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Build Your Own ECG
Jason writes "I finally finished documenting my $4 home made electrocardiograph (heart monitor). If anyone is interested or wants to build one for themselves, please come by and take a look. Makes me wonder why medical care costs so much. :)"
This could make a great gnome toolbar applet. Then I could enjoy watching my heart race when I accidently type 'rm -rf *' in the wrong directory!
when you can tell me how to build one of 'dem four dollar defibrillators. With my steady diet of coffee, butter and bacon, heck, that thing would pay for itself.
And to think that today I used $4 to buy two Nacho Cheese Steak Chalupas at Taco Bell. While you were out trying to save your heart, I was slowly beating it into submission with slightly substandard but confusingly delicious Fast Food(TM).
Small potatoes make the steak look bigger.
Yea, but does it interpret the data. That's one of the big expenses according to her: have the cardiologist examine the data and give his opinion. Since it's all waveform stuff, I wonder how much of that could be automated in the future?
This space for rent.
I'm pretty sure that $4 is in fact less than $10.
PLEASE be careful with ECG or EEG circuits, especially if you're planning to use an oscilliscope to see the wave or a data acquisition board to log the data. The pads and the gel used to adhere them to the skin and lower the resistance to get a good signal can sometimes cause current to flow into the body, especially if the circuit is not optoisolated.
Normally, the skin resistance is high enough to make the current flow negligible; however, when the pads are on, the resistance in the path is very low, and you could seriously injure or kill yourself if even a small amount of circuit flows 'back' through the electrodes.
Professional ECG machines usually have a lot of protection circuitry on their front ends (the instrumentation amplifiers) as well as between the amplifier and the ADC/output circuits to prevent this from happening. This is obviously even more critical in line- (i.e. 110V or 220V-) operated devices.
Karma: Excellent Birds (mostly as a result of listening to Laurie Anderson)
Oh don't get me started on medical equipment, [read: I'm going to get started on medical equipment]
Being disabled (SMA type 2, A type of MD, Donate to MDA!) I deal with medical equipment a lot, less then some in more critical situations, but more then your average user.
It's outrageous the markup medical tag gives to an item, one of the most outlandish of them that I saw was a flag, a metal mounting bracket, fyberglass rod, and cheap neon flag. You know the kind, sold in the walmart bike department for a measly 3$
Do you know how much they wanted at a medical store? No you dont.... 18$
So the price of "medical" is 15$ on top of 3$ It's insane.
You can buy an Ok car for the price of an electric wheelchair. And that's just for what's on the low end.
How exactly are people who can't walk suppossed to affoard this shit? Sure it's possible, and often times picked up by the government (thank god)
And if you're not covered, forget footing this bill your self, unless you've got cash to burn. And it's not like the freedom of mobility is important or any thing. Just one of life's liberties some people take for granted.
"I wish I could sit all day"
Fuck you buddy
Grrr, can you tell I'm bitter?
And then theres red tape. I've been using this same wheelchair for several years now, it needs replaced. But fighting for them is a nightmare. So much paper work.
Computational Madness in a round package.
Congrats on what you've done so far...if you want to take the next step:
Higher-quality ECGs systems don't use generic op-amps, they use special devices called instrumentation amplifiers that are able to reject common-mode signals at the inputs really well. Turns out then when you place electrodes on the skin, the skin between the electrodes acts like a crude battery (we're full of electrolyte after all!) and you get a large, shifting potential difference between the two electrodes that can drown out the millivolt-range ECG signal.
Oh and by the way, the electrodes and wires will make great radio antennas (esp for 60 hz noise)! Check out the AD624AD instrumentation amp from Analog Devices.
A disgustingly large amount of our medical expenses goes to malpractice insurance, and mostly to protect from one of the millions of malpractice cases that never should have been that occur each year. Granted, the ability to sue for malpratice *is* a good thing. However, it is grossly misused, and results in higher medical bills for all.
Not to say that's the only factor... but that's one of them.
---^v---^v---^v-------
Eeep...eep...eep..eeeeeeeeeeee
time of death 927PM CST.
Damnit jim I'm a doctor not a webserver admin..
Partnership for an idiot free America!
EXACTLY! Just what I was thinking when I saw this.
.1 amp to kill you dead, and about .01 amp can interfere with normal heart operation. Normally, skin runs about 10 to 100 kohms resistance - to get 10 milliamps you would need about 100 to 1000 volts delivered across the chest.
Kids, DO NOT TRY THIS AT HOME.
Real medical gear has full galvanic isolation - that means there is NO current path that goes from the patient's body to the equipment - the signals pass through either an isolation transformer, an optocoupler, or a capacitive coupling. That way, any ground leakage in the equipment won't fry the user.
