Modding the Resmed S8 CPAP Machine

Finally, after several overnight studies in two different sleep labs, my doctors have prescribed me a C-PAP machine. Basically, it's a bed snorkel. The mask provides pressurized air to your airways while you sleep, reducing the number of times your airways collapse and try to choke you. Now, if you just died in the middle of the night, this wouldn't be so bad. I mean, it's just death, but what actually happens is that your brain, for some odd reason, realizes you are choking, and wakes you up, so you semi-consciously start breathing again. If this happens frequently enough, instead of dying peacefully in your sleep, you wake up feeling like sleeping is very hard work. In other words, barely rested.

So, enter the CPAP machine. Keep your airways full of air, and you don't wake up before choking to death. In fact, you don't choke much at all. No dying, no waking. Just nice even sleep.

The one major problem I see with almost all CPAP machines being sold today, and the Resmed in particular, is that they really are not designed to be all that quiet, but more importantly for allergy sufferers, the filtration really stinks. They fit this tiny bit of polyester fluff in at the entrance of the machine, which basically won't filter out anything but big tufts of cat hair. Everything else in your room, you will breathe, at high pressure. Not a great way to spend the night. They do make in-line filters, but these have a chance of tricking the pressure meters into thinkign your air pressure is higher than it is. It really would have been oh so very easy for Resmed to put in a HEPA filter on the inake.

I should have taken a picture of the intake before I cleaned it for you to see. It was really dirty. Also, instead of providing you with a place to put an intake filter, or at least a place to attach one to, Remsed instead has an opening that makes it almost impossible to attach anything useful to the intake, like for instance, a muffler, or a HEPA filter. Very frustrating. And on top of everything else, my MD prescribed this particular model. Mind you, it works very well, and I understand it's very reliable, and small and portable and the integrated humidifier is pretty sweet, but they are like morticians. They really don't want you shopping around for the best casket, they want you to buy the one they tell you to buy.

So, what is a hacker like me to do? Well, it turns out that in the woodworking and industrial worlds they make these huge dust collection/air cleaning systems. Often a professional mill work or woodworking shop, and sometimes advanced hobbyists, will have large dust collectors with 4-6" ducts running around their shop, sucking up all the wood chips and keeping the shop clean and the air breathable as the craftspeople work. The air gets expelled in a variety of ways, including through these long polyester felt tubes, at the bottom of which is usually a trash bin of some sort. Anyway, the point is, the polyester felt used in these bags normally filters materials down to 1 micron, and after getting nice and packed with wood dust, they get even better, filtering down to 0.3 microns, or about. Not quite HEPA standards (0.3 microns all the time) but MUCH better than what Resmed provides.

So, my solution? Purchase a bag from Oneida Air , cut out just enough filter media to cover the intake, duct tape it in place, and voila, suddenly I can breathe easier at night. :) I've tried it at least one night, and it worked fine, with no apparent change in performance of the CPAP machine. If I was really clever, what I would do is measure the amperage while it runs to see if there's a difference in strain on the air pump with and without the felt, bur right now, my work and school are taking up too much of my time. If I had more time I would have created a felt "pocket" so that I could increase the surface area of the filter. In the next incarnation this is probably what I will do, though honestly it's hard to tell it needs it.