A definition of death based on the absolute and total loss of the individual's brain function that is irreversible. This definition of death is a medical definition which may differ from religious, ethical, philosophical or cultural definitions of death. Modern anesthesia techniques can render a person without brain activities (flat EEG), totally paralyzed (with neuromuscular blocking agents), and with no cardiac (heart) activity (with cardioplegic solutions), such as is the case when a patient is undergoing extracorporeal circulation during cardiac anesthesia. In this case, despite that the patient physically resembles that of a dead person, the condition is reversible. Therefore, to declare brain death, one must follow a protocol of clinical testing as well as preclude anesthetic causes and hypothermia.