Visit a doctor’s office for almost anything that ails you and the chances are good you will have your blood pressure measured. That’s because it is an essential diagnostic procedure to detect a common condition that puts people at risk of heart and kidney disease.
Considering that millions of people have their blood pressure checked every day, it is surprising that this measurement can be so tricky. Mistakes are common, and the consequences of inaccuracies can be serious.
A false positive, that is, a reading higher than the true blood pressure, could lead to unnecessary medication. Drugs can be expensive and may have unpleasant side effects such as dizziness, fatigue, impotence, cough or swollen feet.
A false negative, a reading lower than the actual blood pressure, could lead to undertreatment. This puts people at risk of heart attacks, strokes or kidney disease.
What causes such errors? According to experts writing in the British Medical Journal (April 14, 2001), one of the most common sources of error in measuring blood pressure is using the wrong size cuff. A cuff that is too small for a large arm can result in a blood pressure reading higher than it should be.
Another potential problem is talking. Not infrequently a nurse or physician taking blood pressure will strike up a conversation, thinking that it may put the patient at ease. On the contrary, talking during blood pressure measurement can raise the reading 10 to 20 points.
Other problems include the wrong arm position or a cold examining room, especially if you are wearing one of those flimsy little paper gowns. Feeling chilly and exposed may increase blood pressure more than 10 points.
And speaking of uneasiness, “white coat hypertension” affects up to one patient in five. These are people whose blood pressure skyrockets when the doctor walks into the room. The experts writing in the British Medical Journal note that some people with normal blood pressure may have office readings as high as 180/110.
Anyone who is susceptible to this phenomenon should be measuring blood pressure at home. There are affordable, easy-to-use digital machines that allow people to keep a diary of their readings over the course of several weeks or months. This permits the physician to get a broader understanding of their blood pressure in a variety of settings. The home machine should always be checked against the equipment in the doctor’s office to make sure it is accurate.
Anyone who would like additional details about proper blood pressure measurement, white coat hypertension and drugs used to treat high blood pressure may find our Guide to Blood Pressure helpful. It has a detailed list of dos and don’ts of measuring and managing blood pressure. Here is a link to all our guides. And should you want to know some secrets about common mistakes in treating hypertension, check out our book, Best Choices From The People’s Pharmacy.
Measuring blood pressure is harder than it looks. Getting it right requires good technique and careful monitoring over time. This facilitates the best possible treatment for those who need it and protects others from unnecessary medication.