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There's definitely a huge variance in blood pressure readings depending on posture, relaxation, arm position, recent activity, etc. If you buy a blood pressure

There's definitely a huge variance in blood pressure readings depending on posture, relaxation, arm position, recent activity, etc. If you buy a blood pressure monitor, it's really interesting to see how "random" a single reading at the doctors' is, and how large your fluctuation throughout the day is. That being said, it really makes me wonder about studies that correlate blood pressure with other things. Is the blood pressure really being measured "correctly" in all those studies? Or not? In other words, if your "true correct" blood pressure is lower than what the doctor normally takes, but then a lot of the studies are based on real-life "incorrect" higher blood pressures, then don't you similarly want an "incorrect" higher reading for consistency? Or are the studies always really done with far more accurate blood pressure readings, where the patient sits still for 5 min beforehand, keeps their legs uncrossed, is totally free of stress and anxiety, didn't exercise beforehand, etc.?

gklitz 2y ago
> Is the blood pressure really being measured "correctly" in all those studies? Or not? This is why you do readings three different times a day for several days. And why there’s instructions on how long to dust still before the readings, why you do three repeats with multiple minutes of wait in between, and finally why the averages of those readings aren’t just simple averages. But yes you always have to wonder about every study using self reported home readings if they follow the instructions or not, because it is tedious to do it correctly.
- moffkalast 2y ago
  The reading process itself is a constant that you can't filter out by doing it repeatedly. Something squeezing your arm with what feels like the force of a hydraulic press surely doesn't have any weird side effects. Anecdata, but I always get high anxiety from not being sure if the thing is actually still working properly or if it's just gonna keep pumping itself up until it explodes in my face or something. Not exactly rational but these sort of things never are. Looney toons ass machine.
  - giantg2 2y ago
    "Something squeezing your arm with what feels like the force of a hydraulic press" It shouldn't feel that crushing. I know it's common, but it shouldn't be. It's lazy/rushed healthcare professionals who only want to take it one time suing an automated machine and crank it to 200mm. If you actually put it at 140mm or take it with a manual sphig, it would read a "normal" person just fine without the crushing. The problem is, the people who are high around 130-140 need the machine at least 20mm higher and would need a retake, which means more time.
    - SilasX 2y ago
      I have an automatic at-home blood pressure device, and it does the same thing. Not 200 mmHg, but high enough that I’d freak out if I didn’t know it was normal and would let up soon enough[1]. Did the product designers do that intentionally while still meeting a spec of “not panicking the user in a way that would elevate blood pressure” and getting approved for sale to non-professionals? It seems like this is genuinely hard to work around in practice. [1] I recall it being a staple of 80/90s tv, at least Beavis and Butthead, to have a character use an auto blood pressure device and freak out at being so clamped.
      - HPsquared 2y ago
        There might be a repeatability thing. Always give the full pressure then at least it's one less variable to account for.
        epcoa 2y ago
        Nah. Modern automatic cuffs are adaptive. They tend to first run up pretty low (like 150), see if there is signal. If not then they have to inflate more and more. They tend to determine where to start next time based on the last reading, so if it had the go up to 200 for the last reading it’ll start there next time. If the cuff is a vise, excluding operator error the most likely cause is actually having high blood pressure.
- hirvi74 2y ago
  > This is why you do readings three different times a day for several days. What good is this if my monitor is not as accurate as the one at a doctor's office? It's not like my doctor would take my monitor's readings over his.
  - devilbunny 2y ago
    You might be surprised. "White coat hypertension" is well-known. Someone with a reliable set of readings from home would be more convincing than someone who says "I get it read at Walmart/CVS once a month and it's ok". Your doctor's office's monitor isn't incredibly accurate. If you want accurate, you need a mercury sphygmomanometer to measure the pressure. Unless fundamental properties of the universe have changed, it will also be comparable to any other readings taken with mercury.
    - bigmattystyles 2y ago
      And it has to be in retrograde.
      - devilbunny 2y ago
        That's a complicating factor, but one that we can usually calculate.
  - coatmatter 2y ago
    Find one that is accurate enough and crosscheck it with the one at the doctor by taking regular measurements so you get an idea of trends rather than absolute values. Doctors do know about white coat hypertension - it's not a myth. There's no reason you can't do your own experiments with consumer-level blood pressure monitors from reputable manufacturers. In fact, it was my mother's primary care provider who recommended she buy one for home use. This is what I did with a US$10 pulse oximeter (a Contec CMS50M from China) when my dad ended up in ICU last year, and it was pretty much bang-on with its readings. I've also tested my pulse oximeter on plane trips and know it will drop below 90% when the air is thin (and rise up again if I do some deep breathing), and therefore know it isn't always stuck at a high value. Search PubMed for "The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by the Food and Drug Administration: The Possible Global Public Health Implications".
