once oxygen is returned to a damaged heart reperfusion injury occurs as a result of
Reperfusion injury Reperfusion injury or reperfusion insult, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue (re- + perfusion) after a period of ischemia or lack of oxygen (anoxia or hypoxia). The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than (or along with) restoration of normal function.
Mouth-to-mouth resuscitation Mouth-to-mouth resuscitation, a form of artificial ventilation, is the act of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body, where a rescuer presses his or her mouth against that of the victim and blows air into the person's lungs.[1][2] Assistance takes many forms, but generally entails providing air for a person who is not breathing or is not making sufficient respiratory effort on his/her own.[3] It is used on a patient with a beating heart or as part of cardiopulmonary resuscitation (CPR) to achieve the internal respiration).