Sierra

With all those extra red blood cells have you considered taking up marathon running or long distance biking? Seems to me that those guys do all sorts of devious things to get their blood cell count up. You could do it legally!

I'm guessing a bit without being able to see the SleepyHead graphs but I think what you found out is that a minimum of 8 cm and maximum of 12 cm is too much pressure for you and caused your excessive central apnea events. This is kind of validated by the better results you got at 6 min and 10 max. And of those pressures the Max pressure is the critical one. It would seem you avoid centrals if pressure is under 10, but you get them when it is between 10 and 12.

I agree with the pulmonologist in that the EPR is better left off during the treatment period of the sleep. The reason is that your pressure is cycling up and down with each breath. If your obstructive apnea is occurring during the exhale the effective pressure preventing obstruction is for example only 7 cm when your inhale pressure is 10 cm. The problem with that is that you are getting an effective pressure of 7 cm to prevent obstructive events, while enduring a 10 cm pressure which may be causing central events. My conclusion has been that EPR of 3 is fine during the ramp, but can hurt you during treatment the rest of the night. In the extreme for example a 10 cm inhale with 7 cm exhale may be no better than a fixed pressure of 7 cm for preventing OA events. And, obviously 7 cm is better for avoiding CA events.

The trick with the ramp is to use the Auto Ramp feature. I find it works very well, and limits the ramp portion to the period of time you are awake. You do not have to guess how long it will take to fall asleep. And the second part of the Auto Ramp is to set the Ramp Start pressure high enough. So say for example you want to use a 6 cm min and 10 cm max. You set the EPR to Ramp Only with a start pressure equal to your minimum of 6 cm. Then while you are awake pressure will cycle from 6 cm inhale down to 4 cm exhale. When you fall asleep the EPR will stop and your inhale and exhale will be equal. You will have no reduction on exhale to make the treatment less effective. And, if it works well your machine will not have to increase pressure as much. The net result can be a significant reduction in actual pressure.

This all said another issue can be hypopnea events which are potentially central in nature can drive up the pressure. The only fix that I have found for that is to lower max pressure to prevent it, or in the extreme just switch to a fixed pressure. Remember the bottom line is that you want to limit pressure to as low as possible to prevent CA events, without having it so low that OA events start to spike up.

Generally apnea events which occur when you are awake are false flags. You won't get those false flags when using the Auto Ramp feature as the machine is smart enough to suppress those false flags until you actually fall asleep.

As far as needing different pressures at altitude I found one study that concluded with obstructive apnea there was no need to change pressure. That makes sense. The central apnea is a bit different matter. Your pressure needs for preventing OA should stay the same. The maximum pressure you can tolerate without excessive CA may be lower at altitude. That means the tradeoff pressure point might be different. I'm sure you will figure that out with some experience and with using SleepyHead.

Here is the conclusion of that study:

"For obstructive sleep apnea patients living at altitude, changes in elevation between 10,100 ft (3075 m) and sea level do not significantly alter absolute CPAP pressure requirements."

I take a bit of exception with the use of the word "absolute" because the machine does not use absolute pressure. I think they could have said it more accurately by simply saying you don't need to adjust the machine pressure setting for different elevations.

Edit: As for pressure settings, I think you might be better off with a minimum of 7 cm unless it causes centrals. It will give you more air while getting to sleep. It will let you move the ramp start up to 7 cm. I currently use a Ramp Start pressure of 9 cm for that reason. But, I run a fixed 11 cm, so I can start higher.

There are different types of nasal pillow masks. I use the ResMed AirFit P10. It has a couple of double layer cone shaped pieces that fit into your nostrils. My wife uses a F&P Brevida. It also fits into each nostril but also fits around the nose a bit. DreamWear has two types of inserts that can be used with the same frame and headgear. I have not tried them, but others report they are good. One insert kind of fits under the nose and has a single wide oval opening in it. They call that the nasal version. The other is a more conventional nasal pillow prong type with gel cushions.

The P10 is probably the least expensive of the choices and the most popular. The main drawback is that the headgear is flimsy. But, if you use a chin strap and put the mask on first, and the chinstrap second, that keeps it in place. I use the Breathewear Halo chin strap with the P10, but I still get mouth leaks, so I tape my mouth too.