- kbelder 2y ago
  I would trust the self-reported home readings more than those taken by professionals, because they're probably happening more often and under less stressful and exceptional circumstances.
hombre_fatal 2y ago
As long as blood pressure variance is randomized then you’re getting a signal, and that happens when everyone is measured in a similar way (or randomized to different ways). You don’t need perfect precision. What you don’t want is to make everyone who, say, smokes wear the cuff while standing up while everyone else gets cuffed lying down.
- crazygringo 2y ago
  > and that happens when everyone is measured in a similar way (or randomized to different ways) But that's exactly the issue -- that the similarity or randomness is one way for one study, and another way for another study, because of culturally different sets of nurses and/or patients. In other words, you're right it's not affecting results within a study, but it makes comparison between studies questionable. And it makes it equally questionable whether a study's results apply to you, if your signal is 10 units off of a study's signal, and occurs across a cutoff that determines whether you should take a medication or not.
Mathnerd314 2y ago
I guess it depends on the study. If it is just comparing between groups, the conclusions probably still hold if they consistently measured blood pressure in the "incorrect" way. If it is something like "85% of Americans have high blood pressure", then probably the conclusions are incorrect because they are comparing the "correct" baseline against an incorrect measurement method. There are also other ways to measure blood pressure, like recent smartwatches - so read the methods section carefully, I guess.
hluska 2y ago
When my heart went to hell, I bought a blood pressure monitor. Before I left the hospital, I had to agree to religiously test my blood pressure three times a day at the exact same time. Anything beyond that was a bonus, but to provide useful data I needed those three readings a day. As my cardiologist explained, 39 year olds don’t randomly end up spending a week in a cardiac ward so he needed better data to form a holistic treatment plan.
ajuc 2y ago
My wife had a Cryo Chamber Therapy for a few weeks and had to measure pressure and pulse before each session so they let her in. After about a week she was refused entry because her pressure was too high (when she measured it at home - it was normal). Since then she had problems getting admited every time, and she started to fear the measurement (she had to drive there during work and do overtime later). She started arguing with the guy and wasted like 5 days driving there and back during work without having another session because the pressure and pulse were too high (despite both being OK at home). Eventually she went to another person in that hospital to measure her pressure. It was perfect. But when the guy near the entrance to the cryo chamber measured it - it was too high to let her enter. They tried different instruments and the difference was the same. When the guy measured it - it was too high. When somebody else measured it - it was fine. Finally they let her do the cryo chamber without the guy permission :) We assumed the difference was just that she was anxious and frustrated when she's seen the guy, but now I wonder if the difference was the position in which he measured the pressure.
- zifpanachr23 2y ago
  Had the exact same thing happen when I was doing a Ketamine therapy thing a while back, and I definitely think the anxiousness about the reading had something to do with it. I've always had perfectly okay blood pressure whenever I have it done at a regular doctor's appointment, so I think knowing that the reading actually matters definitely increases my blood pressure. Ended up getting a doctor's note saying "they don't actually have high blood pressure they are just reacting normally to possibly having to be sent home and reschedule" more or less.
  - joncrocks 2y ago
    I think this is a well-known thing, being apprehensive about having the measurement being taken can influence the result - https://en.wikipedia.org/wiki/White_coat_hypertension https://en.wikipedia.org/wiki/White_coat_hypertension
- running101 2y ago
  I get anxious when taking blood pressure as well. There are techniques your wife can try before entering the cryo-chamber look up the 478 breathing technique. I developed a white coat blood pressure readings over the last several years measuring a stage one or stage two hypertension at my last doctor visit. I use the 478 breathing technique and my blood pressure readings are normal at my last dr visit.
lysace 2y ago
I found that that the measured BP was consistently significantly lower if I didn't look at the device's display while it was doing it's thing. This at home, with a quality device, after doing it many many times.
- kyleee 2y ago
  Yes, i experiment with eyes open/closed as well
lottin 2y ago
Exactly, this is my concern as well. They say you have to be seated for 5 minutes at least, completely relaxed, not hungry, not having to go the bathroom, in a quiet a room, it must not be too hot or too cold, with both your feet on the ground, before you can have your blood pressure measured, otherwise the reading could be 'artificially' high. Really? It seems to me that if you do all these preparations, the reading will be artificially low, since such conditions are nothing like the conditions that you'll typically find yourself in through the day in your everyday life.
- BaculumMeumEst 2y ago
  The goal is to get a clinically relevant measurement, captured at rest under specific conditions, not a measurement that's representative of a random moment during everyday life.
  - saalweachter 2y ago
