Schiavo most likely put Terri in a carotid choke the night she collapsed.
Quote from the book "Silent Witness" (page 113): "Michael and Scott [Schiavo's brother] once had a physical fight in the Schindler's kitchen. Michael put Scott in a carotid choke hold, but Scott was able to get out of it, and the two wrestled on the floor."
I'm still fascinated with the highly unusual injuries shown by the bone scan, namely, the compression fracture on her spine along with injuries to the back of adjacent ribs, and the bone bruise on her right thigh. That gives a picture of two blunt objects pushing against her back and leg with enormous force. It's hard to imagine what could apply such force at those two points but Michael's knees, pinning her down as he cut off her oxygen.
Note that those injuries cannot be attributed to resuscitation efforts, which sometimes injure ribs from the front but not from the back.
I do not think Terri "collapsed." I think she must have been wrestled to the floor.