Blood Pressure and Preconceived Expectiations

Factual Questions
1

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?

2

Alright, real fast:

You can auscultate (hear with a stethescope) the systolic (upper number) but not diastolic. Even when the vein is always open, not flapping, and not making noise, it still causes pressure variations. So, it could still all be legit.

Yes, people that aren’t very confident in their BP skills will often alter their results, a little or a lot, to be in line with expected results. If you want to remove the human element, many if not most hospitals now have electronic BP measurment systems.

3

I have been in situations lately where I had to go to several doctor’s appointments on the same day over several weeks. I have encountered several nurses that have a bias one way or the other. Each of these nurses is very consistent with their readings but they differ from each other by about 30 + or - points from each other. I was skeptical of this so I brought my electronic blood pressure monitor from home, left it in my car, and checked it after the appointment. Each time, it was where it should be and very different from the reading they just took.

Is there any reason why all doctors and nurses don’t use electronic blood pressure monitors? Many of them do so it can’t be any big disadvantage.

4

(My Bold) Really? :dubious: Then what, pray tell, have I been hearing these past 40 years?
I was taught proper blood pressure technique by one of the premier nephrologists in the country.
Her feeling is that health care providers miss the change, because they use the diaphram side of the 'scope. The diaphram side is for higher pitched sounds, The sounds heard when taking blood pressure are low register sounds, so, the bell side of the 'scope is the appropriate tool.

YWalker Indeed, there are providers who “pencil whip” vital signs. Whenever you feel the reading isn’t right, tell the doctor, and if necessary, the clinic supervisor. The people who take your blood pressure at the doctor’s office aren’t nurses, and may need a refresher. Unfortunately, its often laziness.
The main reason the digital blood pressure monitors aren’t used is cost. The one you have at home is fine for using a couple times a day, but the ones clinics and hospitals have to use have to be sturdy enough to handle dozens of readings a day.
They can be inaccurate as well. They should be calibrated about once a month, but rarely get it more than once a year. Also, the provider still needs to place the cuff on properly, or get a false reading.
Also, they are something new to learn. Older docs often don’t trust them. The newer ones are much more reliable, but, change is hard.

Shagnasty I have no doubt you saw a pencil whipping or two, as well. However, your BP could easily be higher when you’re up on that cold, vinyl exam table.
If you question their findings, take your cuff in with you and have them use it. Remember, you are the most important member of the medical team that cares for you. You must advocate for your own good health.

5

I’m having a hard time finding the study now, but it’s been shown that electronic blood pressure cuffs are inaccurate in hypotensive patients and particularly in trauma patients. When I have occasion to use a the NIBP monitor (usually just on the Critical Care unit) I don’t trust it until after I’ve already aucultated a pressure. If it’s close great, if not, then it’s not useful.

Also, needle bounce is not a very good way to determine a blood pressure. It’s sometimes close, but it can vary widely from what the actual readings are.

St. Urho
EMT-P

6

I have a high BP so I get mine taken quite often. With a little practice you can quite accuratly determine your own BP when the doc/nurse/technician takes it. When the cuff is being inflated you should notice that at some point you can feel the pulse in your arm quite distinctly. Remember that feeling. As it is further inflated you will again lose the ability to feel the pulse. As the cuff is deflated watch the needle/mercury/digital display and note the point where you once again feel the pulse - this is the systolic reading. Keep watching the reading as the cuff is further deflated. At the point where you can no longer feel the pulse (IME this is a little more tricky as it has a less distinct cut-off) you have the diastolic.

There is also something known as White Coat Syndrome. This is where your BP rises in anticipation of having it taken. In my case my BP tends to be higher when taken by somebody I have not met before and gradualy reduces as I get used to them.

7

Thanks very much for your feedback, threemae, Shagnasty, picunurse, St. Urho, and ticker. (And I thought it was hilarious that someone named ticker was the last poster to a thread on blood pressure.)

Thanks for introducing me to the term “pencil-whipping”, picunurse. I think that’s a perfectly descriptive term. Since this particular reading was just a formality to prove I was safe to donate blood and won’t go on my chart, I didn’t think it was worth quibbling over. I may start commenting when I see this in the future, though.

