Dear Dr. Roach: During my annual wellness visits to the doctor, my blood pressure is always taken. But it is done differently depending on the person taking it. How many times should the pump be used, and does it make a difference in the reading?
My readings are coming out hugely different. This last reading was 120/82. Last year it was 160/94, and the previous year 180/110. It was never high until the two high readings.
This year the person taking it only pumped it about four times. In previous readings, the nurse pumped it until I felt like my arm was going to be cut in half.
There is definitely a difference in the procedure being used, which I believe would affect anyone. Any thoughts?
The technique used to obtain blood pressure must be correct, or the blood pressure reading can be erroneously high or low. Many readers have written in over the years noting mistakes commonly made in checking the blood pressure in the office.
The cuff should be inflated to about 30 points higher than the expected blood pressure, which can be estimated by feeling the pulse when inflating the cuff. The size of the inflation bulb, the size of the cuff and the size of the arm all determine how many times the bulb needs to be compressed to get to the correct inflation pressure. If the examiner doesn’t inflate the cuff high enough, the measured blood pressure will be much lower than the actual blood pressure. If the cuff is inflated too high, it can cause enough discomfort and anxiety in a patient that the blood pressure can temporarily go way up. I wonder if this happened in you.
In absence of anxiety or pain, the cuff can be pumped up to 300 mmHg and it will not affect the measured blood pressure, but it’s unnecessary to pump it so high.
The other commonly made errors in checking a blood pressure include: using the wrong cuff size for a person’s arm; errors in patient position — the patient should be seated with support for the back, with legs uncrossed and resting on the floor; and errors in deflating the cuff too quickly (2-3 mmHg per second is best, and much slower than many people do). There are other considerations as well. The room should not be too cold, the patient should not be talking, caffeine and smoking should be avoided in the hour or so before the test, a person should sit quietly for at least five minutes before the test, and the cuff should be on bare skin, not over a shirt or, worse yet, a thick sweater. Checking blood pressure several times (I was taught always to use the average of three readings) reduces random error.
I don’t discuss topics that may lead to anxiety prior to checking blood pressure. This especially includes a person’s weight.
Since a high blood pressure diagnosis often means lifelong medication, taking a few extra minutes to be sure of correct technique is critical. Alternatively, 24-hour blood pressure monitoring with a device has been shown to be a better predictor than office-based measurements. Finally, an accurate, certified home device makes it easier to get many readings, which can lead to better decisions.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu