Asphyxiation is a condition of blocked transport or use of oxygen by living organisms of the body. The condition can be caused by internal factors such as breathing problems caused by respiratory diseases, or external ones such as physical strangulation or foreign substance like nitrogen gas or carbon monoxide. Asphyxiation affects tissues and organs by depriving them of vital oxygen, leading to coma or death. The term is derived from Ancient Greek words for "without" and "heartbeat".