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AHI radical changes???
#1
Question 
Started CPAP a month ago. I have no problem sleeping with my mask. My pressure is between 12.5 and 15 cm of water. Started with a FIT 10 mask because of mouth breathing. AHIs were all over the place. Originally had a 25.9 AHI and with treatment I got 10 then 5 then 15, 12 and 7. Then 17 and 5 - you get the picture. Had trouble sleeping on my side with the full face mask. Switched to a WISP with a chin strap. AHIs immediately went down dramatically - 1.6, 2, 1.9, .68, .4. Unfortunately, I began to develop a huge bruise on my nose. Tried a gel strip but that didn't help. Because of the bruising I used the Fit 10 mask again last night and the AHI went to 14. Am going back to the clinic tomorrow to see what can be done about the nose problem.
The PA that is monitoring my CPAP treatment says that I am too number oriented and that the machine is not all that accurate with these AHI numbers. He says that if I want to know if the treatment is successful or not I should go back in and have another sleep study session.
My questions are: Is the ResMed machine that inaccurate that I can't get a fairly good indication of the successfulness of my treatment? Is it possible for the AHI numbers to change so dramatically by just changing the mask (I did reset the machine for the change in mask)?
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#2
(09-12-2016, 09:38 PM)elbie Wrote: The PA that is monitoring my CPAP treatment says that I am too number oriented and that the machine is not all that accurate with these AHI numbers. He says that if I want to know if the treatment is successful or not I should go back in and have another sleep study session.
My questions are: Is the ResMed machine that inaccurate that I can't get a fairly good indication of the successfulness of my treatment? Is it possible for the AHI numbers to change so dramatically by just changing the mask (I did reset the machine for the change in mask)?

First, about the accuracy of a sleep study. It is a snapshot in time under challenging circumstances and does not represent your medical condition with any degree of repeatable precision. Therefore, it is a starting point to develop an informed diagnosis and some initial titration guidelines.

Second, about the accuracy of your machine -- or any machine for that matter -- they are not precision measurement devices and use only a few parameters from sensors to algorithmically compute the scores you are seeing displayed. It is the trend over time that really matters, not the day-to-day readings unless they are repetitively poor.

Third, about the mask. Leak rates do directly affect the sensors and can alter results dramatically. You find the mask that appears to produce the best results and one that is not uncomfortable to use. It takes experimentation and some tweaking. I have not met anyone that did not spend time, effort, and money on trying to find a better mask setup.

Fourth, about you personally. Some of us, myself included, are analytical and wish for a precision machine that yields accurate numbers. Since we do not live in a sleep lab, this is a matter of approximation not precision. My medical mentor in the old days cautioned me to treat the patient, not the machine. And that chasing numbers was often futile over the short-term. It is like watching a patient with PEA (Pulseless Electrical Activity) that appears to have a somewhat normal EKG, but their heart is not pumping blood and they are dying.

Fifth, and lastly, whether or not your therapy is working is subjective. How do you feel? Are you symptom free? Has your quality of life improved? AND DO THE NUMBERS LOOK REASONABLE OVER A SUFFICIENT PERIOD OF TIME?

I suggest you do what I do. Track the numbers, take screen snapshots of some of the anomalies, and when you have questions based on accumulated data, make an appointment with your sleep doctor (not the DME's respiratory therapist and not a physician's assistant -- unless they are a nurse practitioner skilled in sleep disorders) to discuss your findings, conclusions, and a course for the future.

Best of luck.
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius
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#3
Hi elbie,
WELCOME! to the forum.!
Hang in there for more responses to your post and good luck to you with yourCPAP therapy.
trish6hundred
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#4
If you are a numbers person, download the "SleepyHead" software (there's a link at the top of this page; under the large print words). Collect some data, then post some pics here (somebody have the link for "how to prep sleepyhead pics for posting?) and people can help you to understand the graphs. There is a TON more data available than just the AHI numbers.
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#5
I have also found that changing masks, let alone changing mask types, can affect the AHI. Some of this might be short term with you being less deeply asleep the first couple of nights on a new mask. Breathing in and out feels very different between a FFM and nasal pillows, at least to me. And unlike a sleep study, the machine does not know if you are sleeping or tossing and turning. If the different mask keeps you awake, this will be scored as a higher AHI, but would be ignored in a sleep study.