    We're also treating people for things like blood pressure somewhat statistically rather than individually. The studies say, people who have a blood pressure measured this way, that is above X, have an N% higher chance of dying M years sooner of A, B or C than people who measure under Y. If you treat with medication Q it lowers blood pressure, measured this way, by Z points, increasing lifespan by W QALY. Are you treating people who don't need to be treated and missing people who do? Could you achieve better results with continuous, invasive blood pressure measurements while the patients engage in every day life? Probably, but then you're increasing the cost of both the study and the public health intervention exponentially for gains in the margin.
  - lottin 2y ago
    But if the measurement isn't representative of your actual blood pressure what's the point of taking it? It's completely non-informative. Another problem is that even under very controlled conditions, I sometimes find big differences in blood pressure from one minute to the next.
makeitdouble 2y ago
Reading around (e.g. [0]) it sounds like variance isn't something researchers care for, probably with the assumption that screening with a higher value is better than missing an issue from a lower value. We see the same for body temperature (speed and convenience is usually prioritized over accuracy) and weight (2% variation is largely accepted). Afterall guidelines are already off as by definition, as they don't account for individual circumstances, so perhaps aiming for accuracy is useless in most settings. [0] https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/diagnosis-treatment/drc-20373417 https://www.mayoclinic.org/diseases-conditions/high-blood-pr...
SV_BubbleTime 2y ago
My doctor was handing me, hypertension, pamphlets, and talking about medication. Finally realized, that I was habitually late, getting to my appointments and always taking the stairs. Don’t do that.
- scottmf 2y ago
  iOS voice dictation?
  - SV_BubbleTime 2y ago
    Yea. But it’s mostly good except for the commas
    - scottmf 2y ago
      Haha, no I agree, but it was immediately, recognizable :)
  - mh- 2y ago
    With pauses to keep his BP low.
arcticbull 2y ago
Also doctors and nurses are known to do an abject awful job of measuring bp according to the defined procedure. It’s usually way off when taken clinically. Ars article here but there’s plenty in pubmed too. https://arstechnica.com/health/2024/10/your-doctors-office-could-be-reading-your-blood-pressure-all-wrong/ https://arstechnica.com/health/2024/10/your-doctors-office-c... [edit] The prep guidance is… > You must not eat, drink, exercise, or smoke within 30 minutes of a reading. You must have an empty bladder. You must sit straight up in a chair with back support. Your legs must be uncrossed and your feet must be flat on the ground. The arm to be measured must be rested on a flat surface so that it is at the same level as your heart, not lower, not higher. You must sit calmly, without talking for five minutes to relax before the reading. When it's time, an appropriately sized cuff should be wrapped around your bare upper arm, right above the elbow; it should never be wrapped over clothing. At least two readings should be taken, with the average recorded. Ideally, readings should be taken in both arms, with the highest readings recorded. When was the last time you got it measured properly? Literally never for me in a clinical setting. I don’t know why they bother honestly.
- ericmcer 2y ago
  Probably never, I have really long arms and they usually take it just barely above the elbow also. I have always been on the higher end even when in my 20s and training/dieting for athletic events. Used to flummox me until I bought my own meter, they can be like $30.
- ttymck 2y ago
  And what's the typical variance (from "actual") for a "usual" reading?
  - arcticbull 2y ago
    Good question, for myself personally (anecdotally) I got systolic of 145-ish in the doctor's office and 120-ish at home. This was validated by a medical take-home 24h cuff.
  - matheusmoreira 2y ago
mgh2 2y ago
This is why it is better to take three measurements and do an average every time to minimize errors. The studies on correlation probably have a large enough sample size to become statistically significant - i.e. you have to read the "Method" section to find out how reliable it is, this requires certain kind of statistics and/or scientific background.
buu700 2y ago
Another fun factor I learned about five years ago is temperature. My gym was offering a complimentary fitness evaluation, which among other things included a blood pressure test. The trainer was horrified to see 140-something over something equally terrible, and started explaining how she'd have to refer me to a doctor and advise that I refrain from strenuous physical activity, until I showed her a report from my annual physical a few days prior with 106/70. Turns out that walking to the gym in shorts and a T-shirt in late January causes enough vasoconstriction to really screw with some measurements.
- coatmatter 2y ago
  I once had a similar high outlier blood pressure reading after a somewhat busy day followed by running through the city to my blood donation appointment. Who knew that BP is affected by external factors and doesn't stay constant throughout the day‽‽
  - matheusmoreira 2y ago
    Having a full bladder will raise your blood pressure.
    - ghastmaster 2y ago
      It raises my heartrate as well. I know my bladder is full many times due to the heartrate rather than feeling my bladder. I'm not sure if others notice this. I assumed without looking at the anatomy that the arteries to the lower extremities are under pressure from the bladder.
  - gcanyon 2y ago
    I had a similar trip to the blood bank once: I rode my motorcycle from Palm Springs to San Diego, straight to the blood bank, on a cold January morning. As usual, they took my temperature. It was 95-something. They said, "Are you feeling alright?" I said, "Sure, I should have worn better clothing for the ride down here, but I'm fine." They conferred, then took my cold blood :-)
  - 2y ago
Zenzero 2y ago
> are the studies always really done with far more accurate blood pressure readings, where the patient sits still for 5 min beforehand, keeps their legs uncrossed, is totally free of stress and anxiety, didn't exercise beforehand, etc.? In situations where blood pressure really matters, we aren't playing around with the cuff and hand positioning. The patient gets an art line.
- lazide 2y ago
  Oddly, at least a decade ago, at least one Bay Area hospital stroke protocol required manual BP readings with a sphygmomanometer. And the patient had an art line. Not sure if they didn’t have the equipment for art blood pressure or what, but good BP readings were important. And they had all the fancy equipment. Patient presented with an ischemic stroke, and was getting a stent + thinners, so anything problematic was likely due to something immediately life threatening. They didn’t want an automatic cuff system because it could cause something to burst with the pressure ramp up. At least that is what the surgeon said. Source: I was the EMT-B on his clinicals who stayed with the patient in the OR while he got stented and took readings every 5 minutes because none of the nurses were ‘current’ on the manual cuff. or so they said. I was pretty fresh, and was pretty good at it at the time, but I think they were just making excuses now haha. I held his hand through the procedure to help calm him down too, which seemed to help a lot. Patient 20 something that day. Emergency Rooms are quite an experience. I volunteered for Halloween Night, which added to it I’m sure. PS. Watching the Dr install the arterial catheter (or maybe it was a port?) in the ER was wild. Literal stream-of-blood-shooting-across-the-room-and-spraying-on-the-wall wild. Never seen anything like it before or since. I was glad I had my safety glasses on.
haldujai 2y ago
> Is the blood pressure really being measured "correctly" in all those studies? Or not? Probably incorrect in most studies, especially large population ones that influence treatment guidelines. It’s academic and doesn’t practically matter though. The pathogenesis of hypertension related disorders (kidney failure, heart failure, stroke etc) is well known. It’s not in doubt that sustained hypertension is bad, that there is increased risk with higher blood pressure and that patients with high blood pressure undergoing treatment suffer less of these bad outcomes.
wonnage 2y ago
Kaiser measures BP on every visit and arm position seems like the least of their worries: - no rest period before measurement - measured through a medium-thickness sweatshirt sleeve - cold hospital hallway - no back on the chair - no height adjustment on the chair - no real surface to rest your arm on (They usually use the handle of the equipment cart that the BP monitor is mounted to) - Zero attention to cuff positioning/orientation I've come in at 160/90 but went down to 120/80 after rotating the cuff 1-2cm and resting for a few minutes. Manual measurements from the doctor are usually more accurate.
EPWN3D 2y ago
Kind of wonder the same thing about BMI and water composition. Your body weight can vary by up to 10 pounds depending on how much water you're retaining. I've never been able to find information about the composition assumed or measured when coming up with BMI numbers. Granted I don't think the ultimate effect is huge, and you can eliminate it by weighing yourself daily and taking an average. But most people don't do that, and a spot-check at a doctor's office certainly can't do that.
- matheusmoreira 2y ago
  > I've never been able to find information about the composition assumed or measured when coming up with BMI numbers. BMI is just weight divided by height squared. No distinction is made between type of mass. Muscle mass, fat, bone, water? BMI couldn't care less. It sums all that stuff up into a single value. Think of it as a number that roughly correlates to disease. There will always be false positives and false negatives. False positives are acceptable. We want to minimize the number of false negatives. There are nearly ten billion humans on Earth. It is not possible to fully evaluate every single one of them. Gotta run a SELECT statement. Filter them based on some criteria, and fully evaluate those that match. BMI isn't perfect, but it takes less than one minute to measure the variables and compute it. The equipment required is cheap and easy to use. Speed, efficiency, cheapness and ease are extremely important factors when you're applying this at national scales. Patient might turn out to be a physically fit 100 kg 1.7 m 34.6 kg/m2 body builder. That's alright. Our objective is to make sure the obese and the malnourished can't escape the sieve.
  - blitzar 2y ago
    You could probably get to a better generalisable number by slapping waist circumfrence in there as well.
    - matheusmoreira 2y ago
      Absolutely. Waist circumference should be and is considered as well, especially when evaluating obesity and its comorbities. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027970/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027970/ The combination of BMI and waist circumference is even better.
andreareina 2y ago
My understanding from people who follow the literature is that the studies are done with the recommended procedure, 5 minute wait and all.
lo_zamoyski 2y ago
Yes, I was thinking the same. If everyone is measuring heart rate under similar conditions, and then correlating that heart rate with other factors, is that perhaps alright? Can we factor out the "error" to get a working baseline, even if the measurement isn't really heart rate at rest? I doubt it, frankly. No one is controlling for these conditions. The easiest thing you can do is to wait a few minutes for the patient to relax after entering the examination room to get a reading at rest.

