Commonly used arm positions can overestimate blood pressure readings: study

https://medicalxpress.com/news/2024-10-commonly-arm-positions-substantially-overestimate.html

by wglb • 2 years ago

331 230 2 years ago

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.?

gklitz3• 2 years 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• 2 years 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.

hirvi74• 2 years 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.

kbelder• 2 years 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.

Mathnerd314• 2 years 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.

hombre_fatal• 2 years 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.

crazygringo3• 2 years 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.

hluska2• 2 years 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.

ajuc2• 2 years 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• 2 years 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.

running1013• 2 years 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• 2 years 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.

kyleee4• 2 years ago

Yes, i experiment with eyes open/closed as well

lottin2• 2 years 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• 2 years 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.

makeitdouble• 2 years 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-pr...

SV_BubbleTime2• 2 years 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.

scottmf2• 2 years ago

iOS voice dictation?

arcticbull3• 2 years 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-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• 2 years 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• 2 years ago

And what's the typical variance (from "actual") for a "usual" reading?

Zenzero6• 2 years ago

Doctors recognize that non-invasive BP measurement is an imperfect screening tool. Anybody worth their salt isn't getting worked up about these level of details, because it's largely a waste of time and effort. The solution to an error prone screening tool is not to repeatedly use the screening tool. You move on to more accurate and focused methods of testing.

from-nibly2• 2 years ago

What's the point of taking your blood pressure if doing any of these things causes significant variance? I'm not meditating at home or out and about all day. So why does it matter what my blood pressure is in one single state? What if I'm in an elevated state all the time? What if I never am? It makes it really hard to believe that blood pressure readings are anything more than nonsense.

mgh2• 2 years 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• 2 years 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.

coatmatter2• 2 years 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‽‽

JTbane• 2 years ago

Any exercise will raise your BP by quite a bit.

Cthulhu_2• 2 years ago

No medical advice should be given on the basis of a single blood pressure test.

I've donated blood about a dozen times, my BP has been high on one or two occasions but only if it was a pattern after two or three times did they flag it up, and since it went back down the next time it was no longer a problem.

They did send me letters about the amount of ferritine in the blood though; the first time it was too high (probably due to having a thing for food that turned out to be high in iron for a while around that time) and they advised I see a doctor for it, but it went down on its own after that. And the last time it was too low, but that's a normal thing if you donate blood a few times (it was every two months for a while), they basically don't summon you again for six months.

TL;DR, a single measurement says nothing.

Zenzero6• 2 years 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.

lazide2• 2 years 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• 2 years 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• 2 years 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• 2 years 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.

matheusmoreira6• 2 years 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.

andreareina• 2 years 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_zamoyski2• 2 years 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.

swores3• 2 years ago

I've never looked into research on this subject, but I always assumed this was already well established and known - and it was definitely somewhat already either known or at least believed to be the case:

- Every doctor in the UK I've ever seen do a BP test has made sure the patient's arm is in the right position, rested on a table/cushion if needed, in a way that matches the findings in this study (and while I've only needed my own BP tested once or twice, I've sat in on many, many doctors while they tested the BP of family members of mine).

- My home BP device is a Braun wrist cuff (and is at least a few years old), which has a built in feature that uses an accelerometer to guide you to raise your arm until it's at an angle which means your wrist is at the same level as your heart (this one: https://www.cora.health/guide/best-blood-pressure-monitor/#1... )

tocs3• 2 years ago

Can you trick the Braun device into thinking your wrist is level with you heart?

swores3• 2 years ago

Yes - it's just a digital spirit level of sorts, that instead of being calibrated to align with the ground is calibrated such that, based on typical angles and dimensions of a human body leads to the wearer holding their arm up in front of them with the device in line with the heart.

Here's what it looks like, the device won't start until you've got the ball to hover in the middle circle, but it has no way of knowing if you're doing it properly or if you're lying down or leaning your body forwards or whatever else would mean that the angles no longer put it level with your heart.

https://imgur.com/a/pV6xcpc

edit to add: so when used correctly it looks roughly like this - https://m.media-amazon.com/images/S/aplus-media/vc/573a171a-...

Basically the same logic as, for traditional upper arm cuff devices, giving the instruction to rest your arm on something next to you that allows your forearm to be resting both comfortably and straight, parallel to the floor - which again, doesn't technically mean the middle of your upper arm must be level with your heart, but since nobody would really be comfortable putting their forearm flat on a low down coffee table or a high up standing desk it works as a proxy that's simpler than asking people to think about lining anything up with their internal organs.

corry2• 2 years ago

I've used the Braun wrist cuff, and while the heart-level feature is cool and perhaps good enough to mitigate position issues, I found that it was very unreliable vs. cuff measurements.

What do I mean by "unreliable"? Two things - (1) internally consistency for the given device and (2) not closely correlated to the arm cuff measurements.

My method: I would wear both devices and take a series of readings (like 5+ from each in a session, and did multiple sessions a day).

My results: while the cuff readings of course had some minor variation in of themselves, they were largely consistent with themselves (i.e. clustered around the average for the session) whereas the properly-positioned (according to the heart height feature) wrist measurements were all over the place showing big swings between readings and a wider dispersion from the mean.

Then there was the issue of did the wrist average measurements roughly correlate to the cuff averages - and not only was the answer "no", it would vary whether it was higher or lower. Which is a shame - it's ok if it was, say, overstating things by +5 mmHg but overstating at that rate consistently (because then you could mentally adjust the outputs); but when it's inconsistent you're just left scratching your head.

