I just donated blood this afternoon, and my experience there has inspired me to ask a question I’ve wondered about for a long time. Do health care practitioners sometimes have a pre-conceived notion about what they think a patient’s blood pressure is going to be, and can this have an effect on the blood pressure reading that they end up putting down on the chart?
I am overweight, and I have the distinct impression that with many health care practitioners there is an assumption that overweight => high blood pressure. As a general rule, my blood pressure is on the order of lower 120’s over upper 60’s to lower 70’s. Frequently, though, I see nurses or others taking a blood pressure reading with methods I find questionable, and when they do, I typically end up with a higher than normal blood pressure reading for me. Is it possible that I am sometimes a victim of stereotyping, and end up with an inaccurate reading based upon what the examiner feels my reading OUGHT to be?
Although I don’t have a medical background, I did take a First Responder’s course in college, and as part of that we were taught how to take a blood pressure reading. We were told the person should be seated and relaxed. Preferably, their arm should be supported. We were told to pump the pressure in the cuff up to about 200 (or at least 10 above what their expected systolic reading should be, if we knew that.) At that point, the valve should be opened just enough to release the air and drop the pressure at a prescribed pace. I was taught that once you open the valve, you should NEVER stop mid-reading and pump it back up again. The point where you can first hear the blood flow at the brachial artery is the systolic pressure; the final point at which you hear it is the diastolic pressure. I was told that if you didn’t get a good reading, you should deflate the cuff and wait at least a minute or so before trying again.
Today, however, bloodmobile guy puts the cuff on me, pumps it up to 210 or so, and opens the valve. As I usually do, I watch the meter on the wall, and see the needle smoothly descend until it gets to around 120 or so, where I see a little jump in the needle. From there, I see the needle continue to descend, complete with the little jumps. Once it gets below around 90, I see bloodmobile guy remove the stethoscope from beneath the cuff and his ears, but I still see the needle moving steadily, with periodic jumps until it gets to around 70 or so. When he finishes, he writes down my BP as 120/90.
Now, since I can’t hear what’s going on in the stethoscope, I can’t know for sure what he can or can’t hear. Does my visual observation of the continued jumping of the needle mean that the true diastolic pressure hadn’t been read yet, or is that just something that will happen anyway?
As I mentioned earlier, this is not an isolated instance. This frequently happens to me with nurses in doctor’s offices, where I see them stop listening once it gets below around 85 or 90. Another thing that frequently happens is to see the nurse stop midway, before getting a diastolic reading, and pump the cuff pressure up to 200 again. I have even had this done as many as 3 times in a single reading before. (And yes, my arm sure was tingling by the time they finally got done.)
Am I getting an accurate reading with these techniques, or is it possible I being given an inaccurate reading due to pre-conceived expectations?