gklitz 2y ago

> Is the blood pressure really being measured "correctly" in all those studies? Or not? This is why you do readings three different times a day for several days. And why there’s instructions on how long to dust still before the readings, why you do three repeats with multiple minutes of wait in between, and finally why the averages of those readings aren’t just simple averages. But yes you always have to wonder about every study using self reported home readings if they follow the instructions or not, because it is tedious to do it correctly.

moffkalast 2y ago
The reading process itself is a constant that you can't filter out by doing it repeatedly. Something squeezing your arm with what feels like the force of a hydraulic press surely doesn't have any weird side effects. Anecdata, but I always get high anxiety from not being sure if the thing is actually still working properly or if it's just gonna keep pumping itself up until it explodes in my face or something. Not exactly rational but these sort of things never are. Looney toons ass machine.
- giantg2 2y ago
  "Something squeezing your arm with what feels like the force of a hydraulic press" It shouldn't feel that crushing. I know it's common, but it shouldn't be. It's lazy/rushed healthcare professionals who only want to take it one time suing an automated machine and crank it to 200mm. If you actually put it at 140mm or take it with a manual sphig, it would read a "normal" person just fine without the crushing. The problem is, the people who are high around 130-140 need the machine at least 20mm higher and would need a retake, which means more time.
  - SilasX 2y ago
    I have an automatic at-home blood pressure device, and it does the same thing. Not 200 mmHg, but high enough that I’d freak out if I didn’t know it was normal and would let up soon enough[1]. Did the product designers do that intentionally while still meeting a spec of “not panicking the user in a way that would elevate blood pressure” and getting approved for sale to non-professionals? It seems like this is genuinely hard to work around in practice. [1] I recall it being a staple of 80/90s tv, at least Beavis and Butthead, to have a character use an auto blood pressure device and freak out at being so clamped.
    - HPsquared 2y ago
      There might be a repeatability thing. Always give the full pressure then at least it's one less variable to account for.
      - epcoa 2y ago
        Nah. Modern automatic cuffs are adaptive. They tend to first run up pretty low (like 150), see if there is signal. If not then they have to inflate more and more. They tend to determine where to start next time based on the last reading, so if it had the go up to 200 for the last reading it’ll start there next time. If the cuff is a vise, excluding operator error the most likely cause is actually having high blood pressure.
hirvi74 2y ago
> This is why you do readings three different times a day for several days. What good is this if my monitor is not as accurate as the one at a doctor's office? It's not like my doctor would take my monitor's readings over his.
- devilbunny 2y ago
  You might be surprised. "White coat hypertension" is well-known. Someone with a reliable set of readings from home would be more convincing than someone who says "I get it read at Walmart/CVS once a month and it's ok". Your doctor's office's monitor isn't incredibly accurate. If you want accurate, you need a mercury sphygmomanometer to measure the pressure. Unless fundamental properties of the universe have changed, it will also be comparable to any other readings taken with mercury.
  - bigmattystyles 2y ago
    And it has to be in retrograde.
    - devilbunny 2y ago
      That's a complicating factor, but one that we can usually calculate.
- coatmatter 2y ago
  Find one that is accurate enough and crosscheck it with the one at the doctor by taking regular measurements so you get an idea of trends rather than absolute values. Doctors do know about white coat hypertension - it's not a myth. There's no reason you can't do your own experiments with consumer-level blood pressure monitors from reputable manufacturers. In fact, it was my mother's primary care provider who recommended she buy one for home use. This is what I did with a US$10 pulse oximeter (a Contec CMS50M from China) when my dad ended up in ICU last year, and it was pretty much bang-on with its readings. I've also tested my pulse oximeter on plane trips and know it will drop below 90% when the air is thin (and rise up again if I do some deep breathing), and therefore know it isn't always stuck at a high value. Search PubMed for "The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by the Food and Drug Administration: The Possible Global Public Health Implications".
kbelder 2y ago
I would trust the self-reported home readings more than those taken by professionals, because they're probably happening more often and under less stressful and exceptional circumstances.

hombre_fatal 2y ago

As long as blood pressure variance is randomized then you’re getting a signal, and that happens when everyone is measured in a similar way (or randomized to different ways). You don’t need perfect precision. What you don’t want is to make everyone who, say, smokes wear the cuff while standing up while everyone else gets cuffed lying down.

crazygringo 2y ago
> and that happens when everyone is measured in a similar way (or randomized to different ways) But that's exactly the issue -- that the similarity or randomness is one way for one study, and another way for another study, because of culturally different sets of nurses and/or patients. In other words, you're right it's not affecting results within a study, but it makes comparison between studies questionable. And it makes it equally questionable whether a study's results apply to you, if your signal is 10 units off of a study's signal, and occurs across a cutoff that determines whether you should take a medication or not.

