31, 2013

Tips on Blood Pressure Monitoring

I used to visit my internist for my annual physical, roll up my sleeve, have him take a blood pressure reading (or two), and listen for the numbers. That was my blood pressure.

Recent research suggests that BP readings aren't as accurate as they should be. As a result, many people are easily misdiagnosed. Usually mistakes skew to the high side, so people are sometimes put on medication unnecessarily, or given doses that are too high.

Our BP fluctuates throughout the day. Evaluating it is like shooting at a moving target. All sorts of things can cause BP to rise or dip. Did you know, for example, that you shouldn't smoke, exercise, or drink caffeine for the 30 minutes before being tested?

The possible variations don't matter too much if you're clearly hypertensive, or clearly normal. But most of us are in the middle "gray area."

Recommended Guidelines
A standard way to measure BP has been recommended by the American Heart Association. Here's a summary:

The Setting: Ideally, you should wait five minutes in a quiet room before being tested. Neither you nor your doctor should talk during the test. You should sit on a chair (not the examination table) with your back supported, feet flat on the floor, sleeve rolled up, and forearm supported by the practitioner at heart level. Using a cuff that's too small for a large upper arm will give an erroneously high reading.
Multiple tests: Two measurements should be done, at least a minute apart, and the results averaged. Even if the numbers suggest your BP is elevated, it isn't sufficient to diagnose hypertension unless those numbers are quite high. In most cases, your doctor should check it again in subsequent visits. You should check it at home, too, before making any decision about treatment.
Two arms: At least at the initial visit, BP should be measured in both arms, with the second arm tested at least five minutes after the first. Most practitioners don't follow this recommendation. In many people, the readings will differ significantly, in which cases the numbers should be averaged. If the difference is big, the arm with the higher pressure should always be used.

The Gold Standard
If after all this your doctor says you have mild or borderline hypertension, you still might want to ask her about the possibility of a 24-hour "ambulatory" BP testing, before going on medication. You wear a device that automatically measures BP every half hour or so and stores the results.

About one fourth of the people with a high reading in a clinic will not have a high ambulatory result.

If you're already on medication for mild hypertension, you might want to ask your doctor if it would be a good idea to do a 24-hour test while you're off the medication.

Check Your Own Blood Pressure
I visit doctors and clinics often these days and get my BP checked frequently. No practitioner comes close to meeting the AHA guidelines on monitoring blood pressure.

I wonder if you've come across a doctor who follows these guidelines. I doubt it.

It's particularly troubling when doctors end up prescribing hypertension medication based on questionable readings. The prescribing doctor usually assumes the patient will be on a BP medication for life.

Researchers consistently find that readings taken in a doctor's office or clinic are too high more than one fourth of the time -- the so-called "white-coat hypertension." A 2008 statement issued jointly by the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nurses Association recommends that if you have been diagnosed as having hypertension or borderline hypertension, you should be checking your BP at home on a regular basis.

The statement says:
There is rapidly growing literature showing that measurements taken by the patients at home are often lower than readings taken in the office and closer to the average blood pressure recorded by 24-hour ambulatory monitors, which is the blood pressure than best predicts cardiovascular risk. 
The older you are the more important self-monitoring is. Older people have more fluctuations in blood pressure than younger people. And older people are often taking other prescription or over-the-counter medications that can raise blood pressure or interact with blood pressure meds.
My Experience
I bought a home BP monitor over a year ago. (Consumer Reports rates them.) I wanted one because the OTC serotonin-booster, 5-HTP -- one of the three supplements I still take -- can cause pressure spikes.

Since I've been monitoring my pressure, I decided to see if I could cut my blood pressure pill in half and still keep the readings in the acceptable range. I could.

Recently, I've seen reports indicating that higher BP may actually be desirable for people in my 80-and-older club. I reported on this yesterday. Now I'm experimenting with taking half a pill every other day and continuing to monitor my pressure. So far, the readings are in the acceptable range under the new guidelines.

I take a BP reading every morning and evening and record the numbers.

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