Someone in extremis is in a desperate state, or a terrible situation — even near death. Society has made a habit of recording the final words of people in extremis — like when the dying Kane muttered "Rosebud" in "Citizen Kane."
You could say that the patients in a hospital's intensive care unit are mostly in extremis, or that when soldiers find themselves surrounded by the enemy army, they are all in extremis. This Latin phrase often means "at the point of death," and also "in an extreme situation." Literally, in extremis is "in the farthest reaches."