Blood pressure monitor - Page 1
Forum section: electronics / projects

author: moffy
author_rank: Super Contributor
timestamp: July 30, 2018, 11:55:37 pm
content: Just found out I have hypertension, but am noticing quite a bit of variability with the automatic blood pressure monitors. From some reading I've done, the oscillometric (blood pressure machines) uses a little bit of guess work as to where systolic/dyastolic pressures are, also somewhere I read that the algorithms are considered proprietary. e.g. different machines, different results.Does anyone have experience in the area? When I go to my doctor this afternoon I'm going to ask him to take the measurement the old fashioned way (Auscultatory) with the stethascope. Look forward to your responses.

author: ataradov
author_rank: Super Contributor
timestamp: July 31, 2018, 12:05:45 am
content: I use "Omron 5 Series" blood pressure monitor and I get consistent readings from day to day. And the couple times I had a chance to compare it with doctor's measurements, the results were spot on.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 31, 2018, 12:17:26 am
content: Agreed. I have an Omron for easy monitoring. My personal physician has a different, commercial grade instrument. The commercial grade instrument is a little better (i.e., results are closer to auscultation), but he always does it by the "old fashioned" method for my chart. And I do likewise occasionally.If you want to DIY, you cannot use the cuff readings from the automated instrument, in my experience. There is some magic in them.* You will need your own cuff and stethoscope.John*You have probably noticed that you can get a good estimate my watching the pressure needle (or mercury column) fluctuations in real time as the pressure is released or just reading your own pulse during the deflation. My readings with a stethoscope and the readings on the automated device's screen at the time do not agree, but the final results aren't bad +/- 5 mm.

author: moffy
author_rank: Super Contributor
timestamp: July 31, 2018, 12:33:00 am
content: +/- 5mmHg is not bad, and the Omrons do appear quite popular. I had an experience recently though where at the hospital without any blood pressure meds I was getting 170/90 mmHg when I went to the docs a few days later after taking the blood pressure meds I got 180/100 mmHg, and it was an Omron, but I don't think series 5. Go figure.

author: moffy
author_rank: Super Contributor
timestamp: July 31, 2018, 12:38:26 am
content: http://www.cinc.org/archives/2015/pdf/1073.pdfThe article states as a conclusion that the:"More importantly, this study demonstrated thatauscultatory method is more stable than oscillometricmethod using the data from eight repeat measurements,and confirmed that the oscillometric method for BPdetermination based on characteristics ratios is notreliable enough for replacing the auscultatory method inclinical applications. "

author: G0HZU
author_rank: Super Contributor
timestamp: July 31, 2018, 12:44:59 am
content: I don't have 'high' blood pressure and I'm not on any BP meds but I have got an upper arm blood pressure monitor here at home.I think mine is the Braun Exact Fit 6000 series as per the link below. However, I don't know much about what tech it uses other than it is an upper arm model with fairly good (claimed) accuracy.https://www.braunbloodpressuremonitors.co.uk/product/braun-exactfit-3-upper-arm-bp6000/In my case I think I get a spread in readings because I hate using it because I don't like the sensation it gives in my arm. So I think stress contributes a bit to my readings. I can get anything from 125/78 to 138/90 on a typical test session of three readings in quick succession. I try and do my tests on a lazy Saturday morning maybe three or four times a year.My resting heart rate is good though. I can get below 50bpm if allowed time to lie down and relax a bit. Otherwise, it's usually about 60-64 if I lie down for just a minute or so.

author: moffy
author_rank: Super Contributor
timestamp: July 31, 2018, 12:54:37 am
content: Thanks for the info GOHZU. Impressive resting heart rate, but it's the variability in the diastolic that is most disconcerting. I ordered a manual blood pressure measurement device, so I guess I'll have to learn the manual technique as a reference. Have also ordered a VIVE automatic upper arm blood pressure monitor.

author: G0HZU
author_rank: Super Contributor
timestamp: July 31, 2018, 01:02:09 am
content: Does your pulse rate go up when you measure your BP? I try really hard to relax during the test but it always goes up to 70 or maybe even 80 bpm. I have one of the little finger pulse rate + oximeters and I use this before/during/after the BP test to check my heart rate.Is it normal/expected to see the pulse rate go up during a BP test? I absolutely hate the sensation it causes in my arm so I can't seem to relax during the test. I think many people take three readings and then average it. When I do this I typically get about 125/85 average. This is slightly above the 'normal' range but probably typical for my (older) age group.

