Dear Doctors: I have read that for an accurate blood pressure reading, you should first sit in a comfortable chair with no talking or distractions for at least five minutes. But my doctors all slap on a cuff, ask questions the whole time, then exclaim that I have high blood pressure. I have to ask for at least five minutes of quiet before a reading. How do we convince doctors to change?
Dear Reader: A doctor's office is an artificial environment. Many people have fought through traffic, and perhaps for a parking space, before they even reach the door. Then, in the waiting room, they are left to manage the anxiety that can often accompany a medical visit. In our opinion, the blood pressure readings taken when someone first sits down in an exam room, often while being quizzed about their medical history, are likely to reflect that person’s blood pressure under stress. That is why, in our own offices, we don’t make decisions about blood pressure medication based solely on a single office value.
You are correct about the optimal conditions needed to obtain an accurate blood pressure reading. In fact, they are used in the clinical studies used to arrive at standardized blood pressure ranges. As you mentioned in your letter, this includes sitting upright in a comfortable chair that supports the back. The arm needs to be supported at heart level with both feet flat on the ground. There should be a quiet resting period of at least five minutes before the test. And because blood pressure fluctuates, multiple measurements, several minutes apart, are needed for an accurate result.
Additional factors that affect blood pressure include time of day, temperature and exercise. Blood pressure is typically highest in the morning and lowest at night. Blood vessels constrict in a cold room, which can elevate blood pressure. Heat can do the opposite. The effect of exercise, in which blood pressure rises as the heart works to send oxygen and nutrients to the muscles, continues for at least 30 minutes after the exertion ends. Caffeine and tobacco raise blood pressure. So can certain medications, including over-the-counter pain relievers. Being dehydrated can cause blood pressure to dip. It is also important to use the correct cuff size. A cuff that’s too large can cause a false low reading, while a cuff that’s too small can give results that are too high.
Some people routinely have elevated readings in a medical setting, a response known as white coat hypertension. In those cases, we advise bringing a detailed log of at-home values to share with the physician. That information reflects a pool of data collected over time, and we find it to be a more reliable index than a single office-based reading.
Blood pressure is an important metric of health. We believe making medical decisions based on a single reading is unwise. And though we don’t have an answer about how to encourage systemic change, we applaud your approach of advocating for yourself. Patients feeling rushed are within their rights to request the same environmental conditions in which blood pressure standards were created.
(Send your questions to [email protected], or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
