The patient is required to fast from food and water for 6-8 hours before anesthesia to ensure a state of gastric emptying, which can prevent the occurrence of aspiration by mistake. With the development of anesthesiology and surgery, the rapid recovery theory proposed in recent years can allow patients to fast for 6 hours and just fasting water for more than 2 hours before surgery. The main reason is that the emptying time of water in the stomach is shorter and has less impact on the patient. However, the specific preoperative water fasting time should still be based on the requirements of the anesthesia department of the hospital. In the process of induction of anesthetic drugs given to patients by anesthesiologists, in order to prevent nausea and vomiting due to anesthetic reactions, patients need to be asked to fast from water before anesthesia. Because the patient is in an unconscious state when being anesthetized, once vomiting occurs, the vomit may regurgitate in the pharynx to the trachea and enter the lungs, while the stomach contains a large amount of gastric acid, and the pH value of gastric acid is low, which is a strong acid, if it enters the trachea and lungs, causing a large amount of mucosal corrosion of the trachea and lungs, which can induce aspiration pneumonia and cause serious lung damage and infection, causing greater impact on the patient.