As I wrote about in another thread, the continuous wrist monitor Aktiia that I've been trying gets correlated explicitly to an arm cuff and seems far, far more accurate and consistent than this Braun device. It uses optical imaging of your wrist's blood vessels vs. physical pressure on a cuff.

All this to say - test for yourselves! Try multiple arm cuffs, even. While the exact numbers are less important than the trend, you need a device that you can trust w.r.t. output.

swores3• 2 years ago

It's possible you were unlucky and had a dodgy device (or it's possible luck has misled me to believing mine is better than it is).

I chose it because my GP recommended that in his experience it was accurate, and in addition to testing it against two brands of normal upper-arm cuff (consumer) devices that a friend and a relative had, I also took it when taking my dad to his GP who the previous time had expressed interest in the wrist-based device I'd mentioned using on my dad, and she tested it against her two devices (one an electric upper arm cuff, the other an old-school manual upper arm cuff that involves squeezing a rubber thing on the end of the hose to inflate it and a manual clock-style dial for readings).

We didn't detect any unreliability in it compared to any of those 4 devices (two consumer, two NHS-approved & doctor-owned) - all 5 seemed equally reliable (based on our not exactly lab-quality testing, but still we weren't lazy enough to do single readings or anything like that).

tired-turtle• 2 years ago

Blood pressure measurements at the doctor are the bane of my (medical) existence. Mix minor white coat syndrome with time blindness and you suddenly have high blood pressure because you barreled up the stairs to the second floor office moments before the nurse took a reading.

My doctor was initially befuddled because by all other metrics I am in good health, but it’s amazing how you can go from 90/55 at home to 140/75 at the office. We do the measurement at the end of the appointment now to varying success.

bluGill• 2 years ago

Weird, I ride my bike to the doctor, my heart rate is often elevated from the ride and my blood pressure is still normal (barely above low - though I've had enough different tests over the years to believe that exercise is having nearly zero effect)

atahanacar11• 2 years ago

Literally the first year of medical school, we were taught to let the patient rest for at least 5 minutes before taking vitals, while also asking about recent exercises or caffeine intake. This reduces the likelihood of a mistake, but white coat hypertension is still a thing. That's why we also teach them/relatives how to correctly measure BP on their own and ask them to measure it at home, preferably after waking up before eating anything.

ajuc2• 2 years ago

My wife has one specific guy doing the measurement that she hates and when he measures her pressure it's like 10-20 higher.

It's also the guy that measures pressure before letting people enter to the cryo chamber, so she spend about a week rescheduling and arguing with him to let her in.

When she went to another person at the hospital her pressure was perfectly fine, and switching the instruments didn't helped - if THE guy measured it - it was too high - when it was somebody else - it was OK, no matter the instrument used :)

standardUser• 2 years ago

No doctor or assistant bothered to tell me about the impact of caffeine. I had a few borderline-high readings over a few months and was concerned until I realized I was drinking my normal 2-3 cups of highly caffeinated coffee just before these visits.

eagerpace• 2 years ago

I am not a doctor and this is not advice. This is a standard medical test I have completely given up on any doctor to perform accurately. I do it myself at home once or twice a month. I do it with the same device, in the same chair, at the same desk, the same time of day, after I’ve ate and drank the same thing. Yes, I still let everyone take it because it’s typically a precondition of receiving care but my readings at home are completely different and give me a more accurate data point that actually makes me feel good about the progress I’ve been making on my health.

I’m actively looking for more healthcare I can do this way. I trust my data and it all coming together on the safety of my personal device. We don’t need doctors with extremely limited datasets to do this and try to find obscure correlations for us.

AStonesThrow5• 2 years ago

typically a precondition of receiving care

I've achieved exciting results by flatly refusing vitals checks at each and every medical appointment. Especially psychiatrists. The PCPs always gamely admire my self-reported histories and graphs, commenting how nicely the trend line goes down, and then completely dismiss the results in their clinical notes.

However, I did lock horns with a particular chiropractor. I filled out the "pre-existing conditions" form with candor and honesty. I permitted a BP check. (His method was 100% manual sphygmomanometer.)

Then he informed me that he wouldn't touch me until my BP was controlled and normal. Yes, a chiropractor, not a cardiac surgeon. Geez.

In the past, I've tried to avoid submitting to blood draws and labs, because those are 100% fishing expeditions, and not actually attempting to diagnose a complaint or symptoms. (They love to misdiagnose hypothyroid or diabetes so they can begin destroying your endocrines.)

Unfortunately, clinics do these orders on a schedule, so if you avoid labs for a while, the orders simply pile up until they contrive to get them all done. I couldn't win. Still putting off colonoscopy: 2.5 years late, and counting!

rscho10• 2 years ago

But why go to these practitioners if you don't trust them ? Nobody should be forcing you. Is it because you want access to treatment solely on your own terms ?

atahanacar11• 2 years ago

Still putting off colonoscopy

I hope you won't regret putting it off.

They love to misdiagnose hypothyroid or diabetes so they can begin destroying your endocrines

Yes, my favorite pastime when I'm bored of treating "actual" diseases.

I fail to understand how a well-educated group of people (aka. HN) can be this against the scientific method.

Spooky23• 2 years ago

Lol.

Hopefully you get lucky. Why address cancer, insulin resistance or stroke risks early?

flextheruler• 2 years ago

Amazing it’s like you’ve figured out the optimal strategy of still spending the same amount of time going to the doctors but getting as few benefits as possible.

I’m pretty sure you can decline care and get second opinions no matter what.

I don’t know your family background, but I have quite a few older male relatives who died from cancers that if caught early have high survivability. They were all suspicious of the profit incentives of the medical system and felt they knew better or were tough enough to not care. My grandfather had a heart murmur, so he used that as an excuse to never go to the doctors. “They just want my money I already know my heart will kill me soon so why bother”. He died of colon cancer. I’m sure they all regretted it.

