Difference Between Central Hypopneas and Central Apneas?

Does anyone know what the difference between a central hypopnea and a central apnea is?

The definition of obstructive apnea, as I understand it, is obstruction preventing all breathing. A central apnea occurs when you just "forget to breathe" or stop breathing for reasons other than obstruction.

An obstructive hypopnea is reduced breathing through a partial obstruction. So a central hypopnea is....forgetting to reduce your breathing, even without an obstruction?

That sounds crazy, so help me understand this. Either you forget to breath, or you don't forget. How can there possibly be a difference between central hypopnea and central apnea?

I am not certain but the concept of a central hypopnea seems to be to be an oxymoron - by this I mean that a central is no breathing effort but a hypopnea is breathing (but limited). Thus, how can someone be breathing (hypop) & not breathing (central) at the same time.

But as with all terminology, logic doesn't always play a part

Anyone else got a thought ?

DSM

A central hypopnea essentially translates to shallow breathing (or non-repetitive hypoventilation). There is no sign of obstruction (i.e. no snore, no flow signal flattening, etc.). And the shallow/central muscular breathing effort is not atypically coordinated in an out-of-phase manner.

Here are some apnea and hypopnea scoring definitions that might help:
http://www.sleepreviewmag.com/issues/ar ... -04_07.asp