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.
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.
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.
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.?
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.
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‽‽
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.
> 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.
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.
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.
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.
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.
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.
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.
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.
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.
> 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.
> 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.
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.
> 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.
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.
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.
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.
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.
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.
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.
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.
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.
> 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.
> 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.
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.
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.
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.
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.
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.)
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.
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.
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.
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...
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.
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.
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"
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... )
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.
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).
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.
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.
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.
>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.
> 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).
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
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!
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.
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 ?
> 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.
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.
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.
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 :)
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.
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)
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.
>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.
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.
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?
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.
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.
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.
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.
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
Readit News
No. Accuracy isn’t all or nothing.
If one means “most accurate” then just say that.
There are also newer techniques, such as resonance sonomanometry: https://www.caltech.edu/about/news/caltech-team-develops-fir...
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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.?
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Finally realized, that I was habitually late, getting to my appointments and always taking the stairs.
Don’t do that.
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.
Used to flummox me until I bought my own meter, they can be like $30.
- 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.
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.
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...
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.
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.
In situations where blood pressure really matters, we aren't playing around with the cuff and hand positioning. The patient gets 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.
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.
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.)
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.
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...
Look up ERP (exposure and response prevention) therapy, then apply it to your fear of BP. I did that, it helped a lot.
- 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... )
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.
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).
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.
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.
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.
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).
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
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!
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.
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.
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.
Hopefully you get lucky. Why address cancer, insulin resistance or stroke risks early?
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.
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 :)
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.
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.
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.
> 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.
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