“I don’t get it! Everytime I come to your office my blood pressure is high. It’s never like that anywhere else!”
“White Coat Hypertension” is very common and affects many people, even those who feel at ease with their physician. But whether your blood pressure is low or high at the doctor’s office, if you’ve been told you might have hypertension, you are likely to find yourself at home, or in a grocery or drug store with your arm in a cuff trying to figure out if your blood pressure is reasonable. A key to successful self-measurement is knowing the proper technique.
The big studies of blood pressure in the population upon which we base all our definitions of normal and high values were careful to take their measurements in a standardized way. The patient should avoid coffee, tea, nicotine, and other stimulants for at least 30 minutes prior to the test. She should sit quietly for a full 10 minutes reading or softly conversing before measurement. Even reaching across the table to pull the BP cuff near is to be avoided. (Get the machinery next to you when you first sit down.) Use an upper arm cuff. Forearm and finger devices are not reliable. Feet should be flat on the floor, clothing comfortable, and a bare arm may be needed for some machines. Two or three measurements a few minutes apart may be averaged.
A few caveats to mention: if one arm is higher than the other, you have to go by the higher side. Humans have a natural ‘diurnal’ variation, with most of us having a little higher blood pressure in the morning compared with later in the day. Blood pressure rises with physical and mental exertion and takes some time to come down, so don’t expect a resting value if you’ve not been at rest for 10 minutes or more.
Blood pressure is dynamic and always changing. The majority of values should be in a good range; your physician can help you determine if your numbers are in the range you need for optimal health.