After being on CPAP for many years, suddenly my AHI numbers are varying quite a bit. After struggling resolve it with APAP I finally found some success reverting to straight CPAP. SleepyHead was showing that my obstructive apneas were quite low, below 1.0. The majority of the apneas were reported as central apneas. For a a few weeks total apneas were in the 5.0 range which I find acceptable, but then they would steadily creep up to the 10.0 range again. A slight pressure adjustment would return the number back down, only to see it creep up again. I have been having pain from some herniated discs in my back and I can see that the Sleepyhead data shows a spike before some tags of a central apnea. I am attributing these to back pain restlessness. I am scheduled for a diagnostic shot in my lower back to isolate effected nerve for future treatment. I am curious if anyone has had varying AHI's due to other unrelated health issues.
I suffer from complex apnea and am convinced the type of sleep one gets and perhaps in the atmospheric pressure due to elevation change or even weather events can help or aggravate my frequency of central apnea. I look at the average AHI more than the night to night AHI. My thought is to not worry about it much until I start to average over 5. Then I will start investigating the use of an AirCurve ASV machine.
In the meantime I have done a few things which I believe reduces the incidence of CA events:
So far that is about all that I have found effective. I have found that vacations at sea level are good for reducing CA events, but that is not a totally cheap and practical solution --- yet! I live at 2,000 feet and I think the lower atmospheric pressure is contributing cause of CA.
In your case if you are taking any strong medications for you back pain you may want to ask your doctor about them being a potential cause. I have read that opioid drugs in particular are bad actors when it comes to causing central apnea.
Hope that helps some,
Thanks for the input. I use a Dreamwear full face make and I suspect that occasionally I can drop my jaw below its' bottom. Would I not see a drop in mask pressure associated with the central apneas if this were the case? I find your suggestion regarding circulation interesting. I am on a very low dosage of Metropolol (25mg) which I believe lowers my heart rate and my diastolic pressure has also been on the low side recently. I would gladly trade a slight increase in my blood pressure for improved sleep. Looks like I have further investigation to do. Again thanks
Central apnea is more likely to be caused by a higher pressure, not a lower pressure. It is best to do everything you can to keep pressure as low as possible. Turning Flex off on a DreamStation or EPR right off on a ResMed when sleeping often can reduce required pressure by a couple of cm, for example.
My doctor prefers bisoprolol to metoprolol for a beta blocker. He says that it has a much more uniform effect during the 24 hours of the day instead of peaking in effect a few hours after taking it. Metoprolol is often taken twice a day to minimize the peaking effect. I was initially prescribed 5 mg of bisoprolol to be taken once a day. I still split the pill and took half a pill twice a day. Then I did a bit of a test and stopped taking the evening half of the pill. It seemed to reduce the CA frequency and did not significantly increase my BP, or pulse rate. I also take 8 mg of perindopril, an ACE inhibitor, daily for BP. My doctor agreed to the change, so now I only take 2.5 mg of the bisoprolol once a day first thing in the morning. My thinking is that any peak it may have will be during the day, and not at night when I am sleeping and susceptible to CA events. I exercise at a gym in the late morning and can see the impact bisoprolol has on my heart rate if I forget to take it. Even at 2.5 mg a day it does limit heart rate during exercise.
You may find this article on complex sleep apnea of interest.
It is a good idea to have a titration study performed every few years. As we grow older and our bodies change, so can the type of therapy we require. Changes in weight, certain medications, and our overall health can all have an effect on our breathing during sleep. Disturbances in sleep can result in a higher number of central apneas. After an arousal, it is common for a person to experience a central apnea as they are going back to sleep. Are you on pain medication for herniated disks? Pain meds, especially opiods, can cause a decreased respiratory drive.
The type of mask interface you are using can also play a part. As a technologist in a sleep lab, I generally try to get patients to use full face masks, especially if they will be on higher pressure settings. The reason being is that at higher settings, the air going in through the nose will tend to exit out of the patient's mouth. This can result in sleep disturbances, as well as the person waking with dry mouth. I am not saying this happens with everyone, but I have seen this to be true for many patients. If you were on APAP, your sleep may have been disturbed as the pressure increased. The pressure will only increase if the device senses a blockage occurring. Therefore, if you changed back to CPAP at a suboptimal setting, you may experience more obstructive events in your sleep that the device is not picking up on. Not all events that occur with OSA are apneas. So, my recommendation is to see your physician and schedule a titration study, especially if it has been a number of years since your last titration, and to consider a full face mask.
The original poster uses SleepyHead. With that software, one has a pretty good idea when CA events are occurring especially when the machine is in Auto mode. I put the machine in Auto to narrow in on the best pressure and then switch to CPAP for fine tuning. Your points have some merit though and it may be time to switch back to Auto mode and see if there is something to be learned.
Opening your mouth and letting air out can be fairly easy to spot on SleepyHead as well. They start quite suddenly and have flat tops on the leakage graph, and end quite suddenly, often when you wake up...
I would accept a higher number of obstructive apneas if it reduced my central ones and lowered my totals. It seems like solving the obstructive issues is simpler since it is a question of pressure only. Complex apneas could have multiple causes. Causes that might not show up in a titration study. I have had a number of sleep studies and I find that doctors just use the data to suggest pressure settings. They don't make any money looking at your data. I need a doctor who treats the patient and not the data.
I have never had a titration study done as I went straight from a home sleep test to an APAP machine. However, my understanding is that they basically increase pressure in steps until your obstructive apnea stops. And if at some pressure CA events start to show up they back off from that pressure. It is all done in one night, or in some cases half a night (split study), so not a lot of data is collected.
It is not uncommon for CPAP pressure to cause central apnea, and if you did not have an significant amount of CA during the normal sleep study (without pressure), and it shows up with pressure, then the cause is somewhat obvious.
What I have found in my case is that the data goes kind of "mushy" with no real distinct cut off where obstructive apnea stops and central apnea starts while increasing pressure. One of my theories is that hypopnea can be either CA in nature (just reduced breathing effort without a full stoppage), or OA (flow is physically restricted). So, unless you look at each event close up with the SleepyHead expanded scale feature, you don't really know what they are. I also see events close together where a CA event turns into an obstructive event.
At the end of the day, I just did extended (2 weeks) at each pressure in CPAP mode and kept track of the AHI. My objective was to find the minimum AHI, and not worry so much about the breakdown of the total. What I did find is that my ResMed AirSense 10 in Auto mode did not find the optimum pressure well, and wanted to run higher than necessary pressures. I currently use 11 cm fixed, but the Auto mode wanted to run up to 15 cm or more. I think in part it was responding to hypopnea that were really central in nature, and more pressure caused more of them, not less.
There are not many doctors or sleep technicians that are willing to take the time do do all the testing to figure this out. All the detailed data is on the SD card, and they never even want to look at the SD card. Only summary data gets sent wirelessly, not the detailed data.
Thanks for your experiences. Right now I am working backwards from the APAP settings with the machine set in CPAP mode. I see that some of reported CA events are not true CA events, but I do find that they do nonetheless contribute to unproductive sleep. I seem to do better at a lower constant pressure. Still trying to find the bottom but I think I'm on the right track. I think I may have to accept the occasional spike in AHI due to the random nature of some CA events. It seems I have to find that sweet goldilock's setting where I average an acceptable AHI. Thanks again for your input.