Mathnerd314 2y ago

I guess it depends on the study. If it is just comparing between groups, the conclusions probably still hold if they consistently measured blood pressure in the "incorrect" way. If it is something like "85% of Americans have high blood pressure", then probably the conclusions are incorrect because they are comparing the "correct" baseline against an incorrect measurement method. There are also other ways to measure blood pressure, like recent smartwatches - so read the methods section carefully, I guess.

hluska 2y ago

When my heart went to hell, I bought a blood pressure monitor. Before I left the hospital, I had to agree to religiously test my blood pressure three times a day at the exact same time. Anything beyond that was a bonus, but to provide useful data I needed those three readings a day. As my cardiologist explained, 39 year olds don’t randomly end up spending a week in a cardiac ward so he needed better data to form a holistic treatment plan.

ajuc 2y ago

My wife had a Cryo Chamber Therapy for a few weeks and had to measure pressure and pulse before each session so they let her in. After about a week she was refused entry because her pressure was too high (when she measured it at home - it was normal). Since then she had problems getting admited every time, and she started to fear the measurement (she had to drive there during work and do overtime later). She started arguing with the guy and wasted like 5 days driving there and back during work without having another session because the pressure and pulse were too high (despite both being OK at home). Eventually she went to another person in that hospital to measure her pressure. It was perfect. But when the guy near the entrance to the cryo chamber measured it - it was too high to let her enter. They tried different instruments and the difference was the same. When the guy measured it - it was too high. When somebody else measured it - it was fine. Finally they let her do the cryo chamber without the guy permission :) We assumed the difference was just that she was anxious and frustrated when she's seen the guy, but now I wonder if the difference was the position in which he measured the pressure.

zifpanachr23 2y ago
Had the exact same thing happen when I was doing a Ketamine therapy thing a while back, and I definitely think the anxiousness about the reading had something to do with it. I've always had perfectly okay blood pressure whenever I have it done at a regular doctor's appointment, so I think knowing that the reading actually matters definitely increases my blood pressure. Ended up getting a doctor's note saying "they don't actually have high blood pressure they are just reacting normally to possibly having to be sent home and reschedule" more or less.
- joncrocks 2y ago
  I think this is a well-known thing, being apprehensive about having the measurement being taken can influence the result - https://en.wikipedia.org/wiki/White_coat_hypertension https://en.wikipedia.org/wiki/White_coat_hypertension
running101 2y ago
I get anxious when taking blood pressure as well. There are techniques your wife can try before entering the cryo-chamber look up the 478 breathing technique. I developed a white coat blood pressure readings over the last several years measuring a stage one or stage two hypertension at my last doctor visit. I use the 478 breathing technique and my blood pressure readings are normal at my last dr visit.

lysace 2y ago

I found that that the measured BP was consistently significantly lower if I didn't look at the device's display while it was doing it's thing. This at home, with a quality device, after doing it many many times.

kyleee 2y ago
Yes, i experiment with eyes open/closed as well

lottin 2y ago

Exactly, this is my concern as well. They say you have to be seated for 5 minutes at least, completely relaxed, not hungry, not having to go the bathroom, in a quiet a room, it must not be too hot or too cold, with both your feet on the ground, before you can have your blood pressure measured, otherwise the reading could be 'artificially' high. Really? It seems to me that if you do all these preparations, the reading will be artificially low, since such conditions are nothing like the conditions that you'll typically find yourself in through the day in your everyday life.

