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How accurate are blood pressure monitors?

C

Cowboyjim

Well-Known Member
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How accurate are home blood pressure monitors vs the GP's monitor?
A mate of mine just found out his home meter was out by 15 points compared to that of his GP. This is about 10% or so. But which is in error? Maybe both are?
I know I can calibrate my glucose meter but am not aware of a simple accurate way to check the BP. He wants to know because of the acceptance threshold for the services.
All comments gratefully received.
 
The only way to check as far as I know is at roughly the same time on the same arm against an experienced operator with a mercury-in-glass sphygmomanometer.
 
Thanks for that. I wonder who checks the mercury one then? No measurement equipment can be deemed accurate in absolute terms unless it is measured against a standard. This should be regularly checked.
I think he experienced something like this today, will report back.
 
Cowboyjim said:
Thanks for that. I wonder who checks the mercury one then? No measurement equipment can be deemed accurate in absolute terms unless it is measured against a standard. This should be regularly checked.
I think he experienced something like this today, will report back.
Click to expand...

There is nothing to calibrate in the mercury job as its just a long 'U' tube that is read off against a fixed scale.... I've got one here somewhere (probably with the stethoscope), but the self inflating electronic job is so much quicker and far less bulky for a quick daily check.
 
If he checked his meter against the GP's by doing his own test just before going in for the GP test, it could well be 10% different - white coat syndrome will account for that. I get that all the time. Bet the GP administered one was higher!
 
I have often wondered about the exact process used by doctors and nurses to take blood pressure. It just seems a bit ad-hoc in the modern digital age. I wonder whether the rate at which they let the bag deflect and the exact timing are of any relevance as it all seems to be experience and technique to the untrained eye.

I also thought that the patient needed to be relaxed and calm (at the gym they make you sit for five or ten minutes and won't do it after you have started exercising) whereas I've had mine done at the surgery at all sorts of points, including in the middle of a "difference of opinion" half way through the consultation and after a morning at the gym. (highest ever reading for me).

I take mine at home and it's not a million miles away from what the nurse gets. Admittedly, I now ask her to do it at the beginning of the appointment before anything else and I've usually been waiting five minutes beforehand.

Does anyone know more about this subject who could enlighten us?
 
I've been having investigations and treatment for very high blood pressure. I am having to monitor my blood pressure at home and have been seeing my GP or a nurse every week for the last few weeks as well. The majority of the time my readings have been very close to those that the GP and nurse have got. If my blood pressure has been higher than the gp or nurses last recording then i have had to wait 5 minutes and have it taken again.

A 24 hour blood pressure recording also showed results close to what i was getting myself at the time. When i had a stress (treadmill) test, i had to be taken off early as my blood pressure was going sky high.
 
Thanks for all the comments and very sorry to hear that Claire. Hope they can do something for you ASAP.
Dunno why but I get so rattled when in the GP's. Maybe having to sit in the waiting room for ages with all the usual types, the vacuous muzak on local radio, ****** mags, screaming kids, etc has something to do with it.
My mate does not seem to exhibit white coat syndrome nor do my kids thankfully. I like to think I am not scared of anyone but my BP says otherwise.
Mind you, when you are in there discussing DM and the NHS policies on it one's blood can start to simmer...8)
 
Cowboyjim said:
I like to think I am not scared of anyone but my BP says otherwise.
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Not to do with being "scared" neccessarily. Just thinking "hope it's o.k!" is enough. part of the flight or fight syndrome. BP goes up before a fight as well as a flight!
 
Emphasis on the 'or' in fight or flight then.

Also I often feel myself wanting to 'do well'. An odd notion that I hate. Whatever the case it is a stress factor that Heisenberg would no doubt find amusing. 8)
 
Cowboyjim said:
How accurate are home blood pressure monitors vs the GP's monitor?
A mate of mine just found out his home meter was out by 15 points compared to that of his GP. This is about 10% or so. But which is in error? Maybe both are?
I know I can calibrate my glucose meter but am not aware of a simple accurate way to check the BP. He wants to know because of the acceptance threshold for the services.
All comments gratefully received.
Click to expand...

