Not being conscious. When a person becomes or appears to be unconscious, they appear to be in a sleep-like unresponsive state, where all muscles become relaxed and 'floppy'. This creates a danger to the patient's life, as their tongue (a muscle) rolls to the back of the throat, and blocks the airway. Also, as the patient regains consciousness, their stomach wall contracts, causing the contents of their bowels to be forced up the oesophagus where it would enter the mouth to be drained, but because the tongue is blocking it's way, a sufficient amount of vomit enters the lungs, and the patient therefore drowns on their own sick.
To prevent this, simply check the patient's airway and breathing. If they are breathing, place them into the recovery position. If not, seek help immediately and make sure someome trained in first aid is present to perform CPR until paramedics arrive.
Unconsciousness - (noun) 1.The state of lacking consciousness, of being unconscious.
2.Ignorance or innocence; the state of being uninformed or unaware.