Part of this might be differences in leak rate. Part of it might be difference in air pressure if your nasal passages are restricted. Using pillows or a nasal mask (depending which one) will cause your nose to puff up a little (more pressure inside than outside) which can affect your breathing. With a full face mask the pressure is the same so this won't have an effect.

As others have said, if you like data then get SleepyHead. AHI is just too coarse of a measure to be useful day to day.
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#6
(09-12-2016, 09:38 PM)elbie Wrote: Started CPAP a month ago. I have no problem sleeping with my mask. My pressure is between 12.5 and 15 cm of water. Started with a FIT 10 mask because of mouth breathing. AHIs were all over the place. Originally had a 25.9 AHI and with treatment I got 10 then 5 then 15, 12 and 7. Then 17 and 5 - you get the picture. Had trouble sleeping on my side with the full face mask. Switched to a WISP with a chin strap. AHIs immediately went down dramatically - 1.6, 2, 1.9, .68, .4. Unfortunately, I began to develop a huge bruise on my nose. Tried a gel strip but that didn't help. Because of the bruising I used the Fit 10 mask again last night and the AHI went to 14. Am going back to the clinic tomorrow to see what can be done about the nose problem.
The PA that is monitoring my CPAP treatment says that I am too number oriented and that the machine is not all that accurate with these AHI numbers. He says that if I want to know if the treatment is successful or not I should go back in and have another sleep study session.
My questions are: Is the ResMed machine that inaccurate that I can't get a fairly good indication of the successfulness of my treatment? Is it possible for the AHI numbers to change so dramatically by just changing the mask (I did reset the machine for the change in mask)?
I was given a different mask because of the ulceration at the bridge of my nose. I am now using a nasal pillow with a chin strap.
I am going to try to attach 3 screen shots. The one from 9/2 was when I changed to the WISP, the 9/12 is one of the days I used the full face because of the sore on my nose, and the 9/13 is the first night I used the nasal pillow.
Any comments?

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#7
You will need 4 posts to make attachments. I think the suggestion that machine data is bogus is completely wrong. It's not a polysomnography but it's pretty good, and studies comparing sleep data and machine data have proven that. Give your technician a copy of this: https://www.researchgate.net/publication...omnography Study is old, and I think there are updated studies that show better correlation.

Good luck healing your nose. Clearly you have better results with nasal therapy, and perhaps the nasal pillows will also work well for you.
______________________________________________
Organize your SleepyHead Data
Post your SleepyHead Data from Imgur
Robysue's Beginner's Guide to Sleepyhead
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#8
I kept trying to put the screenshots on my Post but couldn't do it. So you are saying I need to post 4 times to be eligible?
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#9
The Wisp mask should be worn fairly loose. I use it and at first I had red marks on the bridge of my nose. When I loosened it no more marks and I don't hardly feel it is on. Suction is supposed to keep it it place.
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#10
(09-14-2016, 10:11 PM)Sleeprider Wrote: I think the suggestion that machine data is bogus is completely wrong. It's not a polysomnography but it's pretty good, and studies comparing sleep data and machine data have proven that. Give your technician a copy of this: https://www.researchgate.net/publication...omnography Study is old, and I think there are updated studies that show better correlation.

Nobody is suggesting that the machine data is bogus, but that it is an algorithmic approximation based on a few airflow sensors and that the reported results can be significantly affected by external factors like mask leaks and positioning. It will never be as accurate as polysomnography because you would need the EEG data to truly determine if you were asleep. Not to mention all the sleep/wake artifacts that are created, which affect the scoring, but may appear to be grossly irrelevant.

ResMed has a proactive research team and supplies equipment and funding (as do the other major vendors) for studies, but ResMed has, by far, the most numerous impact on the literature.

One study concluded: "Using the same airflow signals as those of the CPAP device, a strong correlation between the AHI-PSG and the AHI-S8 was observed. However, the correlation was weakened when the analysis was limited to the HI." http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854701/

Again, it is a question of how you feel and the broad data trends, not the individual numbers on a night-to-night basis that should be considered useful.
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius
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