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Correlation to Keto- AHI has skyrocketed
#21
RE: Correlation to Keto- AHI has skyrocketed
The high PS will most likely cause CA again.

Here is a basic rundown of PAP.

CPAP in its basic form is meant to apply pressure to your airway to prevent it from collapsing. You still have to breath spontaneously. Because breathing out against pressure can actually make breathing more difficult they realized that pressure support (which provides ventilatory assistance) was often required to make CPAP comfortable.

Although CPAP and APAP machines have pressure support it is limited to 3 cm or less (under half what you are using) so that patients don't over ventilate themselves (like you are).

Bilevels remove the chain and allow higher pressure support to be used. Bilevels are meant to be used in people with breathing issues like COPD, central apnea, obesity hypoventilation syndrome, neuromuscular disorders etc that require ventilatory assistance. Within this group of people 6.5 cm PS like you have been using is on the higher end of what we usually see (4-6 is most common). Usually you have to fail CPAP/APAP (even if you have one of the above breathing issues) before a doctor will prescribe a bilevel, in your case I am guessing you bought one used?

You have admitted you are using a high PS because you played with settings and didn't know better. Setting PS to target comfort while awake and chasing the lowest AHI possible are two common mistakes. It is best to learn the basics before you start messing with things like ventilation assistance otherwise you can end up in issues like you did. Looking at those 3 pre keto examples you can see some green areas (periodic breathing) which are minor central apnea effects, you appeared to be on the edge of apnea and intermittent fasting/keto just were enough to push you over the edge. Not sure how the fasting/keto had this effect but I do believe you shouldn't need 6.5 PS as it sounds like you are fairly healthy (talking about biking long distances etc) and shouldn't need ventilation assistance.

From the limited information available I would say stick with PS of 3. To give further advice I would like to know what your original diagnosis was (sleep study AHI, all obstructive or some central? etc) and see what results continue to look like at lower PS.
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#22
RE: Correlation to Keto- AHI has skyrocketed
Thank you. Appreciate your explanation. Have changed the PS to 3 and will report back!
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#23
RE: Correlation to Keto- AHI has skyrocketed
Updated from last night, looks like there are still some issues- should I move the PS to 2?

   
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#24
RE: Correlation to Keto- AHI has skyrocketed
I’m interested in your thread. I’ve been low carb for many years, sometimes keto (and tested with urine strips). My understanding is CO2 affects blood PH, and I think Keto can affect blood PH too.

The advice you got here has brought you to below 1 AHI. The green Periodic Breathing is still there, but few CA’s. I tend to pause for a couple days at an improved setting to see how things settle out. But maybe you could ignore that and try to see if the reduction in PS is even better (and then pause there).

I miss my Philips Respironics reports of Periodic Breathing now that I’ve switched to ResMed, but what ResMed shows that I never had a graph for before is Flow Limitations. Do you have that graph? If so, it could give you at-a-glance if you are getting too low. If not, you’d have to zoom in to a 3-minute window (or less) to see the breath waves and their shape to see if they are round or flattening on top (if flat then you are approaching too low pressure).

- SleepyCPAP
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#25
RE: Correlation to Keto- AHI has skyrocketed
Rob - I'm interested in your flow rate pattern since you dropped your PS. Would you provide a screenshot of a 2-minute segment of the Daily screen that includes the Flow Rate graph?
Crimson Nape
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Useful Links -or- When All Else Fails:
The Guide to Understanding OSCAR
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#26
RE: Correlation to Keto- AHI has skyrocketed
Wasn't sure what you were looking to see so I took 3 including 2 events

           
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#27
RE: Correlation to Keto- AHI has skyrocketed
Your AHI is fine, the periodic breathing is still a central apnea type effect but not as worrying.

Did you end up quitting keto as you mentioned you were going to do? Mostly curious if you are out of ketosis now?

What is your height and weight?
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#28
RE: Correlation to Keto- AHI has skyrocketed
Yes, bailed out of Keto the first day of my post, definitely out of ketosis, I could tell just by my cycling performance on day 2 (way more power). Currently 191cm at 300lbs (BMI 37). I tweaked PS to 2.5 and brought the EPAP up .5 to 8.0 and now I'm leaving everything in place to settle and see where things go.

I'm waiting to get the initial Sleep study, but confirmed my diagnosis was OSA, no CA referenced around 6 years ago.

   
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#29
RE: Correlation to Keto- AHI has skyrocketed
Rob - You asked why I wanted the 2-minute view. I would have expected coming from a PS of 6.5 to 3 would show up flow restrictions if you needed that much pressure originally. From what I see, the PS of 3 seems to be at, or near, the correct pressure. To me, this would mean that you were over pressuring, thus could be causing sleep disruptions to occur. Thank you for showing this. Does the lower PS feel any better?
Crimson Nape
Apnea Board Moderator
www.ApneaBoard.com
___________________________________
Useful Links -or- When All Else Fails:
The Guide to Understanding OSCAR
OSCAR Chart Organization
Attaching Images and Files on Apnea Board
Apnea Helpful Tips

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#30
RE: Correlation to Keto- AHI has skyrocketed
When I first started last night after moving the PS to 2.5 from 3 the pressure felt a little light, so I bumped the EPAP to 8 and felt great. 

Would love to see the CAs go away completely- but assuming I need to give it time. 

I hope my uneducated previous settings of a high PS didn’t create any kind of long term issues
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