Sierra

On the A10 ResMed the SD card is on the left hand side behind a flexible door you pry up. They typically come with a 4 GB SD card from the factory, but for some reason (possibly not honorable) some dealers remove the card. The card is the only place all the detailed data is stored. If it came with one, all the data should be still there for you to download with OSCAR. If not, you can put in a SD card from 4 GB up to 32 GB. No real advantage in more than 4 GB, so you may have one laying around from a camera or some other device where it is no longer needed.

The data that gets sent over the air by the machine is very limited summary data, and is mainly used for compliance purposes that some are obligated to provide.

Are you using OSCAR to track your results? It can be very helpful in determining what is happening during the sleep.

On a ResMed, make sure the EPR is set at 3 cm, and on a DreamStation the same with the Flex.

One of the best ways to make exhale easier is to increase the EPR (expiry pressure relief) to 3 cm. This reduces pressure on exhale only. Higher pressure on inhale is helpful to make breathing easier. On the DreamStation machines I believe this is called Flex. On the ResMed machines it is good to use the Auto for ramp time, and make sure the ramp start pressure is high enough.

It does take some time to get used to sleeping with a CPAP, and can be a bit annoying until you settle into it.

I am a bit pressed for time today but here is my quick response. Yes, higher than necessary pressure can cause CA events. In a nutshell what I have done is switch from Auto to fixed pressure CPAP mode. I then have experimented with lower and lower pressures trying to find a point where CA events are minimized without causing OA events to rise significantly. In my case that has turned out to be 11 cm. I have also set my EPR to 3 cm full time and that seems to minimize hypopnea events.

I forgot to answer your question about how the CPAP machine detects the difference between CA and OA events. When flow stops it starts to oscillate the speed of the fan. It then watches to see what happens to the pressure. If the pressure does not oscillate with the fan speed or does not oscillate significantly then it determines the airway is open and classes it as an CA event. It holds the pressure the same and does not increase it. And if the pressure does oscillate with the fan speed it determines the airway is obstructed, and then will increase pressure to try and clear it. If the flow stop for 10 seconds or more it gets recorded as an event. If less than 10 seconds it is not recorded. If you zoom in the scale with OSCAR you can see the machine doing this activity. If the machine cannot distinguish between CA and OA, usually when mask leakage is high, then it records it as an unidentified event. Hypopneas are flow restrictions without a complete loss of flow and are determined just based on flow.

You are correct in that the CPAP machine can report irregular breathing while you are still awake as apnea events. When going to sleep the ResMed machines minimize this effect by not counting any events until the ramp period is over. The newest machines when the ramp is set to Auto for time will detect when you go to sleep and end the ramp time. But, as you suspect when you are waking up this feature is not in effect and that period of time can increase the apnea count. About the only good way to get a handle on that is to use a freeware program called OSCAR which can read the data from the SD card on your machine and produce graphs of your whole night's sleep so you can see when apnea events occur.

Some call these false apnea events "Sleep Wake Junk", and disregard them. However, it is quite possible to have real central apnea (clear airway) events while obstructive events are low. Central and obstructive events are very different. Obstructive events are more common and can be reduced or eliminated by pressure from the CPAP to open the airway. Central events on the other hand occur with the airway open and more pressure is of no value. The better machines like the ResMed do not increase pressure in response to central apnea events. Central apnea events can be caused by many things, but the root element is the body deciding not to breathe. In most cases this is caused by a CO2 and Oxygen imbalance that is not stable. You have too much air, then too little, but the body has trouble bringing the balance under control. This is something you can see with OSCAR graphs.

If you download OSCAR you can post the graphs here for comments on what might be going on. You need a PC or Mac, and an SD card reader. I struggle with this issue and on average my CA events are about double the OA events. I have tweaked things with my CPAP and pretty much gotten it under control with my total AHI averaging currently at 0.82. But it takes time, and is not always successful. Here is a link to an article on potential causes. When you are on CPAP the first suspect is the CPAP itself. Using higher than require treatment pressure can cause CA events to go up.

https://www.mayoclinic.org/diseases-conditions/central-sleep-apnea/symptoms-causes/syc-20352109

These are the ones we got off Amazon. They are quite fine, but Amazon offers lots of choices, so there may be better ones. They collect dust faster than the coarse ResMed versions, and I replace them every 4 months. We were letting the ResMed ones go much longer than that, and that now appears to have been a mistake.

https://www.amazon.ca/gp/product/B07Z953DQG/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

I see we bought them in November 2021, so we have been using them for a while now...

