in a coma. A coma is defined as "profound unconsciousness" from which a person cannot be woken up. It can be caused by a variety of problems, including trauma, toxic substances, disease, and stroke. During a coma, medical staff have to take care of a patient's bowel and bladder functions, nutrition (usually through an IV), skin (see bed sores/decubitus ulcers), and possibly breathing. The longer a coma lasts, the more severe the effects will usually be.