I was tested for sleep apnea at home and had the following results:
Sleeping on left side - 2 AHI Sleeping on right side - 16 AHI Sleeping on back - 56 AHI
Average for night - 6.7 AHI
I got a test machine and using nasal mask average over 2 nights was about 2.5 AHI (and felt better the following days).
Just got Resmed Airsense 10 and used with nasal pillow for first night. Here are my results:
Total Time - 7:37 Events per hour - 16.5 Seal - Good Humidifier - Good Pressure 8.3 Leak - 5 L/min AHI - 16.5 Total AI - 15.4 Central 15.2
I have no idea what these figures mean except that the AHI was far worse than when I did the sleep study. Any help appreciated.
Those results are a little puzzling. There is some important information missing that is needed to make some sense of it though. Some questions:
Does your sleep study report give you an incidence of central apnea results that makes up the total for the night of 6.7 AHI?
What was the brand and model of the test machine, and what was the set pressure if it was a CPAP, or minimum and maximum if it was an APAP (Auto machine)?
Is your ResMed AirSense 10 an AutoSet or APAP machine? What are the set pressures on it? When you first turn it on, the display will light up and the number in the middle of the circle is the current pressure which may be your start pressure. In the top right of the display will be the minimum and maximum pressures if it is in APAP mode.
1) I don't have the sleep study report, just got the numbers verbally from the respiratory therapist. Sounds like I need to get the report.
2) Test machine was ResMed Airsense 10. I think it was AutoSet but not sure.
3) The machine I got for daily use and used last night is AirSense 10 AutoSet. Set pressures are 4 to 20.
What does the Leak number mean? A leak in the machine, a leak in the mask seal or air leaking out of my mouth? I tend to be a mouth breather.
I take it you are getting these values from the sleep report on the AirSense machine? If so have a look at page 19 of this AirSense technical manual for an explanation of what they are. The leak rate you have is very low, and I would suggest you are not losing air out of your mouth based on that low number. It is the 95% leak rate which means during the night your leak rate was below that rate for 95% of the time. To get a happy face for leak rate you only need to have a leak rate less than 24 L/min for 70% of the night. It is a very lax target, and the number value is more accurate. I try to be under about 16 L/min.
Yes, you should ask for a written copy of the sleep report for your records. It should give a lot more information and include your oxygen values as well.
You should ask the clinic for details on how the test machine was set up, compared to where you are with your own machine. There seems to be a very big discrepancy in the effectiveness.
If you have a PC or a Mac with a SD card reader I would suggest you download SleepyHead. It is free software that lets you look at how your machine performed. It gives the time of each apnea event on a graph along with many other variables. I find it essential in monitoring my machine performance. Here is a link to a basic instruction manual. If you need any help just ask.
Who is setting up your machine for you? Yourself, or a sleep technician? Your current settings of 4-20 cm are the default out of the box values, and probably could be optimized at least for more comfort, and possibly better performance. The red flag however in what you have reported is the frequency of central apnea events. A CPAP using pressure does not address central apnea very well, and in fact the AirSense is programmed to ignore it and not increase pressure. In some individuals starting CPAP treatment can increase the frequency of central apnea. I am one of those individuals. However, my increase was not as high as the 15 range you report.
Your Airsense 10 reports what is called "unintentional" leak. Every mask has an exhalation port where the air comes out. If it didn't then, because air is constantly being pumped in, you would blow up like a balloon and float away. It also allows exhaled CO2 to be exhausted so that you don't re-breathe it. So, no matter how well everything is working there will always be a certain level of leak. This is the "intentional" leak. Your ResMed machine takes a stab at what it thinks the intentional leak rate should be, largely based on the type of mask you tell it you have, and subtracts that from the figure it reports. So, in theory, if your mask is fitting very well then you can have a leak rate of 0. 5 L/min is till pretty good. Other CPAP machines just report total leak which will include both intentional and unintentional leak. For this reason you will find that your leak rate doesn't relate to those reported by people with different brands of machine.
The problem with the ResMed method is that the machine doesn't actually know what the intentional leak levels really is, it just approximates it. However, it can easily be incorrect if you don't use a ResMed mask, you haven't set the correct mask type in the options, you have facial hair and so on. The unintentional leak rate is still useful, but it needs to balanced with a bit of thought and experience. If your machine thinks your mask is leaking but it's quiet, you're comfortable, you're partner reports no odd noises, your AHI is good, you are sleeping well, etc, then it's probably not a big deal.
Thanks for detailed reply. Yes, results are from the sleep report on the AirSense machine. I am a physician so technical manual is great. I already downloaded SleepyHead, but I don't have an SD card in my machine. Resmed says to only use theirs for "safety". Should I buy one from them or just get one? If not using theirs is there a safe card to use? I am setting up the machine myself. Got through Apria Healthcare (they contract with Kaiser, my insurance). If I understand you correctly the CPAP is taking care of obstructive sleep apnea but possibly causing central sleep apnea?
I believe just about any SD HC card will work. The ResMed branded card that came with my machine is a 4 GB SD HC. The machine will format it when you put it in the slot, and let you know if there is a problem. Good idea to save that technical manual as a PDF. They come and go on the internet.
As you are a physician you may be interested in and also will understand this technical article on what is called Emergent Central Sleep Apnea. I think the short story is that only a fairly small number of OSA diagnosed patients develop the issue of emergent CSA, and of that small percentage the issue resolves itself in about 75% of the cases in about 6-8 weeks. You are probably aware that the treatment goal for apnea is an AHI <5. My thoughts are not to worry too much unless the CSA does not start to come down. If it doesn't then you may need a BiPAP machine which may provide a small benefit, or an ASV machine which will be more effective. My understanding is that in the US the routine is that an APAP is tried first. If it fails then the BiPAP, and if it fails then the ASV. There are some heart condition issues that have to be evaluated before it is safe to use an ASV though.