What CPAP machine are you using? The ResMed and DreamStation machines have an optional heated hose. When used at least the ResMed can be set in Auto for humidity. I find that quite comfortable and does not dry my nose out. I suspect the DreamStation does the same, but I am less familiar with it.

Did a little more research on this subject, and yes older machines did have an adjustment for altitude. I have not found a good reference for it yet, but here is what I have concluded so far.

The machines use gauge pressure so kind of by default they adjust automatically for altitude. However the problem is that these machines measure pressure in the machine, not at the mask. There is always a pressure drop due to flow resistance from the machine to the mask. And of course to prevent obstructive apnea it is the mask pressure that counts. For that reason the machine smarts estimate this pressure drop and use it to in turn estimate the actual mask pressure. Machines may have a setting for different hose sizes that is used to make this estimation more accurate. Larger diameter and shorter hoses have less pressure drop. The impact of altitude due to the thinner air is an increase in the pressure drop which impacts the accuracy of the estimated mask pressure. In the older machines you could correct to some degree for this by manually inputting an altitude or range of altitudes. Now it appears the modern machines may be measuring absolute pressure in addition to the gauge pressure. The absolute pressure then is used to make a better correction of pressure drop in the hose. I have not found a source that definitively says this, probably because manufacturers guard their technology for competition purposes.

In any case if the new machines are doing this I have to give them more credit than I have been. They may actually be automatically correcting for altitude pressure drop using a absolute pressure measurement (barometer). Will have to do some digging. About all I have seen from ResMed is that their new machines correct automatically but some of their portable machines may not. Perhaps it is an issue to fit the absolute pressure transducer in the small machines. That is a bit odd, because for those who want to use a CPAP on an airplane, the cabin pressure is maintained to the equivalent of about 7,000 feet.

I am not aware of an altitude setting on the S9 or the A10. What they do claim is that the machine automatically adjusts for altitude change. I think that is kind of like saying the wheels on our cars are round. CPAPs measure pressure in cm of water relative to the atmosphere - commonly called gauge pressure. So if your machine is set at 12 cm of pressure at sea level, that is relative to sea level atmospheric pressure. At 7000 feet it is the same. The machine will deliver 12 cm of pressure relative to the atmospheric pressure at 7000 feet. The machine maintains the same differential pressure which is what counts. The absolute pressure will change, but the gauge remains the same. To my knowledge all machines do it up to a point. When the air gets too thin (elevation too high) you can get to a point where the fan in the machine cannot pump enough air to maintain the pressure. So what you will find is that each machine will have a specification as to the maximum elevation it is good up to. For the S9 it is:

• Operating altitude Sea level to 8,500’ (2,591 m)

The key point is that while the gauge pressure remains the same at altitude, the oxygen content goes down as the air gets thinner. For those susceptible to central apnea that lower oxygen content can make the breathing regulation system more unstable, and cause additional central apnea events. To my knowledge the machine does not compensate for that factor.

Here is a link to the S9 technical manual, but on a quick read all I see in it is the maximum elevation number.

S9 Tech Manual

Your two elevation work and living arrangements may provide a bit of a challenge to get your machine optimized. It may be that you will have to use two different pressure settings; one for sea level, and one for the 7200 feet. I think with complex or mixed apnea the pressure settings are almost always a compromise as they can go in opposite directions with increasing treatment pressure. The compromise pressure may be different at sea level compared to at elevation. One would think in Auto that the machine would be smart enough to automatically compensate. However, it is just my personal theory, but I feel at least in my case, my machine chases hypopnea with pressure increases. That is fine if the hypopnea is obstructive. But if it is central it makes things worse. For that reason the machine may not work that well in auto mode.

