This document discusses coma, including its definition, causes, and approach to assessment and management. Coma is the deepest state of impaired consciousness where a patient cannot be aroused. Causes include structural brain injuries, infections, metabolic derangements, and drugs. Evaluation of a comatose patient involves assessing vital signs, neurological exam including pupil response and eye movements, investigations like blood tests and imaging, and treatment of reversible causes. Brain death is the complete and irreversible loss of brain function while cardiac and respiratory functions may be maintained artificially.