New devices could change the way we measure blood pressure
knowablemagazine.org
knowablemagazine.org
Injuring most patients by depriving them of sleep for no good reason is felt to be justified by the chance of catching an extremely urgent problem in time to do something about it once or twice over the lifetime of the hospital.
An example of this with a lot of popular misunderstood awareness is the idea that you shouldn't sleep if you have a concussion. Preventing the patient from sleeping is detrimental to their health; it inhibits healing.
The reason hospitals do it is that their way of diagnosing whether the concussion patient has just experienced a catastrophic complication is to talk to them and see whether they are capable of producing normal language. This diagnostic mode is not available if the patient is asleep. So the patient isn't allowed to sleep.
But yeah, there’s probably different things that work the same way.
It's harder than it seems. Increased respiratory frequency can be subtle, it won't be full dyspnea every time. The signs can be missed if not explicitly looked for. Observing respirations requires a well lit room for the examination.
> But yeah, there’s probably different things that work the same way.
Sepsis diagnosis also includes assessment of mental state. Mental confusion is a symptom of sepsis. Glasgow Coma Scale is a component of Sequential Organ Failure Assessment scores: it includes talking to the patient and evaluating the coherence of verbal responses.
https://en.wikipedia.org/wiki/SOFA_score
Can't be done if the patient is asleep or sedated.
Of course, it is a coma scale after all. Actually applying it to sleeping patients though? Will get you false positives at best: even healthy patients will fail to respond verbally (-4), blink their eyes (-1) and obey commands (-1) if they're asleep. That's a maximum GCS of 9 even if you stop there. If you don't stop there, you might just get punched in the face when they are rudely awakened to the sight of you testing their pain response.
If I were to start taking measurements at random times, such as while walking or watching an action movie, the results would be misleading as they were not obtained under the same conditions as the gold standard measurements.
I would also question how accurate these new devices are. I used to use a wrist cuff BP monitor but one day I took it into the doctor's office and did a side by side comparison with my doctor's BP monitor. My wrist cuff BP monitor was reading about 20mmHg too low. I thought I had my hypertension under control but it wasn't. I've since replaced it with an arm cuff BP monitor. If I have to go to the effort of sitting and relaxing for 15 minutes to obtain a measurement, attaching an arm cuff is not much of an inconvenience.
Also I think in theory true continuous blood pressure monitoring data ought to be a lot more informative than just resting blood pressure. We may not yet have the research to really draw conclusions yet, but it should become possible to do that research relatively quickly if a whole lot of continuous blood pressure data becomes available.
24 hour blood pressure monitoring is the gold standard. Samples blood pressure every 15 minutes regardless of what the patient is doing. Even during sleep. Wearing the equipment is pretty annoying so it's not done routinely. Better, more comfortable wearables with higher sampling rates would be great.
And yes, more comfortable wearables would be grand. Blood pressure cuffs hurt: Last time I had the 24 hour monitoring, I had bruising and blisters from the cuff.
On accuracy on why take measurements continuously, I'm wondering how you see pulse measurint. Do you feel it should also be done at rest only, and constant numbers bring nothing to the table ?
However diagnosis, especially in early stages, is enhanced by more frequent testing:
"To determine the most reliable way to measure blood pressure, researchers followed 11,135 people from Europe, East Asia, and Latin America for 14 years... The researchers found that the 24-hour and nighttime blood pressure measurements provided a more accurate estimate of one’s risk for heart and vascular disease compared to the in-office readings." (1)
It is a fact that your blood pressure changes while you go about your day and while those values aren't useful for comparing a diagnosis against the standardised test, there is still value in understanding how your blood pressure changes, the duration and amount of that change and risk factors for bringing about those changes.
Furthermore similar to measuring the beating of the heart, continuous blood pressure monitoring can be an useful as indicator of other kinds of medical conditions, this would go beyond what is pragmatically possible with a 24 hour testing cuff.
If you're a person who needs to have their blood pressure checked - then you are a person who will benefit from continuous measurement.
My only qualm to telegaph: continuous indirect BP measurement is hard, and past approaches have had a limited scope. This is one of those technologies where it is wise to have an amount of skepticism.
(1) https://www.utrgv.edu/newsroom/2019/08/07-international-stud...
I hope these alternative methods are viable.
I can't imagine tracking it like your wife -- over weeks. I hope it is working out OK for her.
Anything worn on the wrist is going to be sensitive to noise either from motion or from varying amounts of light getting to the ppg sensor.
It’s not a game changer yet. Partly because of those problems, partly because there aren’t established norms for what to do with more bp data.
All that’s getting better though, I think it’ll make a difference in the next 5-10y.
Some of those real-time results might be interesting. Maybe you could cut back on the coffee a little. But there's also a natural variance because life over the course of a day or weeks that many of us would just as soon ignore and instead prefer to monitor accurately over comparatively long time intervals (week+) with at least an attempt to measure under comparable conditions. (And even then I find a fair bit of variance.)
That's a general issue I have with "quantified self" info. It's either something I know. (I didn't sleep well last night for whatever reason or I was at a desk or in a plane seat all day.) Or it's something I mostly can't or won't do much about.
Until that's solved, and I don't see how it could be, they will remain mostly useless toys to me (who am utterly lacking the discipline to enter data reliably enough for statistical analysis).
Section 5.2 is covers the direct measurements, that don't require you exist in some region of a distribution of the population. They don't offer any methods for continuous (the continuous kind) measurements that would be comfortable, which is unfortunate.
Section 5.1 covers "calibrated" methods, where you have to calibrate the device using a direct measurement, or fit within some distribution of the population, for the model to work, which will probably be a great annoyance for doctors.
I suspect it will be a while before we get continuous and accurate measurements.
60+, yeah.
Besides, a sprained ankle or whatever doesn't much affect your ability to use tech.
For as much as I would worry, the data kept insisting I was stubbornly healthy and that when I did feel poorly, it was almost always attributable to something specific I’d done recently. It made it very hard to maintain the anxieties I’d spent decades culturing, so I eventually just gave in and accepted that I was pretty darn fine and had some specific bad habits that had been surreptitiously fueling the anxieties.
So while more data might make things worse for you, that experience is not universal.
I'm surprised that the type of health data captured passively from a watch is enough to assuage the fears of any true hypochondriac. While they do capture some basic health metrics, it seems that there are many illnesses/disorders that would never be detected by the watch until they become an acute illness.
For the 45% of people with hypertension without a BP monitor, they probably aren't going to buy something 5-10x more expensive to do the same thing either.
Not to mention that it doesn't change any of the lifestyle or medical interventions we have to reduce BP.
I've just found the whole biohacking crowd to be generally misinformed and lacking foresight on this stuff. It's very simple - you can measure your BP in the morning as soon as you wake up for one week. If its high, you can get medicines or change lifestyle to reduce it. If you're interested in how BP changes with different activities, you could measure that quite easily too, or just look it up. Physical activity increases BP, weightlifting increases it a lot, and none of these temporary increases mean much for overall health. I don't see how getting some more data or a nice graph in Apple Health is going to change anything.
I think the big advantage of watch-based health monitors is that they can find problems in people that don't already know they have the problem.
You already know you have hypertension so you monitor your blood pressure, many people don't know they have it.
The same is true of non-invasive glucose monitoring if that becomes viable to add to smart watches -- you may still need to wear a continuous glucose monitor if you have diabetes to monitor your blood sugar, but the watch may be a good early warning that you have a problem.