What's the best cuff for an accurate blood pressure reading?
DEAR DR. ROACH: You recently had a column about a person who measured his blood pressure several times a day. You also recommend home blood pressure cuffs. I have a question about the accuracy of blood pressure cuffs.
I am a 70-year-old male in good general health. The only medication I take is rosuvastatin 10 mg. Recently my blood pressure was taken at my orthopedic doctor's office, using a wrist cuff. The pressure reading was 154. I told the nurse that my blood pressure has never been that high, but that is what she wrote down. I immediately went to my local pharmacy and used their bicep cuff machine, and it read 130. Before that episode, at another doctor's office my blood pressure was taken with a wrist cuff. The nurse saw the reading of nearly 160, looked at me and said, "That can't be right." She went back to the manual method with a stethoscope, and read 130. For my yearly physical, my doctor used a bicep cuff, and it read 128.
It appears to me that the bicep cuff matches the manual method, but the wrist cuff reads considerably higher. When I related my experience with the wrist cuffs to my doctor, he said wrist cuffs are not accurate, especially for older people. What cuff do you recommend for home use? -- D.S.
ANSWER: Home blood pressure monitoring allows for many more blood pressure readings to be taken, and the average of these readings is a better reflection of a person's true range of blood pressures and thus their risk for developing complications of high blood pressure, such as heart attack and stroke. The very best devices, some of which are very expensive, get readings higher than manual readings. This is typically about 5 points but can be as much as 15 points higher. Large studies looking at risk suggest the automated blood pressures are more likely to represent the true risk. I recommend patients with high blood pressure get a home cuff and measure frequently, and prefer those readings to in-office readings to guide therapy. Of course, the home machine must be accurate to do this. Particularly at home, people must be sure to avoid caffeine and smoking before a blood pressure reading, to have a properly sized and placed device and to keep both feet on the floor.
In general, home devices that measure the blood pressure at the arm are more likely to be accurate than those that measure at the wrist or the finger. This is not necessarily a problem with manufacturing: The blood pressure signal is diminished the further it is from the heart.
When choosing a home monitor, I strongly recommend choosing a device that has been independently validated. Online retailers do note this in their listings. Several consumer organizations rate blood pressure monitors. A sampling of those I looked at showed the top picks all to be validated devices. Hypertension Canada has also rated blood pressure devices on its website, hypertension.ca. Under the Hypertension and You tab, click on "Choosing a Blood Pressure Monitor."