Hope that helps some. If you are interested I can tell you how I have set up my machine.
Thanks for the article, very interesting. Yes, I am definitely interested in how you have set up your machine.
To be clear while I am a retired professional with a technical background, but I am not a physician or a sleep technician. These initial settings are for comfort only and each user tends to set up their preferences a little differently, but here is basically what works for me, to be as comfortable as possible to go to sleep each night. They are listed in the order they appear in the setup menu.
Minimum Pressure: 7 cm
Ramp Time: Auto
Start Pressure: 7 cm
EPR: On
EPR Type: Ramp Only
EPR Level: 3
What this will do is start you out with an Inhale pressure of 7 cm, and with the EPR (Expiratory Pressure Relief) setting of 3 cm, it will reduce the pressure to 4 cm which is the minimum for the machine on each exhale. 7 cm to most people feels very comfortable. It should feel like you are getting air in very freely without any restriction from the mask. Exhaling against 4 cm is easier, and the machine can't go any lower. This will continue at these pressures until the machine decides you are asleep. Then it ramps up to the minimum pressure of 7 (and it is there already). But the EPR will stop, and you will be exhaling against 7 cm, which should be comfortable as you are asleep. The purpose of using the auto ramp is to enable the EPR to only be used during the ramp period. Since apnea is as likely to occur on exhale as on inhale, the higher exhale pressure will be more effective in treating the apnea. The machine will not have to ramp up as soon to stop apnea occurring. In my case shutting the EPR off during sleep reduces the maximum mask pressure by about 2 cm. But that is kind of an individual thing.
This said I would consult with your sleep clinic and get some advice on pressures they used during your CPAP trial which looked pretty good. You should tell them about the high central apnea too, and get their opinion on that. They may want you to come back in for a titration study to find out at what pressure you may be more susceptible to central apnea. With SleepyHead you will also be able to observe that for yourself. It flags when events occur, and you will see what the pressure is. The other thing that SleepyHead will flag is the time one is in Cheyne Stokes Respiration (if at all), which is a specific type of central apnea. CSR can run up the central apnea count quite quickly.
For now it shouldn't hurt to leave your max pressure at 20. Down the road when you see what is going on with SleepyHead and get some advice from your clinic you may want to reduce that. If pressure is inducing your central apnea it may be necessary to limit the pressure and allow a little more obstructive apnea, but get less central apnea. That 8.3 cm pressure you saw reported is the 95% number, so 95% of the time your pressure was under 8.3 cm -- which is quite low. When you get more data and advice from your clinic, it may be possible to lower your maximum pressure to 9 cm or perhaps even less.
In my case I have made pressure changes over 20 times trying to find an optimum. What I found is that I was setting the minimum and maximum closer and closer together. In my current mode I have the maximum set at 12.2 cm and the minimum at 12.0 cm, or in other words essentially in fixed CPAP mode. Only 4 days into that mode, but so far my AHI is down noticeably. It seems possible that a fixed pressure during the night may do just as well or better than the machine's fancy algorithm constantly changing pressure all night!
Hope that helps some. Any questions just ask. Pages 2-11 in that technical manual is a good read. I believe Cheyne Stokes is explained as well.
Thanks for your observations. Of course, my first plan is to see sleep apnea specialist (hasn't happened yet because Kaiser has respiratory therapists as first line) so he can go over my findings and suggest the best route forward. I may wait a bit before trying the machine again as I was far worse with the sleep machine than without and didn't feel good this morning. I still have to work during the week! Your experience gives me good guidance on what to ask about.
One thing to keep in mind is that at least in my case the contribution of central apnea events varies widely from night to night. My worst is about 8 and best essentially zero. I have blamed centrals on many things, and just when I think I have it figured out and have them under control they pop back up again.
At times I think the barometric pressure influences it. I am fairly certain that a poor sleep due to an uncomfortable bed, or a new mask I am not used to, or the room is too hot, or I am trying to sleep too many hours in a night, does increase the central count. I have blamed my beta blocker bisoprolol for reducing my blood circulation rate and increasing centrals. I convinced my doctor to reduce my dose, and initially thought it made a big difference, but now perhaps some, but not a huge effect.
I guess the point is that you are unlikely to get a handle on it based on one night's sleep. It will take some time to get data and make a connection to the trigger.
I decided to try your settings and in addition set a maximum pressure of 9. There is no way I can do worse than I did last night (which is a lot worse than not using the machine at all).
Did you manage to get an SD card? Capturing data to view in SleepyHead will be most revealing as to what is going on.
Yes, I put in a 32 GD SD HC card and the machine didn't complain.
That should be good for about 10 years of data!! When you put the card in the slot a grey screen should display saying it is preparing the card.
It is probably good to set your max at 9 cm. That is going to let your machine use a reasonable range of pressures, and you will be able to see when CA's occur and at what pressure.
Follow-up: Turns out I had prodrome of viral infection the first night I used CPAP machine. After mostly recovering, I tried again last night with maximum pressure set to 9. Results: AHI - 1.0 Central AI - 0.7. Feel well rested this morning. Not sure of the reason, but problem resolved itself!
Central apnea is something that seems to never be consistent. I certainly have not figured out what makes it come and go. My thoughts are that if AHI averages under 5 then it is not too concerning. If averages get above that, then it probably needs further investigation.
If you keep monitoring your results with SleepyHead you may be able to further refine your pressure settings.
