Anesthesia is administered under optimal conditions for surgery. A pre-anesthesia check is done prior to administration of anesthesia. Drugs used in anesthesia are called as anesthetics. There are major and minor risks in administering anesthesia such as pulmonary embolism, post-operative nausea and vomiting. The anesthetist chooses and determines the dosage of one or more drugs to achieve the types and degree of anesthesia appropriate to the type of procedure carried on and the particular patient.