Zenzero6• 2 years ago

They love to misdiagnose hypothyroid or diabetes so they can begin destroying your endocrines

Im sorry but as a doctor this made me crack up. I don't know what it is about HN that makes people jump into every medical thread and say really absurd things. Skipping screening tests isn't one-upping your PCP. You just get to play harder with specialty when stuff starts to break. Good luck buddy.

kaycebasques• 2 years ago

after I’ve ate and drank the same thing

My doctor recommended doing it first thing in the morning, before eating or drinking anything. That's probably an easier way for the general population to establish a consistent baseline

atahanacar11• 2 years ago

It's not only easier, but the actual correct way of doing it. That's why your doctor recommended it.

atahanacar11• 2 years ago

This is a standard medical test I have completely given up on any doctor to perform accurately. I do it myself at home once or twice a month. I do it with the same device, in the same chair, at the same desk, the same time of day, after I’ve ate and drank the same thing.

You are assuming the average patient is this careful about measuring their BP, or anything about their health. You are also assuming the average patient measures their BP correctly, which is obviously untrue as evidenced by some other comments on this post. You are also assuming patients always tell the truth about their own measurements.

We don’t need doctors with extremely limited datasets to do this and try to find obscure correlations for us.

I don't understand what you mean by this. None of us finds obscure correlations with limited datasets. We don't diagnose someone over a single BP measurement.

rootusrootus5• 2 years ago

We don't diagnose someone over a single BP measurement.

Yeah I feel like no doctor of mine has ever been the type to do that. My current PCP wouldn't prescribe meds for hypertension until after I took my own BP at home for a month (it was not catastrophically high when measured at his office, he might have taken a different approach in that situation).

Spivak2• 2 years ago

Honestly I'm not sure what a single point-in-time reading even accomplishes. I've been hooked up to a continuous blood pressure monitor a few times and it's always fun to see how low I can get it. It seems pretty useless without seeing where it fluctuates over time not in a doctor's office.

iwaztomack2• 2 years ago

How do these work? You can't stay compressed all the time? Is it intravenal?

Spivak2• 2 years ago

The ones I've been hooked up to just compress every few minutes so not terribly fancy.

aidenn0• 2 years ago

Once, when hospitalized, I had an arterial BP monitor that was continuous. The last systolic number I remember seeing before passing out from sepsis was in the 70s.

laz• 2 years ago

Aktiia makes a continuous optical blood pressure monitor that is available in the EU. It's like wearing a fitbit, but for bp. You calibrate it with a pressure cuff once a month.

I'm pretty sure they're going through fda approval in the USA now.

WarOnPrivacy• 2 years ago

Automated BP cuffs painfully over-inflate; my BP is 20+/15+ higher when they're used.

I ask nurses to take my BP manually.

SirMaster• 2 years ago

Hmm, I find that the tighter the cuff goes, the lower my reading goes...

elric2• 2 years ago

I had a similar issue, which was remedied by getting a larger cuff. In retrospect it makes sense that one size does not fit all, and apparently my biceps are on the larger side.

rscho10• 2 years ago

Cuff sizes are targeted to a range of arm sizes. The range should be stated either on the cuff or in the manual. Using improper sizes over/underestimates the pressure values.

BenFranklin1002• 2 years ago

I’ve never seen a discussion how ‘reactive’ one is physiologically either when discussing BP. That is, is one the kind of person who is generally calm throughout the day, or is one who has larger swings based on various stimuli? I’ve had readings as high as 155/95 when stressed rushing to a doctor’s office visit and readings as low as 105/62 when calmer. I suspect blood pressures varies wildly through the day, and this variation depends on a person’s physiology.

hluska2• 2 years ago

I had a major heart scare when I was 39 so I’m quite obsessed with my blood pressure. This is anecdata based off of my own experience with my heart, brain and body.

(Note that this is based off of someone capable of developing a heart problem in his late thirties so hopefully none of this will apply.)

Before I started running for fun, running up to a doctor’s office would absolutely spike my blood pressure. That was a combination of anxiety (which is/was an issue), cardiovascular health and basic physical reactions to exertion. Since I started running for fun, that relationship has completely changed. I don’t get the anxiety based blood pressure changes because I find running really fun and rewarding.

When I lift weights, my blood pressure will read a little higher for at least 24 hours after. The heavier I lift, the more my blood pressure will lift. I see a similar relationship with volume, but it’s not as linear as weight. So if I have to do fifty total reps to failure my blood pressure will be higher, but not as high as if I had done ten total reps to failure.

Food and alcohol have tremendous impacts. Cannabis has an impact but nowhere near the impact of either food or alcohol. Armed only with blood pressure data, I could make a good case for fast food and beer to be illegal. My case wouldn’t be as strong for cannabis. Caffeine is really fucking weird - it increases blood pressure up to the point of addiction. Then, not feeding the addiction will spike my blood pressure even more.

And I haven’t even begun to talk about how heavily my brain is involved. I dealt with undiagnosed ADHD through developing some very obsessive habits. As a consequence, I can quite literally obsess my way back to blood pressure medication.

Judging by how much personal data I have on my blood pressure, I’m sure you’re very surprised that I tend to be obsessive. :)

So anecdotally, you are 100% correct. But I can add some more anecdotes to hopefully ease your mind. When I got out of the hospital, I had to promise my cardiologist three perfect readings a day; meaning that I would religiously check my blood pressure at the same three times each day. Needless to say, I checked it way more than that. But there is an awareness that different levels of need require different levels of scrutiny.

