I struggle to understand how a five year old has enough strength to take down a healthy adult. Hurt them with their teeth or nails or bruise them with kicks, sure. but knock them to the ground so violently that they need to be hospitalized and intubated? Crazy.
Some special needs kids are pretty big for their age for some reason, and often special needs people are surprisingly strong and often prone to violent outbursts.
If she was caught off guard by a sudden attack, and was knocked unconscious, I could see the kid doing some damage by continuing to attack her.