BaculumMeumEst 2y ago
The goal is to get a clinically relevant measurement, captured at rest under specific conditions, not a measurement that's representative of a random moment during everyday life.
- saalweachter 2y ago
  We're also treating people for things like blood pressure somewhat statistically rather than individually. The studies say, people who have a blood pressure measured this way, that is above X, have an N% higher chance of dying M years sooner of A, B or C than people who measure under Y. If you treat with medication Q it lowers blood pressure, measured this way, by Z points, increasing lifespan by W QALY. Are you treating people who don't need to be treated and missing people who do? Could you achieve better results with continuous, invasive blood pressure measurements while the patients engage in every day life? Probably, but then you're increasing the cost of both the study and the public health intervention exponentially for gains in the margin.
- lottin 2y ago
  But if the measurement isn't representative of your actual blood pressure what's the point of taking it? It's completely non-informative. Another problem is that even under very controlled conditions, I sometimes find big differences in blood pressure from one minute to the next.

makeitdouble 2y ago

Reading around (e.g. [0]) it sounds like variance isn't something researchers care for, probably with the assumption that screening with a higher value is better than missing an issue from a lower value. We see the same for body temperature (speed and convenience is usually prioritized over accuracy) and weight (2% variation is largely accepted). Afterall guidelines are already off as by definition, as they don't account for individual circumstances, so perhaps aiming for accuracy is useless in most settings. [0] https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/diagnosis-treatment/drc-20373417 https://www.mayoclinic.org/diseases-conditions/high-blood-pr...

SV_BubbleTime 2y ago

My doctor was handing me, hypertension, pamphlets, and talking about medication. Finally realized, that I was habitually late, getting to my appointments and always taking the stairs. Don’t do that.

scottmf 2y ago
iOS voice dictation?
- SV_BubbleTime 2y ago
  Yea. But it’s mostly good except for the commas
  - scottmf 2y ago
    Haha, no I agree, but it was immediately, recognizable :)
- mh- 2y ago
  With pauses to keep his BP low.

arcticbull 2y ago

Also doctors and nurses are known to do an abject awful job of measuring bp according to the defined procedure. It’s usually way off when taken clinically. Ars article here but there’s plenty in pubmed too. https://arstechnica.com/health/2024/10/your-doctors-office-could-be-reading-your-blood-pressure-all-wrong/ https://arstechnica.com/health/2024/10/your-doctors-office-c... [edit] The prep guidance is… > You must not eat, drink, exercise, or smoke within 30 minutes of a reading. You must have an empty bladder. You must sit straight up in a chair with back support. Your legs must be uncrossed and your feet must be flat on the ground. The arm to be measured must be rested on a flat surface so that it is at the same level as your heart, not lower, not higher. You must sit calmly, without talking for five minutes to relax before the reading. When it's time, an appropriately sized cuff should be wrapped around your bare upper arm, right above the elbow; it should never be wrapped over clothing. At least two readings should be taken, with the average recorded. Ideally, readings should be taken in both arms, with the highest readings recorded. When was the last time you got it measured properly? Literally never for me in a clinical setting. I don’t know why they bother honestly.

ericmcer 2y ago
Probably never, I have really long arms and they usually take it just barely above the elbow also. I have always been on the higher end even when in my 20s and training/dieting for athletic events. Used to flummox me until I bought my own meter, they can be like $30.
ttymck 2y ago
And what's the typical variance (from "actual") for a "usual" reading?
- arcticbull 2y ago
  Good question, for myself personally (anecdotally) I got systolic of 145-ish in the doctor's office and 120-ish at home. This was validated by a medical take-home 24h cuff.
- matheusmoreira 2y ago

mgh2 2y ago

This is why it is better to take three measurements and do an average every time to minimize errors. The studies on correlation probably have a large enough sample size to become statistically significant - i.e. you have to read the "Method" section to find out how reliable it is, this requires certain kind of statistics and/or scientific background.

buu700 2y ago

Another fun factor I learned about five years ago is temperature. My gym was offering a complimentary fitness evaluation, which among other things included a blood pressure test. The trainer was horrified to see 140-something over something equally terrible, and started explaining how she'd have to refer me to a doctor and advise that I refrain from strenuous physical activity, until I showed her a report from my annual physical a few days prior with 106/70. Turns out that walking to the gym in shorts and a T-shirt in late January causes enough vasoconstriction to really screw with some measurements.

coatmatter 2y ago
I once had a similar high outlier blood pressure reading after a somewhat busy day followed by running through the city to my blood donation appointment. Who knew that BP is affected by external factors and doesn't stay constant throughout the day‽‽
- matheusmoreira 2y ago
  Having a full bladder will raise your blood pressure.
  - ghastmaster 2y ago
    It raises my heartrate as well. I know my bladder is full many times due to the heartrate rather than feeling my bladder. I'm not sure if others notice this. I assumed without looking at the anatomy that the arteries to the lower extremities are under pressure from the bladder.
- gcanyon 2y ago
  I had a similar trip to the blood bank once: I rode my motorcycle from Palm Springs to San Diego, straight to the blood bank, on a cold January morning. As usual, they took my temperature. It was 95-something. They said, "Are you feeling alright?" I said, "Sure, I should have worn better clothing for the ride down here, but I'm fine." They conferred, then took my cold blood :-)
- 2y ago