The only part I still wonder is if my cardiologist knew that giving an obsessive person metrics would lead me into running. This may have just been a way to get me back into shape.

atahanacar11• 2 years ago

I’ve never seen a discussion how ‘reactive’ one is physiologically

Then you have never looked for it. This is pretty basic stuff taught in the very first year of the medical school.

when stressed rushing to a doctor’s office visit

Even has a name: white coat hypertension.

I suspect blood pressures varies wildly through the day, and this variation depends on a person’s physiology.

Yes it absolutely does. Just like your heart rate varies throughout the day, your BP keeps changing as well. That's why we like to measure it over 24 hours before any diagnosis.

BenFranklin1002• 2 years ago

Well then, instead of being smug, how about providing a reference? Specifically, can you link to information about the distribution of individual blood pressure daily variances across a population? This is different from white coat hypertension,something which nearly all of us are familiar.

To get you going here is a 2009 article on labile hypertension. It discuss the topic but does not provide any quantitative information on population distribution.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8673041/

Edit: here’s a link to a more recent reference:

https://www.imperial.ac.uk/news/251055/blood-pressure-variab...

Apparently, contrary to your assertion that an individual’s blood pressure variability is part of established 1st years med student’s knowledge, labile hypertension seems to be an active area of research.

iwaztomack2• 2 years ago

4~7 mmHg isn't going to make or break a hypertension diagnoses. 20~30 mmHg definitely.

aksss2• 2 years ago

This shouldn't be downvoted.

If you're +-7 in your reading, don't panic yet. If you're there with a stage 1 or 2 hypertension diagnosis (130-140+ systolic), the margin of error discussed in this article isn't necessarily meaningless, but remarkably close to it - you need to address an issue there.

More as a PSA for you hardworking programmers and IT managers out there: if you have chronic hypertension, address it sooner than later. If you think to yourself that you'll start jogging daily starting next week, and your doctor is giving you the option for meds, just get on the damn meds. If you start an exercise regimen that can quantifiably manage it without the meds later, great. Don't let the perfect be the enemy of the good. Hypertension is the silent killer, and before it kills it contributes to all sorts of other bad problems and conditions.

kayodelycaon• 2 years ago

Hypertension can also make you feel like crap. It made my chest feel tight, which did not help my anxiety.

aranchelk• 2 years ago

As a just-in-time bordering on chronically late individual (typical engineer), sprinting on foot or bicycle to the doctor’s office has led to some unusually high reading.

kyleee4• 2 years ago

I always wonder to what extent coffee affects the readings as well (on top of rushing into the office, commonly up stairs).

btilly2• 2 years ago

I've never seen a nurse not insist on the right position.

However I've always wondered how much of a difference my long torso makes when my blood pressure is measured. I'm 6'3", and it's mostly torso. The result is that a table that is the right height for most people, is low for me. And adjusting the table to match my body is something that I've seen a lot of variation on.

reneherse2• 2 years ago

Seems it would be easy to equip exam rooms with a set of basic foam blocks that could help with patient positioning for this and other routine procedures.

Can any medical professionals chime in on how it's usually done for tall folks?

"Long torso body type" is, in general, an under-appreciated factor in ergonomics and product design, IMO.

A couple of off-the-cuff examples:

-The longer your torso, the worse a laptop computer affects your neck and posture. For long folks, upright posture requires keyboard and monitor to be vertically separated even more than most off-the-shelf monitor/desk/keyboard trays will allow. So a monitor hinged directly to a keyboard is the worst of all possible configurations.

-Most recent automotive seats seem to force the head forward, excessively curving the spine, and the longer the torso the worse the effect.

On the opposite side of the bell curve, a safe driving position is hard to achieve for drivers around 5ft tall and under. Correct/safe distance from airbags and pedals seems to be overlooked for those of shorter stature.

I wish solving problems experienced by body proportion outliers was a higher priority for product companies.

rootusrootus5• 2 years ago

Add clothes to that list. It's such a pain in the butt to find shirts made for people who are long torso without ending up with a shirt that's larger in every other dimension too. Even ones specifically labeled 'tall'

kyleee4• 2 years ago

Why are recent auto head rests doing this? I hate it and I am nearly to the point of removing the head rest when I drive (but maybe that has downsides in an accident scenario).

btilly2• 2 years ago

That isn't just recent automotive seats. I've been having that problem for decades. Particularly bad offenders are Budget rental trucks and airline seats.

But it is getting worse. The more ergonomic they try to make the seat, the worse it is to sit in. My usual reaction to renting a car is, "Well, there's another model that I'd never consider buying."

mise_en_place• 2 years ago

I was also fed up with inaccurate readings, and was trying to prototype a medical device that would have an adjustable cuff based on arm size. I ran it by my concierge doc, but apparently the latest tech is to use light waves to measure BP, similar to how wearables are doing pulse OX and Heart Rate. The technique is known as Photoplethysmography (PPG).

rscho10• 2 years ago

There are devices that are sold with various swappable cuff sizes.

modeless• 2 years ago

I can lower the results by 10-20 points just by breathing deeply during the reading.

rscho10• 2 years ago

Yes, everyone can do that to some extent.

EasyMark• 2 years ago

Yeep, definitely can drop 10-12 for me as well

floam• 2 years ago

Only time I ever recall a nurse that insisted on doing BP measurements wrong was .. in jail. And not like all the nurses there, just this one person who did not care about anything besides flirting with corrections officers and getting the hell out of there ASAP.

bonoboTP3• 2 years ago

Real-life medical practice is basically going through the motions, then intuitively guessing the issue, prescribing something common since most cases are so banal and next patient please.