I found this blog article at this website quite informative on the subject of complex sleep apnea. He mentions the use of acetazolamide to treat central sleep apnea. Apparently it is used to treat altitude sickness and is off label in treating central apnea, but there is some indication it works. It is a diuretic like some blood pressure meds. I have thought about asking my doctor to switch the beta blocker for the acetazolamide. But, my research indicates it is probably off label to treat blood pressure too, so it would be asking him for a lot. I've put that idea on the back burner now that with a lower fixed pressure I've gotten my AHI down to what I consider an acceptable value. For December my central index was 0.45, obstructive 0.34, and hypopnea 0.79. I suspect about half the hypopnea is central apnea related. If that continues, I'm OK with that.

Another thing to watch for is Cheyne Stokes Respiration. Your machine and SleepyHead will flag it if it is an issue. I have been seeing a bit of it about once a month. However over the last 3 months or so the frequency seems to have dropped. I have not had it since I went on the fixed 11 cm CPAP mode over a month ago. I'm hoping the lower pressure addresses that too.

If you don't have it already here is a link to the clinical manual for your machine. It is good to keep as a reference. Some good info in it on how the machine works.

Technical Manual

I also have Type 2, hypertension, obesity and was diagnosed with a 37 AHI sleep apnea. My red blood cell count, and hemoglobin always comes back just under the lower normal limit. I don't have hypothyroidism, or high triglycerides. I take Crestor to get my LDL under the limit for Type 2's. I might meet LDL normal limits without a statin. My Type 2 is well controlled with metformin and insulin. And my hypertension is also well controlled with meds. I've been on the CPAP for about 9 months now. I can't say I have seen any significant differences in my blood test results which I get done every 6 months (last about 3 months ago). When I was diagnosed the sleep tech tried to tell me that a CPAP would cure my diabetes. I told her that I thought that was total hogwash! My insulin requirements have not changed at all under CPAP treatment.

On the sleep test results, while I think it is possible (but difficult) hypopneas are not usually classified as obstructive or central. The central portion of my diagnosed AHI was very low. However with CPAP treatment it emerged as an issue. During my trial period on the CPAP I think I averaged about 4 AHI with most of it central. This sounds fairly similar to your situation. Over the last 9 months I have tried a lot of different settings (about 30 or so) with my AirSense AutoSet machine, and I now have my AHI on the latest trial under 2. Everyone is probably different, but the secret for me has been a switch from Auto mode to fixed CPAP pressure mode.

If you want to post some SleepyHead Daily report screen shots I can give you my thoughts on where your opportunities may lie for improvement. SleepyHead is free to download software that displays your sleep data from the SD card in your machine. You need a PC or Mac and a SD card reader. All your data since you got the machine should be on the card. Do you plan to adjust your own machine, or work through your sleep clinic?

I certainly would be interested in knowing how your results change at altitude compared to sea level. I have had a theory that higher elevation makes the frequency of centrals worse. We recently spent 2 weeks at sea level compared to our normal 2000 feet at home. There seemed to be a small improvement at sea level, but not sure it really statistically significant.

Hope that helps some. If you have any questions just ask.

Edit: Here is a link to the thread where I somewhat documented my journey to using fixed pressure CPAP mode. Oh, and after I thought about it a bit longer, I have made one change in my medication since starting CPAP. I did a trial and then convinced my GP to cut my beta blocker blood pressure dose in half. It seemed based on my trial that the lower dose reduced my central apnea frequency.

Yes, at -15C and a brisk north wind, it forces me get the parka with hood out.

This is the nasal mask insert:

This is the nasal pillow gel insert

I think sleep patterns are highly individualistic, and the impact of sleep apnea also highly variable. My wife was diagnosed with an AHI of 80+. She was having a hard time getting what she considers enough sleep. Now with CPAP she still likes to get more than 8 hours, but she does it with an AHI of less than 1 on average. She thinks that CPAP has made a tremendous improvement in her sleep. On the other hand I was diagnosed with an AHI of 37. I was having no problem with sleeping, but did snore a lot, and while I had some excessive sleepiness symptoms, they were not really that bad. I suffer from some central apnea and struggle to get AHI under 2. I would say my daytime sleepiness has been reduced by a modest amount. My current objectives are to limit my sleeping to under 8 hours. I think trying to sleep too much reduces sleep quality. In short apnea seems to affect different people differently. You will learn a lot when you get your sleep study results as to where you stand with it.