The thing is that I can get just as good if not better ones (metal) for $7 all day long, and not have to spend time sourcing and assembling materials, and I don't even have to leave my house to do it.
I'm not sure what you are buying, but it wouldn't surprise me if they were done in a factory that does medical grade quality control. While the odds are a medical problem from a non-medical grade stethoscope seem low, it still seems a couple bucks is worth the price. (if we are talking thousands I'd ask for a deeper drive into what that really gets you)
$100 for a somewhat specialized, durable medical device that has to meet regulatory standards and will be used daily, possibly for years, by healthcare providers to do patient assessments?
A 3D printed option is going to require a 3D printer, appropriate filament and should be unit tested to ensure it's within spec. The durability is going to be suspect no matter what. It's an awesome project and I'm sure would be a welcome addition to the 'boostrap humanity' catalog of 3D printed parts, but for everyday doctors plunking a hundo on a good tool is going to be a no-brainer.
> $100 for a somewhat specialized, durable medical device...
And one which is treated as a status symbol, at that. Part of the reason a good stethoscope costs more is because it looks nicer, not just because it works better.
A commercially sold hospital stethoscope is a legally marketed medical device made under a manufacturer quality system, with labeling/instructions, device listing/registration obligations, adverse-event/complaint processes, cleanability expectations, liability, warranty, consistent materials, and repeatable acoustic performance.
An open-source 3D-printed stethoscope is a cool project, but unless it is produced and controlled as a medical device, it is not equivalent to what hospitals are buying for daily patient care.
Personally, if I was a hospital or a doctor, it would be a no-brainer for me to go with the commercially sold stethoscopes. All those factors I listed above, if neglected, can end up costing a lot more in terms of consequences. I would rather pay a fixed extra overhead price per unit to sleep well, knowing I don't have to worry or think about those factors at all. And, I would assume, most of the patients would be in favor of that as well.
I know nothing of this, but it looks like stethoscopes are Class 1 medical devices with 501(k) exemption, and fall under the "Good manufacturing practices" guidelines of Quality System Regulation (21 CFR 820), but seems pretty squishy.
Years ago I had my blood pressure taken by a nurse; this was when they did it manually, squeezing the pressure cuff bulb by hand and listening with a stethoscope. The doctor came in later, saw the numbers and frowned, and took my pressure again. She (both were women) ended up with a reading much more within my normal range.
I asked, joking, “So are you just better than her?” “No,” my doctor replied, “She’s better. She gets more practice. I have a better stethoscope.”
The pressure cuff + stethoscope combo is called a sphygmomanometer. It's a pretty fascinating piece of technology: A heartbeat is only audible in the earpiece when the cuff is compressing between someone's systolic and diastolic pressure.
To use it, you get the cuff pressure high enough that you stop hearing a heartbeat in the earpiece. Start releasing pressure slowly. As it comes down, take note of where on the dial you start hearing the heartbeat. That's systolic pressure. Keep listening, and take note of where you stop hearing the heartbeat. That's diastolic pressure.
And if you use a mercury sphygmomanometer, you can actually see those pulses appear and then disappear. (It's harder to see them with a gauge-based one.)
I have a much higher BP when I first go to the office than after I'm sitting in the exam room for a bit.
Usually they call me back to the hallway where they check my weight, then have me sit in a chair and check my temperature, pulse ox and BP, with maybe only a minute sitting down before they do the BP check. My BP is usually in the "hypertension" range there.
But, if they come back to the exam room after I've been sitting in that quiet room for 5 or 10 minutes and check my BP , it's almost always in the "normal" BP range (same as what I see when I check it at home).
Doctor calls it "white coat hypertension", I call it "rushed BP check in the hallway".
People buying stethoscopes tend to be reasonably affluent. Some of the pricier ones just look better and people usually buy them when you get into med school (at least this was the case for me), it's somewhat symbolic so why not splurge.
There does seem to be a difference in quality though. It's much easier to hear the important things with my littman than with the cheap generic stethoscopes I usually find lying around in clinics.
It’s funny, most physicians agree that the cheap disposable stethoscopes in isolation rooms are the best, mostly because they are so loud it’s difficult miss anything with them. However, I am not a cardiologist so they may have a different opinion.
I've actually found them pretty terrible. I can't hear subtle findings at all with those. My usual stethoscope is an older-model Littman Cardiology III with stiff rubber and a dual pediatric-adult head. I've had it for over 25 years.