Engineer-minded people can discover lots and lots of such "obvious" issues in healthcare and of course the answer isn't that nobody would've guessed it, it just doesn't matter. Healthcare (outside of very specific diagnosable illnesses) is 90%+ medicine theater. People expect some pills, they want a few words with someone in a white coat, and their problem goes away usually by itself. Chronic persistent issues without obvious cause befuddle docs and they often don't find anything even after lots of tests.

Our better health and longevity today is more due to better work conditions, better food, better sanitation and food preservation, basic vaccines, basic disinfectants, basics like penicillin, smoking less etc. And the low hanging fruit to improve further is lifestyle: eating/drinking fewer calories (especially less sugary stuff), exercising/sleeping more and having better social connections. None of it is particularly arcane or in need of precise measurement.

rscho10• 2 years ago

Engineer-minded people can discover lots and lots of such "obvious" issues in healthcare

It is a defining characteristic of "engineer-minded people" to think they understand better than others. Amusingly, they won't pretend to repair their car engine better than a mechanic, but they will strongly believe they understand all the bad tricks and failings of doctors. They almost never understand that current medicine is mostly experience and not hard science. Future medicine is science. 2024 medicine is not, and cannot be.

bonoboTP3• 2 years ago

I wouldn't put the blame on them though. There's a lot of obfuscation and posing as science.

But at the moment it's intractable to do it at scale at a meticulous, evidence-based way. It's a bit of a Santa Claus moment to realize this. People want to believe someone has a proper grip on things. Medicine has done wonders in narrow, specific things like various surgeries - I'm mostly talking about everyday GP stuff where some average 65 year old has generic issues like blood pressure. It doesn't mean that nothing can be done, and I'll in fact say that a smart person with some biology/chemistry background and internet access can often figure out what they actually need,better than a median doctor with limited time and little deep thought effort to spend on the case.

Cultural change is very hard, especially since doctors enjoy a very high status which they earned through long years of very hard work. So the attitude similar to the opposition to Semmelweis persists.

quantadev8• 2 years ago

I'm convinced most people take BP wrong.

Here's how:

Lie down on a bed on your back, and put the cuff on your arm and get the 'button' within reach of your finger to turn it on. Then completely relax (and DO NOT move) with soft music or whatever. Then without moving your body at all, after 10 minutes (at least) push the button to start the pressurization and reading.

This gives an accurate reading and is often DRAMATICALLY lower than if you don't do it this way. I was convinced I had super high potentially life-threatening BP until I learned this.

Now if you want to see I'm right, get up and walk around some and then sit back down and take another reading. It will be noticeably higher, because your heart starts pumping harder even from minimal movement.

geye12345• 2 years ago

I don't disagree, but wouldn't the counterargument be that the 120/80 and 140/90 thresholds (or whatever they've redefined hypertension as) apply precisely to sitting rather than lying, and after only a minute's stillness, rather than ten? And also that you spend 16 hours out of 24 not lying down?

epcoa6• 2 years ago

You don’t live your day to day life listening to soft music, lying down ready to doze. If your BP is elevated due to stress throughout the day it’s elevated, you will accumulate the harms. Idealizing conditions also gives a misleading reading.

Now if you want to see I'm right, get up and walk around some and then sit back down and take another reading.

This doesn’t prove you’re right, just demonstrates normal physiology. Kind of like saying when you dyno an engine you should do it at idle. That is a valid measurement, just not the one that’s interesting.

In a healthy adult you will see a more significant increase in systolic pressure, but mean pressure shouldn’t rise nearly as greatly.

What you’re trying to observe is not the minimum ideal (your method) nor the short term maximums but an average of normal activity.

There’s a reason why ambulatory BP monitoring is the gold standard for diagnosing hypertension.

quantadev8• 2 years ago

If you go to an emergency room and say you've taken your BP and it's high, they'll do basically what I said. Lay you down, let you relax 10 min, and then take a reading. If the reading comes up 120/80 they'll say go home, you're fine, whatever you did to take the BP yourself was wrong. I've seen this happen to someone. That's how I know.

atahanacar11• 2 years ago

This gives an accurate reading and is often DRAMATICALLY lower

Just because it gives lower results doesn't mean it's more accurate. I can raise my arm during measurement or use a tourniquet above the cuff and get a lower result. That doesn't mean the measurement is accurate at all.

There are standardized procedures on how to measure BP. Your "accurate" method is not one of them.

quantadev8• 2 years ago

The word "accurate" was the wrong choice of words. The machine itself is always going to be "accurate" if it's working correctly, and cuff is used right. Perhaps "proper" was a better word, since we're not talking about the accuracy of a measurement.

Since you'll get a higher readout after exercise, or even moderate daily activities, it's recommended that the person be perfectly relaxed for a few minutes before taking the reading. What I described is just my way of being perfectly relaxed, and what I know for a fact doctors do if they suspect an actual BP problem, and want to "scrutinize" it to find the true lowest resting reading.

rootusrootus5• 2 years ago

I've heard that for some people it's exactly the opposite. Standard procedure, IIRC, is to have the arm resting in a position that puts the cuff right about even with your heart. But some people get really big jumps in BP when supine, and I've heard it suggested that doctors might want to start doing their BP tests in that position because those people may not get diagnosed correctly despite spending a third of every day with high blood pressure.

quantadev8• 2 years ago

I think the main point is not necessarily the laying down part, but it's just that you need to be perfectly still for 10 min. Your BP will still be dropping more even after 5 min. This is just how to get the lowest resting reading. Of course others on this thread have balked about whether this lowest readout has value on it's own.

geye12345• 2 years ago

Quite a few people here report getting anxious even when taking their BP themselves:

https://www.innerhealthstudio.com/phobia-taking-blood-pressu...

