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Fluctuating AHI

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  • Fluctuating AHI

    im new to forum,female 53yr. Test showed AHI 69. Been on CPAP resmed air sense for about 5 weeks. Using f30 mask and humidifier. Pressure is 13. Initially 12. Turned up myself as getting such variation in AHI. Anything from 1 to 23!! Air leak always low or within norms. Gives me an average monthly of about 7. Anyone else have such variation?

  • #2
    I’m not a sleep technician and this is blind guess work, but with fluctuating AHI, my mind immediately jumps to central apnoea/complex apnoea. Believe it or not, having the pressure too high can cause central apnoeas in some. If lower pressures aren’t enough, and higher pressures cause central apnoeas, they usually switch you over to BiPAP.

    Have you had a look at the SD card? I know a lot of people that manage their own pressure usually look at the SD card data with something like Oscar. (If you’ve never done it before, make sure you always lock the SD card with the switch on the side, before plugging into your computer, and unlock it before placing back into the machine.)

    It’s usually best to look at the data first before acting because the machines may misinterpret an apnea event. (like when you wake up or nock the hose) Looking at the data helps show what is actually happening. If data does show central apnoeas at higher levels, you could try a “poor mans bipap” by turning on the exhalation relief. Think it’s called EPR on ResMed.

    Was your average AHI worse on 12cmH2O? Does it still fluctuate on 13?

    Someone from Intus will pop by, probably by Monday. They’d probably know more than me.

    - Reno


    • #3
      I forgot to mention small fluctuations are normal. But large fluctuation aren’t.

      I’m usually 1-4 |(avg around 3). I think 1-23 is crazy, though. But if it only went to 23 one random night, but most of the time it’s around 7, I’d shrug it off as an anomaly.


      • #4
        Thanks Reno. Lots of good advice there. Will definitely check the sd card tomorrow. The fluctuation is on 12 and 13. Have been looking through the forum. I get a lot of thoracic muscular pain anyway and sometimes take small dose diazepam at night. I’m going to keep a record to see if they match up. Really appreciate your response.


        • #5
          Oh that makes a lot of sense. CNS depressant can make sleep apnoea worse, so could possibly be diazepam. I don’t know what you pain management is, but opioids could also make sleep apnoea worse. Most likely worse than diazepam. Something to bare in mind if you use something like co-codamol.

          You might just need a higher pressure on days you take diazepam (or certain painkillers).

          Edit: Alcohol is also a CNS depressant. Could just be one factor or multiple things combined like alcohol + diazepam that make things worse. Not sure that is the case, but worth baring in mind when keeping a record.


          • #6
            Good Morning,

            Thank you for your post

            If you have the ResMed Airsense10 fixed pressure CPAP machine, have you created an account on the ResMed MyAir website so you can view your data? -

            If you got your machine from the NHS then I would suggest to contact them for them to review your data, and your pressure requirements to see what is going on, and to check your mask as your target AHI with a CPAP machine is an AHI of 5 or under.



            • #7
              Thanks Kelly. Have got app and it’s really good. Sleep clinic have put pressure up to 12.6 and EPR upto 3. Results were AHI 33.2!! Did have a 28litre leak though. Trying same again tonight. Hope it’s down to the leak. If not leak will put EPR back to 2.


              • #8

                Thank you for your reply.

                See how you get on tonight

                If the leak is the same, then I would suggest looking at the following

                We normally would ask you to check the following
                1. How do you breathe? Through your nose only or your nose and you mouth? If you nose only then you need a nasal mask. If your nose and your mouth then you need a full face mask. Do you have the right type of mask for how you breathe?

                2. Sizing - Do you have the right size cushion for your face? If you find the mask you have on our website then there should be a sizing guide on the downloads tab on the mask product pages. Simple download this and print out at 100%. Follow the instructions to measure your face to see which size is correct for you.

                3. RemZzzs mask liners - These are a soft cotton fabric liner creates a barrier, absorbs skin oils and reduces air leaks as well as skin irritation and pressure marks. Try a sample pack for just 6.99. Here is a link to the product page - - Just scroll down to the compatibility chart to find your mask / mask size and then this will tell you which options to select.

                4. CPAP Pillow 2.0 - - This is a pillow for side sleepers who roll over in their sleep and knock their mask. Part of the pillow on each size is cut out so your mask over hangs the gap rather than knocking the seal on your mask.

                5. Age of cushion - how old is the cushion in your mask? sometime the wear and tear of the mask can affect how good a seal you get. It might be worth looking at replacing the cushion of the mask if older than 6 months.

                If you have any questions or if I can be of any further assistance then you can either message me on here or email me at



                • #9
                  Thanks Kelly. I’ve ordered the liners just. Getting irritation so will be good to give them a try


                  • #10
                    Good Morning,

                    Perfect. Hopefully they will do the trick. Please let me know how you get on.



                    • #11
                      I'm curious if the sleep clinic looked at the data, particularly the flow rate data. If they didn't see anything alarming in your breathing pattern or talk much about central apnoea, that does point more to either lifestyle patterns, or problems with your sleeping set up.

                      Definitely keep track of alcohol/medication day to day to see if there is a pattern in your AHI fluctuations.

                      Also maybe double check your hose doesn't/cant kink, or reduce the airflow in some way, because this may confuse your machine into thinking it's at the right pressure, but you may not have the right amount at your mask. I use a strap on the side in my bedroom to raise my hose up above me, so it doesn't tangle or kink. There are also products that do the same thing. but DIY didn't cost me anything xP.


                      • #12
                        Thanks Reno. Just thought I’d update. I am now on pressure support 14 with expiratory of 2 and am now getting much better figures. Over 2weeks having couple episodes over 5 and the highest was 10 AHI. Most of the time it’s 3 or below. Thanks again


                        • #13
                          Thanks for the update. I’m glad most of the time it’s below 3. Good to get get a good night’s sleep!


                          • #14
                            I wanted to start measuring AHI, do you need any machinery - didnt understand how i would record an apnoe event etc.


                            • #15
                              Good Morning

                              Thank you for your post.

                              When you say you want to start measuring your AHI, have you been diagnosed with sleep apnoea, or are you looking to be tested for sleep apnoea?

                              Please advise as AHI events can be recorded during a sleep test, or when using a CPAP machine, but you need to have a diagnosis of sleep apnoea to use a CPAP machine.