I agree with Shay, it's unbelievable. Once you pass out and the carotid compression continues you never regain consciousness, nor do you feel anything (unconscious), nor can you take any action in freeing yourself (unconscious).
But in contrast to Shay, I believe for sure unconsciousness is not strong enough "to free you", there is no directed action when unconscious.
My only explanation (apart from being saved by someone, broken ligature, etc.) would be that convulsions were intense and therefor you slipped out of the noose, coincidentally.
The other explanation, for me, would only be, you were not unconsious yet, but drowsy by the valium and the other drugs you ingested!
Finally, the link to lostallhope: it's crap. Lots of false info.
Sorry!