I think now, that the real secret to preventing this issue, may be to do a "big blow out purge" each time you replace the filter by turning the Mask Test feature on with the inlet filter out and the mask disconnected from the machine. that would ensure the highest possible air flow with no risk of blowing debris into the mask vent.

It certainly was unexpected. I never considered that dust/dirt could have been building up in my machine and then come out all of a sudden. That is why I thought I would post it, so others could be aware of it. Had another good sleep last night. I even went over the leak red line, so it seems the vent is now functioning normally again.

I had a rather unusual experience with my ResMed AirSense 10 machine and ResMed AirFit P10 nasal mask recently. I thought I would post it in case someone else encounters something like this (or wants to avoid it happening). On Thursday last week I had a quite normal sleep. CA events were a little high, but other than that, normal. Here is the OSCAR daily report. Notice the leakage graph in particular which shows peaks of leakage but none going over the red line. Also look at the Minute ventilation. It starts out elevated at about 15 but quickly settles down. This is all normal for me.

The next night I had trouble getting to sleep and couldn't seem to "get my breath". I did get to sleep fairly quickly though. But there were some unusual graphs. The Leak Rate basically went to zero. I have never seen that before. And Minute Ventilation started out high at 24, but settled down. See this report.

The two nights after that were just as bad or worse. Minute ventilation when going to sleep was as high as 30. I was really struggling to get my breath. The Leak Rate was still reporting essentially zero. And, I noticed that my humidifier water consumption had gone down to about 25% of what it normally is. I presume when there is less leakage there is less water consumption. I increased my Ramp Start pressure from my normal 9 cm, to 11 cm, but that did not help. I was attributing it to the hot weather, but I finally concluded something was wrong with my mask. So I gave it a thorough cleaning. The very fine screen vents on the P10 actually looked black. I have never seen that before. I used vinegar and Dawn soap which is my normal method of cleaning, but the vents did not seem to clean up. I finally used a toothbrush dipping it in isopropyl alcohol, and blowing it from the outside to inside direction with a small portable air compressor. That seemed to work. Here is my results from last night after the cleaning.

Success! Minute Ventilation has returned to normal and the leak rate has returned to normal. And I had a comfortable sleep with no gasping for air. CA events were a bit high, but that happen for me from time to time.

So what caused it all? I guess I could say that we have been having lots of forest fire smoke recently and blame it on climate change. But, I don't really think so. When I think back, I had an oops event on the Thursday before this all started. Instead of turning on the prewarm before going to bed, I accidentally turned on the Mast Fit Test. I recall there was a big rush of air as I did not have the mask on. I kind of think what happened was that the rush of air blew accumulated dust/dirt within the machine into the mask vents. The CPAP inlet filter which is a very fine after market type was clean, so I have to think the dirt came from within the machine and was dislodged by the high flow rate of the mask test. I have been using fine inlet filters for about a year now, but before that I was using quite coarse ResMed filters. I suspect over time they were allowing dust/dirt to accumulate within the machine. I have now done the mask test a few times with the mask and hose removed in hope it would blow out any more dirt inside the machine. It will blow for a short time and then shut down reporting the mask leakage is too high.

I guess we will see if this fix cures the problem. It has worked for one night! Lessons learned?

1. At least for this P10 mask be suspicious if your leak rate drops to zero or near zero
2. Use a fine aftermarket filter on the machine instead of the coarse ResMed ones
3. Periodically run the Mask Leak test with no mask in place to blow out accumulated dirt in the machine.
4. When cleaning the P10 very thoroughly clean the fine mesh vents, and if necessary use isopropyl alcohol and air.
5. And last perhaps there are reasons to replace the whole mask. This portion of my mask is the original and is coming up to 5 years old! I probably should get a new one ($120), but this cleaning job seems to have worked, and I now know what to look for...