Seeking Advice on Reducing Flow Limitation in CPAP Therapy

[iamhero]

The sleep study I (male, 31 years old) took showed that I have an AHI of 15, so I started CPAP therapy two months ago with a fixed pressure of 10. My AHI has since decreased to around 3, but I have been experiencing nausea. Additionally, my flow limitation has been above 0.1 on most days, sometimes reaching 0.4.

Some days, I still experience brain fog and fatigue. I have tried different setups, including using fixed pressures of 7 and 8 with EPR enabled, as well as APAP pressure settings between 6-11, both with and without EPR set to 2 or 3. In all cases, my AHI remained under 4, but my flow limitation was inconsistent. About 50% of the time, it stays under 0.1, while at other times, it rises above that level, fluctuating unpredictably.

I checked my oxygen levels, and they are usually good, staying above 90% most of the time, typically above 95%, though occasionally dipping to 89% or between 90-95% for brief moments.

I am unsure of what to do next. I have noticed that on the days when my flow limitation stays under 0.1, I feel better, but despite trying different settings, my results have remained the same. Below, I have provided some instances of my results.

Could you please provide your suggestions on how to reduce my flow limitation?

https://sleephq.com/public/3ac0aef0-2d1 ... 90e6e619ec
https://sleephq.com/public/dc10e7b5-be7 ... b1e98b7f18
https://sleephq.com/public/802da7d8-8d3 ... ef236ada2d
https://sleephq.com/public/de758717-730 ... a18002347f
https://sleephq.com/public/3a69d95c-5ab ... feded44560

[mlmollenkamp]

Is your machine strictly a CPAP or does it have an automatic (APAP) mode? I'm surprised you would be prescribed a non auto CPAP these days.

It appears that the pressure is too low, I'm extremely uncomfortable with pressure below 9 CM. I don't think most people with obstructive apnea's get relief with pressure that low. I would go back to the prescribed 10 CM pressure for a few days. If you are still having obstructive events increase it a little at a time to reduce them. Start at 10 for a couple of nights, then 10.1 or 10.2.... Continue to increase pressure until the obstructive apneas are controlled. Its not unusual to need quite a lot more than 10 for obstructive apnea. Ideally you should be able to get the obstructive apneas down to 1 or so.

It looks like some nights you have a significant number of central apneas as well, I have complex apnea so my central apneas dominate. For most people the central apneas go away after a few weeks. But its possible the central apneas may increase when you increase pressure. If so increase the pressure until you more or less equalize the number of central and obstructive events. On your SleepHQ charts they are called OA and CA. The H events are hypopneas, they can be either central or obstructive so ignore them initially until you find the pressure that clears the OA's. Your AHI's are similar to mine, not so high a doctor will be terribly concerned, but high enough to have fatigue issues. I have issues with an AHI of 2.5 or above. You may feel tired for a while even after things are working well, it sometimes takes a while to notice improvements, just go slow so and give things time to work. I try to make small adjustments, then live with them for a few days before I change anything else. Its necessary to average over a few days to know if a change is beneficial.

You didn't say what machine you have. If it has an APAP mode you would be better off using it. Set the minimum for something like 7 or 8, and the maximum to 13 or so. Use the machine for a few days to see what it does. You probably don't have to do anything else. Turn on ramp if it feels like too much pressure to fall asleep.

You can turn on EPR if you feel like its too difficult to exhale, but if you don't have to use it if you are comfortable. Start with EPR during ramp so it's not on after you are fully asleep. Both ramp and EPR are mostly there for comfort, no need to be concerned with them unless you are uncomfortable. I don't use either ramp or EPR. The Ramp and EPR recommendations apply to CPAP as APAP. Initially they are a comfort matter and don't usually change the effectiveness of the treatment unless you are uncomfortable.

Finally try to see if your sleeping position is affecting your apneas. I have a lot more obstructive apneas and leakage when my chin slumps down. I wear a cervical collar for that, it cut my AHI down from 4 to about 2.5. I also have a tremendous number of central apneas if I sleep on my right side. Sounds strange, but sleeping position matters quite a lot, at least for me.

Let us know what machine you have and how things work out.

[ozij]

Is your machine strictly a CPAP or does it have an automatic (APAP) mode? I'm surprised you would be prescribed a non auto CPAP these days.

The information is clearly there in the SleepHQ links supplied by the OP.

[ozij]

On this chart
https://sleephq.com/public/3ac0aef0-2d1 ... 90e6e619ec
your leak rate is unacceptably high.


On these two charts, with a constant pressure of 9, your flow limitations are accompanied by additional indication of obstruction, namely snores, obstructive apneas, hypopneas and a generally lower flow rate. Your machine can do nothing to respond to them, since you've limited it to a pressure of 9.
https://sleephq.com/public/dc10e7b5-be7 ... b1e98b7f18
https://sleephq.com/public/3ac0aef0-2d1 ... 90e6e619ec

On this chart
https://sleephq.com/public/de758717-730 ... a18002347f
your pressure is even lower, and once again, flow limitations are accompanied by snores, and the whole mess seem start just about when one would expect the begining of REM sleep. Some people have worse obstructions in REM and can benefit from a varied pressure.

The fifth link is "not found".

Based on the four charts that are visible I'd do the following:
Set the machine up in Auto mode, not CPAP.
I'd start with a minimum of 7 and a maximum of 10.
My aim would be to let the machine find a maximum pressure at which I don't snore.
I'm thinking of a minimum of 7 because you did have a period of what looks like restful sleep on that pressure.

Once you make the change, stick to it for a week or so before making further changes.