Zenzero 2y ago

> are the studies always really done with far more accurate blood pressure readings, where the patient sits still for 5 min beforehand, keeps their legs uncrossed, is totally free of stress and anxiety, didn't exercise beforehand, etc.? In situations where blood pressure really matters, we aren't playing around with the cuff and hand positioning. The patient gets an art line.

lazide 2y ago
Oddly, at least a decade ago, at least one Bay Area hospital stroke protocol required manual BP readings with a sphygmomanometer. And the patient had an art line. Not sure if they didn’t have the equipment for art blood pressure or what, but good BP readings were important. And they had all the fancy equipment. Patient presented with an ischemic stroke, and was getting a stent + thinners, so anything problematic was likely due to something immediately life threatening. They didn’t want an automatic cuff system because it could cause something to burst with the pressure ramp up. At least that is what the surgeon said. Source: I was the EMT-B on his clinicals who stayed with the patient in the OR while he got stented and took readings every 5 minutes because none of the nurses were ‘current’ on the manual cuff. or so they said. I was pretty fresh, and was pretty good at it at the time, but I think they were just making excuses now haha. I held his hand through the procedure to help calm him down too, which seemed to help a lot. Patient 20 something that day. Emergency Rooms are quite an experience. I volunteered for Halloween Night, which added to it I’m sure. PS. Watching the Dr install the arterial catheter (or maybe it was a port?) in the ER was wild. Literal stream-of-blood-shooting-across-the-room-and-spraying-on-the-wall wild. Never seen anything like it before or since. I was glad I had my safety glasses on.

haldujai 2y ago

> Is the blood pressure really being measured "correctly" in all those studies? Or not? Probably incorrect in most studies, especially large population ones that influence treatment guidelines. It’s academic and doesn’t practically matter though. The pathogenesis of hypertension related disorders (kidney failure, heart failure, stroke etc) is well known. It’s not in doubt that sustained hypertension is bad, that there is increased risk with higher blood pressure and that patients with high blood pressure undergoing treatment suffer less of these bad outcomes.

wonnage 2y ago

Kaiser measures BP on every visit and arm position seems like the least of their worries: - no rest period before measurement - measured through a medium-thickness sweatshirt sleeve - cold hospital hallway - no back on the chair - no height adjustment on the chair - no real surface to rest your arm on (They usually use the handle of the equipment cart that the BP monitor is mounted to) - Zero attention to cuff positioning/orientation I've come in at 160/90 but went down to 120/80 after rotating the cuff 1-2cm and resting for a few minutes. Manual measurements from the doctor are usually more accurate.

EPWN3D 2y ago

Kind of wonder the same thing about BMI and water composition. Your body weight can vary by up to 10 pounds depending on how much water you're retaining. I've never been able to find information about the composition assumed or measured when coming up with BMI numbers. Granted I don't think the ultimate effect is huge, and you can eliminate it by weighing yourself daily and taking an average. But most people don't do that, and a spot-check at a doctor's office certainly can't do that.

matheusmoreira 2y ago
> I've never been able to find information about the composition assumed or measured when coming up with BMI numbers. BMI is just weight divided by height squared. No distinction is made between type of mass. Muscle mass, fat, bone, water? BMI couldn't care less. It sums all that stuff up into a single value. Think of it as a number that roughly correlates to disease. There will always be false positives and false negatives. False positives are acceptable. We want to minimize the number of false negatives. There are nearly ten billion humans on Earth. It is not possible to fully evaluate every single one of them. Gotta run a SELECT statement. Filter them based on some criteria, and fully evaluate those that match. BMI isn't perfect, but it takes less than one minute to measure the variables and compute it. The equipment required is cheap and easy to use. Speed, efficiency, cheapness and ease are extremely important factors when you're applying this at national scales. Patient might turn out to be a physically fit 100 kg 1.7 m 34.6 kg/m2 body builder. That's alright. Our objective is to make sure the obese and the malnourished can't escape the sieve.
- blitzar 2y ago
  You could probably get to a better generalisable number by slapping waist circumfrence in there as well.
  - matheusmoreira 2y ago
    Absolutely. Waist circumference should be and is considered as well, especially when evaluating obesity and its comorbities. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027970/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027970/ The combination of BMI and waist circumference is even better.

andreareina 2y ago

My understanding from people who follow the literature is that the studies are done with the recommended procedure, 5 minute wait and all.

lo_zamoyski 2y ago

Yes, I was thinking the same. If everyone is measuring heart rate under similar conditions, and then correlating that heart rate with other factors, is that perhaps alright? Can we factor out the "error" to get a working baseline, even if the measurement isn't really heart rate at rest? I doubt it, frankly. No one is controlling for these conditions. The easiest thing you can do is to wait a few minutes for the patient to relax after entering the examination room to get a reading at rest.