I'm one of them. I bought a device with memory and covered the screen with a piece of card. Then I take BP for two weeks and ignore the first few days' readings. I seem to get used to it after a few days. This gets me readings that are very close to 120/80.

I've had anxiety about blood pressure ever since running for an appointment, while being on the first day of a new job when I was really amped up, and so (of course) had a dangerously high reading. I still remember the guy's eyes widening as he looked at the screen. Ever since then I've hated having BP taken and I can feel my BP and pulse increasing the moment I step into a doctor's office. Fortunately my doctor understands and doesn't try to push pills on me.

I wish there were some way of measuring BP without knowing it's being done. The act of measurement can greatly affect the result, which is counter-productive in several ways (not the least of which is un-needed anxiety).

York Cardiologist on Youtube is good on BP, and why apparently high BP should not automatically mean pills, although undoubtedly it sometimes should. (Usual disclaimer: this is not medical advice, ask your doctor about your specific situation.)

johnfn• 2 years ago

I remember when I was a kid, the doctor thought that my blood pressure was too high. Of course, I was just anxious because I knew they were going to give me a shot. What kid wouldn't be?? He took it again after I got the shot and it went back down to normal.

badwolf• 2 years ago

I spent several weeks trying to get a dental procedure, where the dentist flat out refused treatment because my BP was high, and every subsequent rescheduling was higher and higher and higher every time. Got a note from my PCP - my dentist still wouldn't do my crown, and was insisting that my PCP do a full screening and review. My dr just gave me some xanax to take before going to the dentist, and never had a problem since. Recently moved, and just straight up asked if I can sign a waiver or something for them to not take my BP at the dentist - new dentist was like "no problem"

das_keyboard• 2 years ago

Yeah I'm one of them. I developed a full-on anxiety disorder after my diagnosis with high BP to the point where I would get panic attacks just sitting in front of the device.

At the same time I would became obsessed with measuring BP and pulse...

My current solution besides anti-depressants and therapy is just ignoring it and trust in the pills from the doctor.

Right now I'm thinking about trying something like the Aktiia wearable to get some measurements without me knowing...

geye12345• 2 years ago

My current solution besides anti-depressants and therapy is just ignoring it and trust in the pills from the doctor.

Look up ERP (exposure and response prevention) therapy, then apply it to your fear of BP. I did that, it helped a lot.

timrichard• 2 years ago

I take BP readings for someone who gets anxious about them too. The system we've arrived at is that I play music that relaxes them during the readings. They don't look at the numbers. The first one will be high, so I usually ignore it. I take several readings, look for a couple of consistent ones, then discard any outliers.

geye12345• 2 years ago

Trying to relax always makes me more anxious since it reinforces the idea that there's a danger to be avoided. Over time I've learned the techniques of ERP, which basically does the opposite.

running1013• 2 years ago

Try the 4-7-8 Breathing technique while you are traveling to and right before you take the reading. Also just focus on something else like counting things on the wall while they take it. Mine has been high when I take it at the Dr office. But at home fine. I think tried the 4-7-8 Breathing technique this last time and it read normal at the dr office.

geye12345• 2 years ago

Replying to my own comment, but it looks like there's at least one device on the market that measures BP without the wearer knowing it's being done, the Aktiia Optical Blood Pressure Monitor.

Cost about $250-300. It's not available in the US right now officially, though it's cleared in several European countries. I don't know if it's legal to import. If it is, I may well do so.

Regrettably it has a cloud connection.

jeffreyrogers2• 2 years ago

Wearing a waffle pattern shirt can also make the reading high. My blood pressure is 20 points higher if I wear a waffle pattern shirt than if I take it off.

sieste• 2 years ago

That sounds like the guy who thought he had a leather allergy because whenever he woke up with his shoes still on he had a terrible headache and felt nauseous.

jeffreyrogers2• 2 years ago

It only happens with waffle pattern shirts and changing shirts causes a consistent decrease in blood pressure measurements. My doctor pointed it out when I got a physical because he'd seen the same thing before with other people.

unsupp0rted• 2 years ago

"If you are consistently measuring blood pressure with an unsupported arm, and that gives you an overestimated BP of 6.5 mmHg, that's a potential difference between a systolic BP of 123 and 130, or 133 and 140—which is considered stage 2 hypertension,"

Okay, but that's a small and borderline difference?

atahanacar11• 2 years ago

Yet another medical topic being discussed on HN, with comments full of disinformation and skeptics that think they've noticed something new that doctors have missed. Remember people, don't take medical advice from HN.

rscho10• 2 years ago

Those topics are fascinating. They reflect how a pretty well-educated population subset thinks about healthcare. It's almost always entertaining!

atahanacar11• 2 years ago

Definitely increases my BP though. Imagine someone ignoring their own health problems because they believed what a HN commenter said.

Dove2• 2 years ago

I am a skeptic about the diagnostic criteria for hypertension, and especially about low targets for management. Cochrane did a meta review not long ago that made it sound like the signal was pretty weak below about 160/100 (as you might expect, if the measurement wasn't very accurate, which I don't think it is). I'm not saying it's not dangerous at much higher levels, but if you're freaking out at 140/90 because a chart says STAGE TWO, imo you can take a chill pill.

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...

(Disclaimer - I am not A doctor, and I am definitely not YOUR doctor, just an interested party who thinks the science smells funny.)

mike_hearn• 2 years ago

Not surprised to hear about Cochrane's results. The science does smell funny. I read a bunch of hypertension papers this last year (I have a home machine and wanted to know how to interpret the results). Beyond the fact that inter-reading repeatability is very poor and a lot of the explanations are very ad-hoc ("fear of doctors" etc), there are other issues.

