Posted on: Saturday, August 21, 2004

PRESCRIPTIONS
Blood pressure can be measured wrong

By Landis Lum

Q. At the doctor's, the blood-pressure monitor is at the level of my head, and my pressure is higher than normal. Shouldn't the monitor be at heart level?

A. Actually, it's the arm cuff that should be at heart level. If the cuff is above the level of the heart, then readings will be falsely low; if below heart level, they'll be too high. And avoid wrist cuffs — I found one study showing they're inaccurate for systolic (the upper number) pressures, and another finding they're bad for diastolics (lower number).

The alarming thing about high blood pressure is that it is silent — you feel normal. No headaches, tiredness, dizziness. And then you may wake up one morning permanently paralyzed and unable to speak — victim of a stroke.

Or you get shortness of breath from heart failure. These complications start occurring above a blood pressure of only 115 over 75, and will double if the top number gets to 135, or the bottom number gets to 85, with even further increases in complications with higher numbers.

Above age 50, the top number is a more important predictor of risk than the lower number. And just because you're older than 50 and your blood pressure has been, say, 160 all your life doesn't mean it's safe — anything over 140/90 (or 130/80 if you have diabetes or kidney disease) should be lowered at any age!

Coffee or smoking may raise pressure, while vigorous exercise may reduce it for several hours. Avoid caffeine, exercise, and smoking at least 30 minutes before readings. You should ideally sit quietly for at least five minutes in a chair with feet on the floor and arm supported at heart level.

The cuff bladder should encircle at least 80 percent of the arm. Inflate cuff 20 to 30 points higher than where you feel (by touch) the pulse in your wrist or arm disappear, then deflate it 2 to 3 points a second. If one arm always has higher pressures, the arm with the higher pressure reflects the true blood pressure.

See an article from July 19, 2003 to learn more about dealing with high blood pressure.

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the John A. Burns School of Medicine, University of Hawai'i. Send your questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; or write islandlife@honoluluadvertiser.com. This column is not intended to provide medical advice.