BIL is home. The doctors have no answers. They accuse him of not taking his bipolar meds, despite the fact that (1) Sister saw him take them the morning he passed out and (2) they gave him the meds in the hospital - yet he has zero levels in his system. So then they say maybe he metabolizes things quickly. Their other explanation is a seizure, but he's on anti-seizure meds for anxiety. Or a heart attack. Or anxiety.
So the good news is that he was released and his home, albeit with a heart monitor. Bad news is no answers. My sister is getting him in with a different practice that has a team approach - psychiatrist, cardiologist and neurologist.
Thanks for everyone's prayers and thoughts.