I guess it's different strokes, because I can definitely hear subtle sounds much easier with them. In fact normal sounds sound like it is going to blow out my ears. The only issue I have is consistency; it's difficult to gauge how much something has changed over time with different stethoscopes, especially pulmonary edema and wheezing.
I think this is a good point, insofar that how bacterial resistant the stethoscope is relevant. Stethoscopes made of stainless steel are going to beat anything 3d printed by a significant margin.
It definitely doesn’t help that prints from filament printers are very porous, 100% infill or not. Maybe sealing it with epoxy after printing would help?
This seems like another case where the hobby has discovered the 3d printer hammer and forgot that cnc tools (lathe, milling machines) are often better and faster for the job. Or if plastic is what you want injection molding is something you can do on a hobby scale and it is much better (but unlike the others this isn't something you can go from CAD to widget)
The thing is that I can get just as good if not better ones (metal) for $7 all day long, and not have to spend time sourcing and assembling materials, and I don't even have to leave my house to do it.
I'm not sure what you are buying, but it wouldn't surprise me if they were done in a factory that does medical grade quality control. While the odds are a medical problem from a non-medical grade stethoscope seem low, it still seems a couple bucks is worth the price. (if we are talking thousands I'd ask for a deeper drive into what that really gets you)
Respectfully, as this is HN, I do not believe that is the purpose of the posted Github repository.
I was shocked to see that a "brand name" stethoscope is $100+ and even generic ones are $30.
I'm shocked that you're shocked lol.
$100 for a somewhat specialized, durable medical device that has to meet regulatory standards and will be used daily, possibly for years, by healthcare providers to do patient assessments?
A 3D printed option is going to require a 3D printer, appropriate filament and should be unit tested to ensure it's within spec. The durability is going to be suspect no matter what. It's an awesome project and I'm sure would be a welcome addition to the 'boostrap humanity' catalog of 3D printed parts, but for everyday doctors plunking a hundo on a good tool is going to be a no-brainer.
> $100 for a somewhat specialized, durable medical device...
And one which is treated as a status symbol, at that. Part of the reason a good stethoscope costs more is because it looks nicer, not just because it works better.
> has to meet regulatory standards
Genuinely curious, what standards exactly, for a stethoscope?
A commercially sold hospital stethoscope is a legally marketed medical device made under a manufacturer quality system, with labeling/instructions, device listing/registration obligations, adverse-event/complaint processes, cleanability expectations, liability, warranty, consistent materials, and repeatable acoustic performance.
An open-source 3D-printed stethoscope is a cool project, but unless it is produced and controlled as a medical device, it is not equivalent to what hospitals are buying for daily patient care.
Personally, if I was a hospital or a doctor, it would be a no-brainer for me to go with the commercially sold stethoscopes. All those factors I listed above, if neglected, can end up costing a lot more in terms of consequences. I would rather pay a fixed extra overhead price per unit to sleep well, knowing I don't have to worry or think about those factors at all. And, I would assume, most of the patients would be in favor of that as well.
What standard exactly, for a stethoscope?
I know nothing of this, but it looks like stethoscopes are Class 1 medical devices with 501(k) exemption, and fall under the "Good manufacturing practices" guidelines of Quality System Regulation (21 CFR 820), but seems pretty squishy.
Years ago I had my blood pressure taken by a nurse; this was when they did it manually, squeezing the pressure cuff bulb by hand and listening with a stethoscope. The doctor came in later, saw the numbers and frowned, and took my pressure again. She (both were women) ended up with a reading much more within my normal range.
I asked, joking, “So are you just better than her?” “No,” my doctor replied, “She’s better. She gets more practice. I have a better stethoscope.”
The pressure cuff + stethoscope combo is called a sphygmomanometer. It's a pretty fascinating piece of technology: A heartbeat is only audible in the earpiece when the cuff is compressing between someone's systolic and diastolic pressure.
To use it, you get the cuff pressure high enough that you stop hearing a heartbeat in the earpiece. Start releasing pressure slowly. As it comes down, take note of where on the dial you start hearing the heartbeat. That's systolic pressure. Keep listening, and take note of where you stop hearing the heartbeat. That's diastolic pressure.
Using one feels kind of magic.
