Hypopneas and Respiratory Obstructions

[dataq1]

Are hypopneas always caused by partial obstructions? Are there other physiologic/neurologic causes for a decrease in flow that meets the hypopnea criteria without an accompanying desaturation?

[Gideon]

If you look at a CO2 induced breathing with the waxing and waning you have a very common example of what you are looking for that is very often associated with central apnea.

[dataq1]

Intuitivley, it seemed to me that Hypopneas likely arose from either partial obstructions, neurologic signals, or response to pain (for example, injury to the chest/diaphram from trauma or surgery), lastly cardiac feedback (as in congestive heart failure)

Pressure applied with Cpap or Apap is only going to address partial obstructions, as "splinting" of the airway would likely not impact those others causes. Does that make sense? 

However, you have raised an interesting question.  While asleep, does the brain, recognizing a CO2 "surplus" instruct the respiratory not only how often to inspire but how deeply to inspire?