1. Asphyxiation of an organism (having breathing stopped) as a result of its own metabolism.
2. A cessation or failure of the respiratory process (breathing) as a result of internal metabolic activities.

The term metabolism refers to the entire physical and chemical processes involved in the maintenance and reproduction of life in which nutrients are broken down to generate energy and to give simpler molecules (catabolism) which by themselves may be used to form more complex molecules (anabolism) and it also consists of all of the physical and chemical changes that occur in cells to allow growth and to maintain body functions as food is converted into the energy and the products needed to sustain life.