author: moffy
author_rank: Super Contributor
timestamp: July 31, 2018, 01:12:40 am
content: It's called white coat syndrome i.e. doctor, but in your case I guess its just the anticipation, no white coat, unless you wear one while doing the measurement.I don't know about my heart rate but I feel pretty relaxed, no real anticipation. But my resting heart rate is 80 bpm, pretty high.

author: ataradov
author_rank: Super Contributor
timestamp: July 31, 2018, 01:38:24 am
content: I did a test of 6 measurements in a row. Same setup, same cuff setting, same pose. All 5 tests are performed in a row, basically as fast as was possible. Here are the results:111 / 72 / 56113 / 76 / 61107 / 71 / 60111 / 66 / 60104 / 66 / 58114 / 66 / 60I'm sure this is close enough for any practical uses. Why do you need to know it exactly. You really mostly need to know if it is much higher than usual / normal.

author: sleemanj
author_rank: Super Contributor
timestamp: July 31, 2018, 02:16:20 am
content: I have a cheap aliexpress automatic arm cuff, it works fine for what you need in a home measurement device. Pretty much everything affects your blood pressure anyway, stress, posture, food, time of day, fullness of bladder... You want to look for trends more than individual results.I have however been advised by pretty much anybody in the know that the wrist cuff type measurements are not great.3 tests one after the other, same arm same posture129/74 / 90126/75 / 87128/74 / 83

author: Bud
author_rank: Super Contributor
timestamp: July 31, 2018, 02:17:52 am
content: Mine is funny in that when i take 3 consequtive measurements, the second and third ones are always less by about 5 units from the first one. It is almost like the squeezing action of the cuff during the initial measurement stabilizes my blood pressure.Interestingly, in a user manual of a higher grade device that i read, they say discard the first measurement and average the next three. Seems to make sense to me given my case.

author: Bud
author_rank: Super Contributor
timestamp: July 31, 2018, 02:22:32 am
content: One thing is for sure, from engineering perspective: he who will design a accurate BP monitoring non-invasive method and device, will become a millionaire.

author: 2N3055
author_rank: Super Contributor
timestamp: July 31, 2018, 07:28:42 am
content: Quote from: Bud on July 31, 2018, 02:17:52 amThere is an actual recommendation not to take rapid consecutive measurements because of the compression effect... You should make 15-20 min pause between measurements... But for general "do I have high blood pressure" checks it's ok. Upper arm measurements with good modern automatic device will all yield good results. Wrist ones are not very reliable.

author: darrellg
author_rank: Unknown
timestamp: July 31, 2018, 04:47:54 pm
content: Wirecutter has an article about this:https://thewirecutter.com/reviews/best-blood-pressure-monitors-for-home-use/If you have doubts about the accuracy of your device, take it with you to your doctor's office and compare its measurement to theirs.

author: Bud
author_rank: Super Contributor
timestamp: July 31, 2018, 05:49:23 pm
content: well it is not only about technology but also about the procedure. i.e. any textbook will tell you have to rest that many minutes before taking readings, take a particular pose if sitting, and things like that. When i am taken BP measurements at my doctor's she violates every single of that procedural recommendations. So i am not holding my breath for accuracy of her measurements and only treat them qualitatively. The difference is still big enough compare to my readings at home. And i use my wife as the Calibration kit at homeso i know i am a bit on a high side number-wise.

author: Bud
author_rank: Super Contributor
timestamp: July 31, 2018, 05:55:44 pm
content: Quote from: 2N3055 on July 31, 2018, 07:28:42 amThat seems to be a bit of overkill. I do not think Anyone does that. From experience, 2 min and a few deep breaths is suficcient to restore the blood flow.

author: moffy
author_rank: Super Contributor
timestamp: August 01, 2018, 11:45:18 pm
content: Thanks for all the feedback, very interesting. I agree the wrist ones are not as good as the upper arm.I visited the doctor two days ago and I had the nurse do a manual test, she also used what looked like a hospital grade automatic machine by Welch Allyn, then 10 mins later the doctor took my blood pressure with his Omron.The results:Manual: 150/90 mmHgWelch Allyn: 145/93 mmHgOmron: 160/100 mmHgThe difference between 150/90 and 160/100 is significant, and from what I've read the automatic meters are better at some blood pressure ranges and not others. The standard still seems to be the manual method.

author: jpanhalt
author_rank: Super Contributor
timestamp: August 01, 2018, 11:54:00 pm
content: @moffyThis may interest you:https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/diagnosis-treatment/drc-20373417

author: moffy
author_rank: Super Contributor
timestamp: August 02, 2018, 12:02:54 am
content: Thanks jpanhalt, it is a comprehensive article and I had read it before. It is very thorough.