What sleeping face down would gain is the force of gravity pulling the tongue in a direction directly away from the airway.
As far as the above charts go, if one were to sleep face down on a massage table, the head would be in a position like B and not like C. This is the position you lie in when getting a massage.
I believe with your head in position C, any body position you could take would still leave you uncomfortable after a few minutes.
There is something fishy about those charts that I hope someone can explain. In 'A' the lips are closed. In 'B' they are slightly open and in 'C' the mouth is wide open. To me, the opening of the mouth is what gives an appearance of a wide airway. I believe figure C could have been drawn with the head in position A and with the mouth open you would get the same appearance of an increased airway space.
But maybe the charts aren't really so fishy. The charts were drawn to illustrate how intubation is easier if the head is tilted back. This is just saying it's a "straight shot" for pushing in the intubation tube in position C. It says nothing about less inclination for the airway to collapse during sleep in position C. Of course you just believe it is worth further investigation and despite my doubt that it has any value for apnea patients, I like that people investigate new things for our possible benefit.
