In the practice of the clinician, we are faced, essentially, with two clinical circumstances. If, on the basis of the symptoms with which a person presents to the Emergency Department (or is brought in by the Emergency Department), we can presume that we are dealing with an illness that will immediately lead to his death, we must intervene immediately. We should ascertain the cause of the patient's condition as quickly as possible and then implement either pharmacological or surgical treatment. In such circumstances, we speak of an emergency.