It takes about
When you put the gel on, you reduce the resistance to a few hundred ohms. Now you need only a volt.
Normal consumer equipment can have "leakage currents" - places current shouldn't be flowing but is. You hook your home-brew circuit up to the printer port on your PC, and maybe you are OK. Then one day, while screwing around with it, a cap starts to fizzle in your power supply, or maybe you reach up to adjust your monitor, or maybe you put your foot on the ventilation register. Then you get to start (posthumously) on the 6 o'clock news.
At a MINIMUM, you should power the circuit with a nine volt battery, and communicate with the PC via an opto-isolated RS-232 link.
Even better, splurge and get the real medical isolation amplifier modules. Yes, they will cost a bit more than US$4, but then, if that is all the value you place on your life....
On second thought - go for it! And make sure you clip the ground lead off your computer's power cord while you are at it. And do it in the bathtub - that will help shield the fnord rays out.
www.eFax.com are spammers
There are several reasons healthcare is so expensive.
1. Litigation. Does the phrase "malpractice insurance crisis" ring a bell?
2. A side effect of (1.) is something called "CYA medicine". Ever receive a chest CT because your heartburn just might be a pulmonary embolism? It happened to me just recently.
3. Failed accountability. This one takes a bit more explaining. Ever bother to look at your bill? Of course not. Why? Because chances are, the insurance company pays it. Aha! You say. What if I'm not insured? Well then, many people who aren't insured "spend down" and go on Medicaid. Once more, nobody looks at what Medicaid is being billed, except for the hardworking beurocrats (cough)bull***(cough). Only the very narrow slice of the population that is "self paying" actually looks at a bill (more on thatlater) You would think that insurance companies would be on guard for their bottom line, but corporate inefficiency is often no better than government inefficiency.
4. Complex and inefficient billing. Health care is one of the few businesses where you receive service at a single location, yet billing goes from subconractors directly to insurance companies or patients. Worse yet, billing from some contractors takes weeks, or even months. Yuck! Imagine if every business worked like this. Imagine getting your car fixed, and you get bills from the mechanic, the parts department, and the oil supplier spread out over 2 months. It's not just inconvenient. It actually hinders your ability to make financial plans because you don't know what's coming. And why don't you know what's coming? That leads us to...
5. ...Secrecy. That's right. Secrecy. Try to call up a hospital and ask them for their price list. Chances are, you'll get the same answer I got: "That's on a computer and it's confidential". I was transferred to a manager who had her phone on voicemail. In retrospect, I should have known I was in trouble when the phone tree had "press 2 if you're an attorney". This is probably one of the biggest reasons healthcare costs too much. Sure, there are several hospitals within driving distance, but if I think I am going to need an exam that is likely to involve half an hour with a doctor, some medication, and an x-ray... I have no idea who charges the least for an x-ray, or what the hourly billing rate is for a doctor, or what the average examining time is for diagnosing a condtion. We have more accountability at the garage than we do at the hospital (Chilton's guides, posted labor rates, etc).This alone is probably the single biggest factor driving up healthcare costs. Lack of pricing information makes comparison impossible, resulting in a virtual monopoly even though there are multiple companies. So, what did I do? I gave up and paid a price that I could not verify as accurate because I knew that the only way to get the price list was to make a federal case out of it, and spend 100 times more in legal fees than my bill was.
6. Vested interests. You can call me a conspiracy theorist if you like, but I think various interests want the price of healthcare to skyrocket so that they can use that as an excuse to socialize it. The corporations actually secretly like the idea of socialized medecine, because then they get to become government agencies. If you are a corporate sleazeball, the next step up is to become a government sleazeball; the perks are just that much better. You can just hear them salivating.
Want to fix healthcare? Fine. Require providers to give one bill in a timely manner--no pass-throughs to subcontractors. Require providers to post price-lists online if they have a website, or to make price-lists available to the local libraries. Require employers who insure their employees to provider high deductable insurance. There should be no claims or forms until annual out-of-pocket costs exceed 10% of your annual pay. Place a cap punitive damages, as many have suggested.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
How to build an ECG for $4:
parts list:
* one surplus patient cable with sensor and plug ($4 on ebay)
instructions:
* Plug the sensor into a strip chart recordor or heart monitor you might have lying around the house. For instance I found and old Hewlett-Packard model 78534C EKG and dual-channel pressure monitor.
You're done! It's THAT EASY! And just FOUR BUCKS!
Tune in next week when I tell you how to build your own x-ray machine for the cost of some X-ray film (you might need to find some medical equipment you might have laying around the house to complete the project).