Philip Newton (pne) wrote,
Philip Newton

Sleep lab: my second night with CPAP

This night, I made sure to tighten the mask a bit more than the previous night, and that paid off: there was only a small whistle at once point and a slight movement made that go away, too.

On the whole, the night was less eventful and quite a bit more restful than the last.

I woke up a few times, but quickly fell sleep again, except for twice.

The first time, I had the feeling that my nose was so congested that I couldn’t get enough air; I had the feeling that my diaphragm had to work hard to build up negative pressure and even so, the flow of air wasn’t as much as I wanted. It felt like drawing up a syringe: at first, you can get the liquid to flow in faster by pulling out the end faster, but after a while, the diameter of the needle will put an upper limit to the volume you can draw in per unit of time.

So I called for the nurse and described my problem and asked whether they could increase the pressure, in the hope that that might help. She said that the pressure should be adjusted automatically, but increased it one notch (however much that is; perhaps 1 mbar/1 cm H2O?) anyway. I didn’t feel a difference; breathing still felt laboured if I wanted to get as much in as I wanted, and I thought that as hard as I was working to get enough air, I wouldn’t be able to fall asleep.

But then I figured that they were measuring my blood oxygen saturation, so if I really wasn’t breathing enough they’d notice and take appropriate measures; it’s not as if they were going to let me suffocate. Then I calmed down a bit and my breathing seemed to be a tad easier, and I fell asleep again after a bit.

The second time, there was water in the air hose; this night, they had turned on the humidifier, and apparently it had been set too high. When the nurse took the hose off the mask to check, quite a bit of water came out onto the pillow and the floor, so she took it off the machine as well and came back a short time later to fit it again. I also took off the mask and dried my face (my nose had gotten a bit wet, too, as had the inside of the mask), then I went back to sleep; things seemed to be fine after that.

The morning was the usual procedure: taking the mask as well as all the wires off at some ungodly hour, then sleep a bit more until quarter past seven. Breakfast, read a bit, then the doctor came by and discussed the night and the future.

Apparently, last night I had only gone up to 7 mbar (as opposed to 8 the previous night), and that’s what the machine I would be prescribed would be set to. Apparently, I had also had central apnœa a couple of times the first night (where the brain “forgot” to breathe, rather than an obstruction somewhere preventing me from breathing), which she said she’d use as an excuse to get me tested again there in six months—usually, they like to check up on patients themselves, but the normal procedure is for later checks to go through the pulmonologist. However, the good news is that central apnœa tends to go away once CPAP therapy has started.

We discussed device types as well. I asked whether I’d get a BIPAP machine (with different pressure for inhaling and exhaling), and she said those are usually only indicated for people who need higher pressures. And APAP (which automatically varies the pressure) is typically only for people whose breathing difficulties vary depending on things such as their position (e.g. who only have problems while they’re lying on their back, or only on their left side, or whatever). So I’d be getting a plain-Jane CPAP machine with constant pressure. However, I would probably get one with exhalation help, where the pressure is reduced a bit once you start exhaling so you don’t have to exhale against such a strong resistance; I believe that the device I used during my stay there also had this. (I have no idea what the difference is between this “flex” feature on a CPAP machine and a BIPAP machine, since both seem to involve a difference in pressure during exhaling.)

Then the doctor left, and a bit later, the nurse came around again with a document saying I had been in hospital for in-patient treatment from the 28th to the 30th (which I intend to hand in to my employer) and a return appointment, then I was free to go.

Unfortunately, that was just a few minutes too late for me to catch the bus which goes from the hospital straight to my home, and I didn’t feel like waiting for 40 minutes (well, about 30 at this point) for the next one, so I went to the bus stop to catch the other bus (which goes much more frequently but where I’d have to change). Then I realised that I could walk a couple of blocks further and reach a bus stop for my route, so I did that, and caught a bus home from there.

So now, waiting for the machine to come. (Apparently, the mask will come in the post, and the machine will be delivered by a technician from the manufacturer who will also intruduce me to it and instruct me in its use.)

And also: based on some material I read that they had provided in the room, it may be illegal for me to drive right now (people who have diagnosed sleep apnœa which is not currently being treated). Ah well; that would only be for a couple of weeks and I rarely drive anyway.

Tags: cpap
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