I work in one of the best trauma centers in the country, so we get pretty much every trauma and probably-not-trauma within a 4 state radius. I see the difficult decision to take a patient off a ventilator and make them “comfort care” made everyday. There’s no set amount of time. It depends if she remains unresponsive and unable to make decisions for herself and does not have a POA or medical directive. It can be days though. Brain death testing is usually done a few days after the initial incident, it is not an overnight thing.
Also, I’m not as familiar with OD’s as I am with hangings or self inflicted injuries, but I can say if they caught it in time and they went to the effort to airlift her, that’s a good (or bad, depending how you look at it) sign. They must have caught it pretty early.
As for her being ventilated, that’s not a big deal, to be honest. Working in a trauma center, I would say more patients are ventilated than not. Again, it just depends on the extent of her injuries. If she’s in a medically induced coma that does mean she must be showing some signs of brain activity. People that remain unresponsive even off sedation or meds to keep them in a coma tend to be the ones who don’t fair so well.
Sorry this was long and all just IMO! To sum it all up: if she remains at a low GCS (coma scale ranking) for a few days, they’ll perform brain death testing and go from there.
ETA: I am so sorry about your brother.
