"Depends on what caused the coma," McCoy says, and this kind of talk is familiar for him, letting him go on medical autopilot for a bit, easing the stress that comes with being friends with Jim fucking Kirk. "With head trauma, it varies depending on the severity of the injury. Drug-induced comas are commonly and safely used in some surgical procedures. Jim's situation is... kinda unique. Patients exposed to that level of radiation have never survived before, and the treatment is experimental. But he is responding to treatment. We might be able to take him off oxygen in another day or two."