Sierra

I have had significant issues with CA events and occasional CSR flagging. It is a complex area and the combination of OA and CA events are called complex apnea. One of the better articles on the issue can be found here:

https://myapnea.org/blog/complex-sleep-apnea

I am also on a beta blocker (bisoprolol). I was convinced that it was contributing to my CA frequency and CSR and convinced my doctor to reduce my daily dose from 5 mg to 2.5 mg (I split a 5 mg). That seemed to help some. And over the past year or so, I have made some changes to my CPAP settings. I had my EPR set to ramp only and I switched it to full time and set it at 2 cm. That has had a large impact on my hypopnea frequency, and it seems it may have also reduced my CSR frequency. I still see the periodic repetition of the CA events, but very seldom do they get flagged as CSR any more. That is about the only changes I have made. And of course I have not gotten any younger! I'm pushing 74 now.

It may be worthwhile discussing it with a cardiologist to see if they can suggest anything. Not sure what you are taking for a beta blocker, but my doctor thinks bisoprolol is better than the more common metoprolol (at least for me). You may also want to discuss the dose. I am mainly taking it for BP control, and also use perindopril. The combination seems to work quite well for me, but everyone is different when it comes to BP issues...

I am convinced that CSR is a blood circulation issue. That in turn leads to an instability in the control system that keeps O2 and CO2 at a constant level. But, the details are complex.

As I understand it, the ResMed machine calculates mask pressure based on the pressure measured inside the machine, and considers the flow rate along with the size of hose that goes to the mask. It does not measure the actual mask pressure but calculates it based on pressure, flow, and pressure drop. This compares to the Pressure graph which just shows the pressure demanded. The Red shows IPAP and Green EPAP. The difference should be the EPR setting.

On the mask pressure graph you need to zoom in to the highest level of detail after clicking on a time of interest. Zoom in with the arrow keys. Then you can move the cursor so it sits exactly at the peak of a pressure cycle. The digital display at the very left and above the graph will show the pressure at the cursor point. That will be the IPAP or at least approximately. Then when you move the cursor to the very minimum point it will be the EPAP. The differential will be approximately the EPR, but may not match exactly as the mask pressure is an actual measurement with calculations applied. As you can see it varies with every breath.

You can think of it this way. The Pressure is the desired pressure. The Mask Pressure is the actual pressure. DreamStation machines do not do this calculation and do not display a mask pressure. The ResMed machines are more informative as they give you the actual pressure through the whole breathing cycle.

Your biggest issue is the high leak rates. They should be under 24 L/min. When you go over that you get the grayed out areas. Also the machine does not report apnea events during those grayed out time where you are over 24 L/min. With no events your pressure decays down to minimum. The high leaks are giving you a false low apnea event frequency because the events are not being reported.

You might get some improvement by turning on EPR and setting it at 3 cm full time. But until you solve the leak problem the machine really cannot operate. It seems possible that you are displacing the mask off your nose while sleeping. One of the things I do is use a satin pillow case to let the mask slip easier over the pillow without it being pushed off my nose.

Unfortunately CA events are not effectively treated with air pressure because the airway is already open. There are special machines called ASVs which are made to force breathing when it does not happen naturally. You may need an ASV like the AirCurve 10 ASV. What you may want to do is zoom in some of those periods of time when you are having multiple CA events to see if they look anything like the flow graphs in that ASV document.

With an APAP AirSense 10 about all you can do is reduce pressure as much as possible without causing excessive OA events. It looks like you have already done that.

CA events sometimes can be caused by other cardiovascular issues or some medications. You could see a cardiologist if that may be an potential problem.

There are no real big differences between the SleepStation and the ResMed. I prefer the ResMed, but I am not sure it is significantly more effective. Both my wife and I have the ResMed AirSense 10 Auto. She has the For Her version. In Auto the ResMed I believe is slightly better as it does not drop the pressure so fast after it raises it. Makes for a more constant pressure during the night. And, the EPR may be slightly more effective than the Flex. But, again the differences are very minor.

Unfortunately I don't think these techs know much about the machines and how they work. They just put them in Auto with a very wide range and hope for the best. A new machine out of the box is set at 4 to 20.

It is too bad that you did not put your own SD card in the machine so you could collect the data. All you needed to do is delete the data from the SleepStation and then use the card. To put it back in the SleepStation just delete the data again. They would not know that you saved the data to Oscar. OSCAR is smart enough to combine the data from the two different machines, so you will not lose any data in OSCAR. I periodically delete the data on the SD card as it makes it more responsive for downloading.

After I wrote this I got to thinking that your CA event frequency may be related to your slow heart rate. I have the opposite issue. I had been taking 5 mg of bisoprolol (beta blocker) mainly for blood pressure reasons. However it reduces my heart rate, but no where near your low 30's. When I was having issues with lots of CA events I got to thinking that it may be due to poor circulation due to a lower heart rate. I asked my doctor if I could cut my dose in half. I now take 2.5 mg daily instead of 5 mg. I believe my CA frequency has gone down. My current long term average is an AHI of 0.75 with the CA portion being about 0.5. You may want to discuss with your doctor. Not sure if there is a drug that does the opposite to a beta blocker and speeds up the heart rate.

I sounds like you would provide competition to Björn Borg with your heart rate.

On pressure the normal response is for CA events to go down when pressure is reduced. Before you go for higher pressure I think I would go down first to see if there is a point where OA events become a problem. If you are like me CA events can be quite erratic. My CA events typically are double my OA events, but they vary a lot from night to night. It takes a long time to determine where they settle out.

Yes, in theory if you lower EPR by 1 cm that increases effective pressure by 1 cm. The issue however is that it only has this effect on the exhale part of the cycle. So it will depend on what part of the cycle is causing the OA events as to whether or not you benefit from this higher net pressure on exhale. My final resolution on it is that the proof is in the eating of the pudding. Try it and see what impact it has for you. This said I think I would try lower pressure first to see if there is a point where OA's start to increase.

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You could try this link for a Clinical Guide. As I say, I am not that familiar with the AirCurve 10 VAuto. Perhaps you could review the setup portion of the manual to see if there is anything amiss. But, I'm thinking it is perhaps defective. I recall they have a 2 or 3 year warranty?

https://www.oxystore.it/index.php?controller=attachment&id_attachment=37

That is very strange. To be clear are you talking about the period of time from 21:09 to 21:12? - This would seem like the mask was not on, but I am not sure. Don't know how else there could be no flow?

Or, the time starting just before 21:22? - Here there seems to be flow, but the IPAP pressure has dropped to 11 cm suddenly.

I am less familiar with the AirCurve machines, but my first thoughts are that the machine may be defective.