Build my own machine

[mintra]

I want to make a APAP machine, don't really care about patents as I am not going to sell it. It may be useful to look at some existing machines.

I guess we are talking about a couple of fans controlled by a small micro controller.

Anyone got any ideas or seen if their are any plans on the internet.

[Fredxx]

OK, first off - I really wouldn't recomend this as a way to self treat!

Secondly, Whilst I am an analyst, engineer and designer of "intelligent machines", I am not an expert in CPAP machines.

Right, disclaimer over, now onto the engineering...

Starting with the assumption you mean you want to build a CPAP machine, rather than an APAP machine...

If you are wanting to make a machine which delivers a constant pressure flow of air, the best solution is delivery with a centrifugal fan rather than any axial ones. It is extremely difficult to control pressures with axial fans.

The lowest tech solution would be to build a rig with a regulated power supply to control the fan, and to calibrate the delivered pressure with a water column manometer, ensuring that you have a rig capable of delivering the right degree of flow (leak-rate) that your chosen mask has. This set-up would need frequent re-calibration to check the delivered pressure.

To increase the sophistication, you could build in a pressure transducer on the delivery side of the device to constantly monitor the delivered pressure and adjust the machine appropriately. There would need to be some consideration as to whether you damp the adjustment to allow the fan to deliver a pressure which is right on average, or to constantly vary the fan speed to have a constant pressure maintained whether the user is inhaling (faster fan) or exhaling (slower fan).

If you do mean APAP, not CPAP, then the sensors you need to monitor will need to be much more sensitive, in order to determine if the user is snoring or holding their breath, requiring delivery of the higher pressure, or if they are breathing normally, requiring lower pressures. this of course would require monitoring of the sensors, interpretation of the results and development of an appropriate algorithm to determine what pressure should be delivered in what circumstances.

Any solution would need appropriate safety features to prevent it from delivering a potentially harmful surge in pressure, to ensure the motors don't overheat in several hours of continuous use, filtrating for the air passing through the device

It would not be possible to use any home spun device to be used to monitor compliance for the DVLA, or you healthcare provider.

If any of the engineering above has you confused, don't do it, but basically, don't do it anyway! Your health is much more important than that.

[mintra]

Good and useful answer

In practice I have a really good machine already, and I would not look to self treat.

As someone how was exhausted all my life without knowing it, one learns never to do something for one reason.

My friend said on Saturday that he can not play his guitar and his accordion at the same time, so I said I would do the bit that make the air blow, this also needs to be variable and have similar pressures to my apap machine.

So I think I will use your advice to make that first, the worst I can do is then make a really bad noise.

Thanks

[Fredxx]

In that case, I would advise going with the radial fan to produce the blow, and build a foot pedal with a rheostat (variable resistor) to control the fan power to give the variation that it needs. the power regulator becomes less of an issue, because you would want to be constantly adjusting the air pressure to power the accordion.

Of course, that does mean that the accordion is basically an air powered organ...

And don't both those instruments need two hands to play anyway...guitar has one to form the chords and the other to pluck the strings, and the accordion has one hand playing the chord buttons and teh other the keys...

[Richard]

From your description, Fred, that has all the makings of a Dyson vacuum-cleaner. And, as I understand it, James Dyson built over 500 prototypes over 20 years before he got it right.

Apart from having the creative/engineering ability, there's also a hefty amount of determination involved to see it through.

Richard

[James @ Intus]

Yeah, build it fan-less, like the new Dyson bladeless ventilators. That would be cool.

We had a customer who built a CPAP himself once. I did encourage him to share the details here but don't think he got around to it. It looked very interesting, though can't remember whether it was a success, as in, on par or better than anything available now.

[Fredxx]

From your description, Fred, that has all the makings of a Dyson vacuum-cleaner...

If I wake up with my Dyson vacuum cleaner trying to suck the air from my lungs, I'm sending it back!

I have to admit, I did write it being deliberately scary on teh engineering side, as it probably isn't something you should even think of trying unles you understand the principles properly.

The first description is pretty much how my first F&P machine operated - no clever monitoring, and had to be checked and calibrated regularly by the clinic connecting it to a pressure gauge and fiddling with an adjusting screw - not exactly high tech! The more clever monitoring came to the F&P machines by the time I got my second one, 6-7 years ago.

As for APAP - a much more complicated project! Although I have to admit I would relish the challenge of applying neural networks and Baysian regression to develop the fuzzy logic algorithms to deliver effective APAP therapy...and I am guessing that is a more detailed and advanced method than many manufacturers would use

[symmit]

a thought

I wonder if there'll be a manufacturer brave enough to make an apap / auto bipap for the self-treating self-controlling therapy community? It could be a best seller, we could all contribute ideas to its development and features and best of all it could be designed to help us adjust to our own needs!

[Berneta]

Key words

I think the key words I just read are, "If I wake up." Why go to all that trouble when you can get a Cpap or Apap, that is already made, and made safe? Good Luck x Berneta

[mintra]

I can think of one good reason

Price is a good reason, this leads to hospitals drawing the line for provision on the basis of cost.

The first test is some paper based form, I very nearly did not get put forward, My father who is 85 has just been told that he does not have sleep apnea, however I can spot another zombie a mile off.

He has been exhusted all his life just like me.

If the market was flooded with really good cheap machines, that worked then people would find that they help for all sorts of other things.

I am certain that if someone is miss diagnosed and treated in error it does not harm, what harm is cpap treatment to someone who does not need it, they wake up feeling just the same, and would not use it.

Anyway I have just got may hands on a machine which is nearly as good as my autoset spirit 2, a dimension 1200es.

I will make the organ blower first.

[Berneta]

Alls well that ends well

I guess if you make your own machine and don't feel any better or worse then all would be well. But if you need one and it doesn't work properly--you could end up not breathing. Cost is a big factor with Medical Supplies everywhere. I hope you can get a good one somewhere without paying a fortune for it. If you don't get checked out at a clinic--you will need advice on how to set the machine yourself. Good Luck.x Berneta