And if you use a mercury sphygmomanometer, you can actually see those pulses appear and then disappear. (It's harder to see them with a gauge-based one.)
I have a much higher BP when I first go to the office than after I'm sitting in the exam room for a bit.
Usually they call me back to the hallway where they check my weight, then have me sit in a chair and check my temperature, pulse ox and BP, with maybe only a minute sitting down before they do the BP check. My BP is usually in the "hypertension" range there.
But, if they come back to the exam room after I've been sitting in that quiet room for 5 or 10 minutes and check my BP , it's almost always in the "normal" BP range (same as what I see when I check it at home).
Doctor calls it "white coat hypertension", I call it "rushed BP check in the hallway".
Or, maybe you have "white coat syndrome" [1]. This is closely related to "pretty lady syndrome".
[1] https://en.wikipedia.org/wiki/White_coat_hypertension
They can become a lot more expensive than $100, but the difference between a Littman Cardiology and the $15 EMT student stethoscope is night and day.
> Currently, the stethoscope resulting from this project functions as well as the market gold standard, the Littmann Cardiology III
If this is true, it's a major achievement.
People buying stethoscopes tend to be reasonably affluent. Some of the pricier ones just look better and people usually buy them when you get into med school (at least this was the case for me), it's somewhat symbolic so why not splurge.
There does seem to be a difference in quality though. It's much easier to hear the important things with my littman than with the cheap generic stethoscopes I usually find lying around in clinics.
My daughter's toy stethoscope has actual tubing, some sort of diaphragm, and that seems to work reasonably well!
I'm not surprised good results are available for a few dollars.
It is somewhat of a critical tool, so you don't wanna be checked by a doctor who made their own stethoscope or got one for 3 USD on AliExpress.
It’s funny, most physicians agree that the cheap disposable stethoscopes in isolation rooms are the best, mostly because they are so loud it’s difficult miss anything with them. However, I am not a cardiologist so they may have a different opinion.
I've actually found them pretty terrible. I can't hear subtle findings at all with those. My usual stethoscope is an older-model Littman Cardiology III with stiff rubber and a dual pediatric-adult head. I've had it for over 25 years.
I guess it's different strokes, because I can definitely hear subtle sounds much easier with them. In fact normal sounds sound like it is going to blow out my ears. The only issue I have is consistency; it's difficult to gauge how much something has changed over time with different stethoscopes, especially pulmonary edema and wheezing.
Our one that DIY'd one like one would do a dosing rod in their garage.
Well-formed sentence one dosed for make benefit understandability not garage DIY'd one?
Written on ether?
You probably pay for tests and that the company has to be audited for medical diagnostics standards
Is that a lot or a little?
This "recipe" produces them for $5 ... that's 5% of the market price.
Assuming equivalent capabilities and longevity.. I know physicians who have used their "20x too expensive" Littmann for 30 years.
À lot
What's the price per use compared to a standard industrial metal one?
No pictures? Missed opportunity. Seems cool though!
The linked paper has some pictures: https://doi.org/10.1371/journal.pone.0193087
https://journals.plos.org/plosone/article/figure?id=10.1371/...
Do the design and materials take into account how well it can be sterilized?
I regularly wipe my stethoscope, but I have never sterilized it. I doubt many would survive an autoclave.
Never seen a UK doctor or nurse attempt to clean, much les sterilize, one.
There are disposable, single-patient stethoscopes, but I've seen my Dr do a casual wipe with an alcohol swab often enough...
I think this is a good point, insofar that how bacterial resistant the stethoscope is relevant. Stethoscopes made of stainless steel are going to beat anything 3d printed by a significant margin.
It definitely doesn’t help that prints from filament printers are very porous, 100% infill or not. Maybe sealing it with epoxy after printing would help?
This seems like another case where the hobby has discovered the 3d printer hammer and forgot that cnc tools (lathe, milling machines) are often better and faster for the job. Or if plastic is what you want injection molding is something you can do on a hobby scale and it is much better (but unlike the others this isn't something you can go from CAD to widget)
The usual procedure is to wipe with 70% ethyl alcohol.
Instructional video: https://youtu.be/u-KNTc0POLA
Are sthethoscopes passive or active devices?
It's basically a tube that transmits sound waves from a diaphragm to your ears. Pretty much an extension of your own ears.
Nowadays they do make electronic models. Active enough, I suppose. Can even record sounds.
passive