[Diagnosis] where the high ODI comes from?

[pcstud]

I recently had the opportunity to do a lot of PSG research (I will write about it in a separate thread). I found something unusual. My apnea is characterized by a very high ODI, despite the apparently effective CPAP therapy. Mainly I have a hypopneas, apneas are effectively eliminated with CPAP. My doctor suggests a diagnosis for hypoventilation of obese people. Are there any other possibilities of ODI problems? With no PAP mu AHI is about 80, and odi 64. On CPAP therapy my ODI is between 10-30 (correlation with AHI). No centrals. Some paradoxical breathings.

[Gideon]

ODI - Oxygen Desaturation Index

This is one to check for when symptoms persist and Apnea numbers are low.
Checking is simple and with OSCAR can be correlated with CPAP data.  One simply gets one of the OSCAR compatible oximeters and tests Oxygen levels overnight.  
This is another reason for looking at full sleep studies instead of just the summaries.  Any user that has questionable desats should at least periodically monitor their overnight oxygen levels.

[Gideon]

Paradoxical breathing

is often a sign of breathing problems. It causes the chest to contract during inhaling and to expand during exhaling, the opposite of how it should move.