It's also important to note you can not calibrate you glucose meter!! The control solution just checks the meter is working within acceptable tolerance

For example if I use the control solution on my accu-chek I should get a reading between 1.7 and 3.3 that is quite a variance.... But if the result is outside that range either the meter or strips are faulty, you can not 'calibrate' to bring it within range"
 
I check my BP meter with the docs at the hospital and I assume hers is checked periodically.
I was quite surprised that mercury sphygs are still used. I haven't seen one since I left the UK and I know they use digital ones on the wards in my parents local hospital.
(I looked it up then and it seems that they are still sold in the UK (presumably to GPs) but banned in many other parts of the Europe )
 
Oh dear. Another assumption wrong - re glucose meter calibration. Such a range is indeed worrying. I have always had this suspicion about the error in these gadgets. I used to do a lot of lab measurements - in physics not bio - and 'drift' we called it was a major concern. One of instruments had to be cal checked twice a day.
I suspected that these little meters built for a price would not be accurate for long and yet we build our lives around them. It is almost not worth thinking about....
Maybe some are more reliable than others. Maybe none are. Maybe some are ok when you buy them but I have had mine for over a year. Should I get a new one?
It also worries me that I will not be able to find anyone in the NHS with a clue.
Beginning to wish I had not posted this question. :(
 
Cowboyjim said:
Oh dear. Another assumption wrong - re glucose meter calibration. Such a range is indeed worrying. I have always had this suspicion about the error in these gadgets. I used to do a lot of lab measurements - in physics not bio - and 'drift' we called it was a major concern. One of instruments had to be cal checked twice a day.
I suspected that these little meters built for a price would not be accurate for long and yet we build our lives around them. It is almost not worth thinking about....
Maybe some are more reliable than others. Maybe none are. Maybe some are ok when you buy them but I have had mine for over a year. Should I get a new one?
It also worries me that I will not be able to find anyone in the NHS with a clue.
Beginning to wish I had not posted this question. :(
Click to expand...

Home glucose meters are on really intended as a guide, and if you check it with the control solution every now and the it just confirms the meter is not too far off

This is one of the reasons you will see many posts about people with 2 meters testing from the same blood sample and getting quite different results, so the general response is just use 1 meter

I think the main point is it will be in the right ball park, face it, millions of people use them every day and the control is better with them than it was with the old colour dip strips

Don't let it worry you too much :-)
 
In any case I measure blood pressure at least two times within 5 minutes period of time. It is easy but prevents from totally inacurate results...
 
Blood pressure varies from second to second and depending on your mood, so it's far more prone to variance than blood sugar, though that can change in s matter of minutes.

I'm 20 my last reading was 158/85 and clearly they weren't worried because they must think it would go lower later because blood pressure isn't very constant.


Sent from the Diabetes Forum App
 
Yes blood pressure can be a bit of an unsatable one. You will find that as stress goes up so will the blood pressure (as mentioned above). Also trying to relax and take a few deep breaths before taking the reading can make it lower, there is also the fact that actually taking the blood pressure readings causes a stress response in the body and artifically increases it.

Also being active in terms of exercising and spots will lower it. One other thing I have noticed is that if your blood glucose is high or you are having a hypo this will rocket your blood pressure (specially when the insulin is in process of lowering the highs and distributing the energy about your body).

Just don't let it worry you too much, if you do it will stress you out and make it worse.
 
Both my boyfriend and mother have extremely high BP and have been issued with monitors to take their BP 4 times daily.
Mum's GP uses the home readings as well those taken in the surgery as guidance for treatment, however BF's GP states that he doesn't take home readings into account as the monitors are completely unreliable - seems a bit pointless issuing it then?
Like others, his readings are very different in the surgery; sometimes higher, sometimes lower.
Personally I use the kit available in local pharmacy and also the monitor in GP's waiting room and they seem to correlate so I trust them.
 
Hi, GP monitors aren't that accurate as depends on how often they're calibrated. Also depends on what make the surgery uses as my surgery have same one i bought for £15.! Last time i got mine checked at surgery the healthcare assistant told me my reading was high. Its never been high on my machine & as I work in a hospital i check mine regularly on machines there & havent had a high reading yet.! The manual monitors that involve using a stethoscope are more accurate & the mercury ones are mainly banished due to obvious mercury content.
 
Forgot to say, if you're checking your own blood pressure then the left arm is the most accurate as closer to the heart.
 
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