First problem: natural variance across healthy people is huge. Doctors have a target they think everyone should hit but it's just a gross average, they don't seem to take into account the possibility of genetic variance at all.

Second related problem: it's common to be told what a healthy BP is for an "adult" although BP averages for men and women are quite different, and BP is also heavily affected by age (controlling for health).

Third problem: correlation is not causation. It's a cliché because it's a real issue. The public health community is prone to blurring the line between "two variables are found to be related in a study" and "one therefore causes the other" without doing the work to prove causality, and when I went looking for what studies established BP->cardiovascular disease causality it was remarkably hard to locate firm evidence. It could easily be the other way around. Indeed in most hydraulic systems it's understood that pressure is the result of other mechanisms and under/over pressure is the result of malfunction in pumps or piping. In healthcare they argue it's the reverse: that over/under pressure is the cause of malfunction elsewhere. There's probably a circular relationship but all the material targeted at regular people makes strong claims of causality when the underlying literature seems far less certain.

Fourth problem: perhaps unsurprisingly given the third problem I found studies where people were put on anti-hypertensives and there was no improvement. Actually I read one study where the treatment outcome was purely negative: there was no effect on heart disease or other outcomes of interest but there were lots of patients who fainted due to excessively low BP. This study seemed reasonable well constructed but the negative outcome didn't seem to reduce the field's certainty in anything (a super common problem in public health). Doing trials like this is hard because any time anti-hypertension drugs fail to work it's interpreted as evidence that the damage was already done earlier in life thus requiring ever longer studies to detect.

Fifth problem: a lot of the underlying scientific claims trace back to one longitudinal study in a single village in Japan, done decades ago. It's remarkable how often you follow citations and end up back at this dataset. When you look at what the study did it's kinda sketchy and not particularly convincing, but because the BP->CVD link is hypothesized to be a very slow acting effect it takes a huge effort to collect data. The field seems to be caught in a loop where they exaggerated their confidence early, so now there is not seen to be much point in doing better studies because it'd take years (bad for your career) and why study something that's already "known".

Dove2• 2 years ago

I appreciate this detailed write up. Thank you for taking the time!

rscho10• 2 years ago

Pressure cuffs are sensitive to many factors outside blood pressure and are are pretty imprecise: news at eleven!

m463• 2 years ago

every time I get my blood pressure measured, my arm hangs on some scaffolding thing the blood pressure cuff hangs from. not even an armrest. Height is also not really standard.

that said, arm was not in my lap, and not hanging freely at my side.

crtified• 2 years ago

Putting aside the implementation technicalities, which I know nothing about, I'm convinced that markedly superior outcomes will be driven by something (e.g. watch-like devices) that captures entire weeks worth of regular BP readings across all times of day and night to provide a significant body of data.

lofaszvanitt• 2 years ago

What a world we live in. Dangerous times.

wnmurphy• 2 years ago

I'm always amazed at how many nurses take your BP with your legs hanging off of the side of a table, back unsupported.

dillydogg2• 2 years ago

One of my attendings has a running joke where he takes fresh interns in July and tells them "I will take you to <most expensive restaurant in my city> if you can take this patient's blood pressure correctly." He's been doing this for 30 years and no one has been treated to dinner yet. He's looking for the standard rest time, arm at heart level, everything.

Etheryte• 2 years ago

After reading both the article and your comment I have to say I'm somewhat confused. I don't think I've ever had a medical professional not take all the right steps when taking a reading, is it common in some context?

dillydogg2• 2 years ago

I've never seen a physician take the 5 minutes of the patient resting with their arm at heart level, personally!

TexanFeller2• 2 years ago

I have long arms which I think makes the difference more pronounced. I see a much larger difference than most people if my arm isn't supported at heart level.

georgeburdell• 2 years ago

Aside from this, a lot of medical professionals, particularly the PA’s, seem to be very low knowledge on how to identify the veracity of blood pressure readings. I’ve multiple times had to ask them to retake the blood pressure when the reading was very high or low. It was really surprising the first time it happened and made me wonder what else is getting misreported

throwbmw• 2 years ago

People shouldn't worry about accuracy too much. Everybody in healthcare knows about the problems in various measurement methods as well as individual responses to measurement anxiety and the physical and emotional state you are in that particular time. The only accurate measurements are direct measurements through an arterial catheter which is a very invasive procedure. Routine clinic measurements are used only to have a general idea about trend and secondly to catch severely high BP which is usually due to a secondary disease. Also, if BP is high above a certain limit it is significant regardless of if you took rest for 5 minutes and other precautions. Because if BP is high the normal BP regulating system should kick in and lower it regardless of the cause. With advancing age and hardened arteries this response becomes less optimal and you need the support of anti hypertensive medicines. You can see this in real time in patients under anesthesia. A young healthy patient would have an initial peak in response to pain or other surgical stimulus but they will be able to lower it either spontaneously or with minimal outside intervention. Whereas in older individuals much more effort is required to control and lower the BP. The general trend has been to treat both hypertension and diabetes early because the microvascular complications start much earlier before they become apparent clinically.

scotty79• 2 years ago

Does the body of a patient under anesthesia react to (unfelt?) pain by raising blood pressure?

xpe4• 2 years ago

No, “everybody” in healthcare does not know this. I have learned to be skeptical and not to assume any particular level of statistical competence in the healthcare field.

lo_zamoyski2• 2 years ago

Nurses/healthcare professionals often take the patient's blood pressure and heart rate just as soon as they enter the room after walking and moving about. Wait a few minutes and the measurement changes significantly, giving you a better indication of actual heart rate at rest.