A followup question: When the BP-taker pumps you up to 200, releases, then pumps it back up again and releases a couple of times before taking the reading, could this artificially induce a higher systolic reading?

Thanks for describing this more accurately than I did. I get doubtful about the diastolic readings I get sometimes because not only can I continue to see the needle jump, I can also feel the pulse in my arm for a couple of beats after they’ve already pulled the stethoscope out and started writing down the number.

I have mixed feelings about the electronic monitors. I realize that they’re more objective than a person, but, as an engineer, I know they’re fully just as capable of creating crap readings. I think the combination of a person and electronic monitor would give the most accurate results. (I’ve also been terrorized by a rogue monitor in the past that was left to monitor me at set intervals. Instead of “learning” my previous readings and adjusting its pumping levels, it would pump me up to about 250, and sometimes re-pump before ever releasing all the air. It was more a tourniquet than a blood pressure cuff.)

8

I have seen the OP in reverse. Some years ago when I was still a heavy smoker and was hospitalised, the nurses would routinely look at my obs and want to change my history because my blood sats were “too good for a smoker”. They were very keen for me to admit that I didn’t really smoke, but I did.

9

Blood pressure is one of the most frequently misperformed aspects of a basic physical examination. A lot of people can’t even pick the proper size blood pressure cuff, and wind up eyeballing it. You shouldn’t smoke or drink coffee 30 minutes before the reading.

What other people have said is pretty much correct, although I’m not sure if people can feel their own BP accurately. I’ve seen enough to buy that some people can. With regards to the re-pumping of the cuff, this can be an appropriate measure IF you’re palpating to determine appropriate systolic start pressure - you take the radial pulse and inflate the cuff until the pulse disappears and add 30mm to it - that’s your new ‘start’ pressure. It means not having to over-inflate the cuff and cause the patient discomfort that’s unnecessary.

You now wait about 30 seconds (with cuff deflated) and then pump to the new start pressure and release pressure slowly, listening for the first period where you hear two consecutive beats. (You might have one beat beforehand - record that and note the ascultatory gap). You listen down until you hear muffling of the Korotkoff sounds, and shortly thereafter they will disappear. The disappearance point is the best estimation of diastolic pressure; technically you can’t “hear” diastolic pressure, but it amounts to the same thing as the last beat you CAN hear before disapperance.

A good practicioner will listen carefully for another 10 or 15mmHg to ensure that they aren’t missing a further muffled beat, and finally deflate rapidly to zero. Other little details are taking it while the patient is relatively relaxed, at least twice in each arm on the first visit (if you’re a GP at least) before making a definitive diagnosis, and taking it at least twice in each visit unless readings are normal.

There is a lot more nuance to it than that, but expert practioners who are being CAREFUL can still take a pressure very, very quickly. Doesn’t sound like that’s what is happening in the OP. You’re getting improper care, YWalker. Ask for a do-over. :slight_smile:

10

Excellent post, don’t ask. Are you SURE you’re really a smoker? :wink:

Thanks very much for your response, BoonDoctor. Do you think it would help any if, when they put the cuff on, I say “I’m usually somewhere in the neighborhood of 120/70?”

(Oh, and regarding cuff sizes — I’ve always just seen them grab the one that happened to be in the room. The only time I’ve seen a change was when I had mild pregnancy induced hypertension during the last month of my first pregnancy, and the midwife used a larger cuff to give me the benefit of the doubt. She also went out of her way to get good readings, by taking multiple readings during the visit, while standing and lying down, etc.)

I hope you decide to stick around a while, by the way.

11

Well, it might help. Although if your health care provider is rushing the measurement that much it’s probably going to go in one ear and out the other. It might be easier to question the reading afterwards. Pretty lame that they didn’t comment on a 90 diastolic pressure, either. That should be reason enough to repeat the measurement.

Sadly, it won’t happen. I don’t use these boards enough to bother, and I liked it much better when it was free. The poor student in me doesn’t like paying for stuff I don’t use much. Thanks for the kind words, though. :slight_smile:

12

Damnit, I meant palpate the diastolic.

Also, that bell vs. diaphragm bit is correct.