Have you ever been to a "Guess your age" booth at an amusement park? If you are able to fool the person guessing the age of passers-by within a couple of years you win a stuffed animal or toy. Well believe it or not, clinicians occasionally do this to their patients. Not for age, but for blood pressure. Glenn Nyback, an EMT teacher, recounts a personal experience from one of his classes:
As a female student was measuring the blood pressure of a 23-year-old classmate, we noticed that she took his pressure over and over. Then, with a puzzled look on her face, she said to us, “Could one of you check this? I don’t think I’m getting his pressure right.”
The student did what the age guesser does taking visual cues to make an educated guess about a factual characteristic of the subject. And just as the age guesser can be wrong at times, the student's guess was wrong in this particular case. From sight, a young, fit-looking person should probably be normotensive, about 120/80, but not the 180/114 BP that was measured. Nyback places some context to the situation explaining that with the right information, the puzzle is solved and everything makes sense again.
He (the 23-year-old classmate) then went on to say that he wasn’t really surprised about it, since most of his older family members had high blood pressure (aka hypertension).
Nyback illustrates a situation that actually happens in clinics with patients. Whether it's a clinician or a blood pressure monitor that takes the initial measurement, seemingly-odd values like 180/114 are not always inaccurate. As in this case, they can be truly accurate and need prompt clinical attention. The gold standard to confirm a patient's BP is careful patient preparation and thoughtful technique.