Cthulhu_2• 2 years ago

If they don't then the education system (and common sense) has failed them.

xpe4• 2 years ago

The only accurate measurements are direct measurements through an arterial catheter which is a very invasive procedure.

No. Accuracy isn’t all or nothing.

If one means “most accurate” then just say that.

xpe4• 2 years ago

Meta-analysis here: https://pubmed.ncbi.nlm.nih.gov/28750701/

There are also newer techniques, such as resonance sonomanometry: https://www.caltech.edu/about/news/caltech-team-develops-fir...

mannyv• 2 years ago

4-7 mm of inaccuracy is irrelevant.

UncleOxidant• 2 years ago

Wasn't there a recent article that said it was best to measure blood pressure lying down?

fsckboy• 2 years ago

Commonly used arm positions can overestimate blood pressure readings

are these arm postitions used so commonly that what we call high or low blood pressure is based on them?

99_00• 2 years ago

The study tested two incorrect positions and the correct position. It “confirmed” that the correct position is correct.

So it’s nothing new, and not anything that isn’t in practice and part of basic procedure

And they underscore the importance of adhering to clinical guidelines calling for firm support on a desk or other surface when measuring blood pressure, the investigators add.

mock-possum• 2 years ago

I always figure it’s just a good method to track changes in trends - not so much is this reading accurate, but how does it compare to the last 20 you’ve taken - has your blood pressure been trending upwards? Might want to get that looked at.

sivm• 2 years ago

In my experience in the US, nurses at primary care practices don’t really care and have no passion for their profession and the younger doctors are Anki flashcard veterans who could be replaced with a LLM and probably have the same outcome. Even DOs act like MDs these days- I guess it is easier to just write a prescription than advise traditional diets.

120/80 is an ideal blood pressure based on studies that show an association between elevated readings and an increased risk of heart attacks and strokes. More than half of humanity has a higher blood pressure than that. I believe most would have much lower readings if they stopped eating the trash food that capitalism has produced.

Ylpertnodi• 2 years ago

I jog, cycle, other light sports, work is walking a fair bit, and i eat well - zero trash, and even with meds I'm still way above 120/80. Heredity seems to play a part (my guess).

lordnacho• 2 years ago

Maybe someone could take the time to explain how it actually works. Somehow I missed it in my engineering education.

You have a bladder that goes around someone's arm, and it is inflated. It slowly deflates, and somehow this tells you the pressure in the blood vessels inside the arm.

But that raises some questions:

1) Your arm isn't just blood vessel, most of it is bone and muscle. And fat.

2) How does the inflation help? What about the deflation?

3) What is on the other end of the device?

Smaug123• 2 years ago

The cuff inflates to constrict the brachial artery until it is completely closed (i.e. the cuff detects no pulse, i.e. the external pressure from the cuff exceeds the maximum systolic blood pressure). Then it deflates until it detects a pulse as blood once again is able to force through the cuff's constriction (this threshold tells it the systolic blood pressure). It continues deflating until once again it detects no pulse (i.e. the minimum diastolic blood pressure exceeds the pressure exerted by the cuff).

dpeckett• 2 years ago

Measuring at a single point in time is so inaccurate due to things as simple as circadian variation of blood pressure (morning surge, night time dipping, etc). Not to mention acute stressors, arm positions etc. It's hard to put any weight on a single reading, and tbh doctors already know this.

After some hypertension issues last year I bought an inexpensive ambulatory monitor (Contec ABPM50) for experimenting. Turns out the biggest contributor was likely undiagnosed sleep apnea, infact research suggests up-to 50% of essential hypertension cases are probably apnea related [1].

Sleep apnea is ridiculously common and significant apnea in young/middle aged individuals (particularly women) is associated with an up-to 5x increase in all causes mortality [2].

If have poor sleep, mental health issues (PTSD/anxiety/depression) and borderline/hypertension you should absolutely order something like a WatchPAT test. The odds of it coming back positive are probably 80%+. The STOP-BANG questionnaire is also pretty good: https://www.mdcalc.com/calc/3992/stop-bang-score-obstructive...

1. Chaudhary SC, Gupta P, Sawlani KK, Gupta KK, Singh A, Usman K, et al. Obstructive sleep apnea in hypertension. Cureus [Internet]. 2023 Apr 27; Available from: https://doi.org/10.7759/cureus.38229

2. Lavie P, Lavie L, Herer P. All-cause mortality in males with sleep apnoea syndrome: declining mortality rates with age. European Respiratory Journal [Internet]. 2005 Feb 28;25(3):514–20. Available from: https://doi.org/10.1183/09031936.05.00051504

jjallen• 2 years ago

If it’s happening systematically to almost everyone than the whole system has been calibrated to that. Probably want measurements to be slightly high to err on the side of caution anyways.

nottorp• 2 years ago

Humm. Does it matter?

Just settle on a standard arm position for the measurement and set the standards for that position.

I mean, you could even set the standard to be measured at the neck while the patient is hanging upside down and still the average would be average and the outliers would be outliers.

groodjorb• 2 years ago

TLDR: Rest arm on table while taking a reading. Don't let your arm hang, unsupported, or flop on your lap. (15th paragraph has the meat of the article).

krisroadruck• 2 years ago

Found out I had been worried about my blood pressure for no reason for close to 4 years. When I moved I brought it up to my new doctor and he said "what color was the cuff". Turns out they were using one entirely too small for my arm, which wouldn't you know it gives false-high readings. Turns out my blood pressure is frickin perfect.

Commonly used arm positions can overestimate blood pressure readings: study

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