I Have A Family Member Who Overdosed On Heroin. She

I have a family member who overdosed on heroin. she has been in a coma for 4 days and has pneumonia from aspirating and heart damage. due to both of these she has had low o2 levels on her blood. Now the doctors say she had brain damage but don't know how much. She is on a vent. How long does it normally take to get over the pneumonia? and how do they evaluate brain damage in a patient who is in a coma?