[CPAP] Varying measurements from AS11 and Oxymeter

[fuzz]

Hi, all,
I've been normalizing with the AS11 and I am only 1 month in to my CPAP adventure. I am confused by conflicting measurements. I feel better than in years but I am a data guy (new to this area) and am getting confused by seemingly different measurements of the same thing.  I'd appreciate some help with intrepeting these results and understanding the deltas between two things that are allegedly measuring the same thing but through different means: 

OSCAR from last night shows AHI of 6.03. 
My Sleepimage 02 measurement device says AHI of 3% / 21 incidents per hour. 

Thanks in advance!

Attachments are OSCAR and SleepImage reports for the same sleep period.

   

   

   

[fuzz]

Just giving this a bump ...

[fuzz]

From my doc:

"The AHI from CPAP will always be less than Sleep Image as it under represents the true amount of events that occur. The way CPAPs measure pauses in breathing is inaccurate. It is one reason we use the sleep image ring."

[dataq1]

From my doc:

"The AHI from CPAP will always be less than Sleep Image as it under represents the true amount of events that occur. 

However, as i read fuzz’s original post the breath-measured (Resmed device) AHI is actually greater than the oximeter-inferred (Sleep image device).

IMO, A patient needs to consider the what the doctor considers significant.  It is perfectly reasonable for the doc to consider significant desaturations as clinically important. (Assuming that the desaturations are measured accurately and are of a duration that impacts health). That is the reason that AASM requires a desaturation to identify apneas.

OTOH, breath-measured apneas (10 second pauses in ventilation) may or may not cause a desaturation, thus may not impact blood chemistry. But these same apneas may or may not cause sleep disruption.

So, IMO, the focus of the doctor is an important consideration. If the doctor is primarily concerned with disruption of blood chemistry versus being primarily concerned with possible sleep disruptions.

From the American Academy of Sleep Medicine criteria, desaturations are a requirement for apnea identification. 

Unfortunately breath-measured devices only SUGGEST that a desaturation may occur.

[fuzz]

Thanks so much. Actually the CPAP said that I had AHI of around 6, and the oxymeter told me an AHI of around 20. But I agree with everything else you're saying and thank you for your answer. 

Nick

[TechieHippie]

It looks to me like the baseline used to calculate 3% drops was higher than it should be. I looked at the graphs to compare roughly equivalent times. Your flow rate seemed okay in Oscar for things marked as apnea in the oxygen report. You had only one minute under 90% and no significant amount of time lower, and mean was 95 which is good. There's room for improvement but overall a good enough oxygen graph. This seems consistent with the Oscar results, so I would say to trust Oscar for the AHI number unless you need the higher one to justify proper treatment.

[ahuman]

Is that variane within the margins of error of the two devices?

[fuzz]

Forgive me, but I am unable to answer that question.

[fuzz]

Many thanks for this input, truly.