Patients are basically not allowed to eat the day before a typical surgery, and are kept off water for 6-8 hours before surgery, sometimes requiring bowel cleansing. Why is food not allowed? First of all, if water fasting is not prohibited before surgery and the patient is still eating 1-2 hours before surgery, then the food in the stomach does not enter the small intestine immediately. The gastric emptying time is related to the type of food eaten. If the food is purely sugary, it usually takes about 2 hours to empty, protein-based food, about 3-4 hours, and pure fat-based food, about 5-6 hours. Therefore, the average mixed food is 4-5 hours, and the rate of stomach emptying is also proportional to the amount of food eaten. If you eat 6 hours before surgery, it is likely that a large amount of food will remain in your stomach at the time of surgery. It is easy for stomach contents to reflux into the esophagus during anesthesia, and it is easy to aspirate into the lungs causing aspiration, which can lead to serious and life-threatening consequences. Why is it easy to aspirate after anesthesia? The effect of anesthetic drugs on the function of the esophagogastric sphincter, such as anticholinergic drugs, atropine and scopolamine have a relaxing effect on the sphincter, while narcotic analgesics such as morphine and pethidine can reduce the pressure of the sphincter. Succinylcholine increases the intragastric pressure through myofibrillation, and food and gastric juice easily reflux into the esophagus. In addition, airway obstruction occurs during induction of anesthesia, and a significant decrease in intrathoracic pressure during forceful inspiration, coupled with the effect of gravity in head-down position and other positions, can also lead to gastric content reflux. Furthermore, after the application of inotropic drugs in anesthesia, and then when the mask is pressurized to administer oxygen, gas enters the possible stomach, and anesthesia and surgery can also weaken the peristalsis of the gastrointestinal tract, and a large amount of air and gastric juice accumulates in the stomach, and the tension of the gastrointestinal tract decreases, making it easier for gastric contents to into the esophagus and the aspiration tract. The risk of accidental aspiration? The consequences are serious. It can lead to aspiration pneumonia, which is characterized by dyspnea, shortness of breath, diffuse rales and wet rales in both lungs. Severe lung damage caused by aspiration of small amounts of acid into the lungs. For acute aspiration pulmonary edema caused by intra-tracheal aspiration of low-acid gastric fluid (pH < 2.5), presenting with acute asthma-like attacks, marked cyanosis, and even causing death is called Mendelson syndrome. It can lead to laryngeal and tracheal spasms, a drop in blood pressure, and even cardiac arrest. If the amount of inhalation is large, it leads to acute whistle failure and is often difficult to resuscitate successfully. Another reason for not allowing preoperative food: gastrointestinal surgery is strictly fasting, generally the day before surgery fasting, while performing intestinal preparation, which generally means drinking laxatives and completely emptying the gastrointestinal tract. The purpose, in addition to the above-mentioned anesthesia safety, is for the safety of the surgery and a smooth recovery later. Why do you say so? Because the gastrointestinal tract surgery, after the removal of part of the digestive tract reconstruction, is the gastrointestinal or intestinal anastomosis (in common parlance is reattached together), if not emptying the intestinal tract, just connected to the digestive tract, will be contaminated by gastrointestinal contents, or even direct contamination of stool, easy to cause poor healing of the anastomosis, non-healing, gastrointestinal stuff into the abdominal cavity, causing abdominal infection, fever, abdominal pain, almost inevitable secondary surgery is performed. Of course, some minor surgery, common local anesthesia surgery, is generally not required to fast. Therefore, you must listen to the doctor before major surgery and do a strict fast. Stealing food, the ultimate loss is their own, I think no one will play with life or as a child's play.