How long should I fast before general anesthesia surgery?

When we watch TV dramas, we often see that family members of patients who are about to undergo surgery are told by doctors or nurses that the patients cannot eat or drink before the operation. However, people do not understand why this cannot be done before the operation. People believe that they should eat more nutritious foods before the operation to increase their resistance. How long should I fast before general anesthesia surgery? Let’s learn about it together below.

The stimulation during surgery will weaken our gastrointestinal function , and the food we eat will not be easily digested and will be stored in the gastrointestinal tract. After anesthesia, a person's consciousness and cough reflex will temporarily disappear, and the person will easily become nauseous and vomit. Generally speaking, after we vomit, the epiglottis will cover the entrance of the trachea like a small lid, making it difficult for vomit to enter the trachea. Under anesthesia, this physiological reaction will weaken or even disappear. This allows the vomitus to pass smoothly into the trachea and lungs.

Because there is a large amount of gastrointestinal fluid in our gastrointestinal tract , these fluids are strongly acidic or alkaline. When vomitus enters the trachea, these fluids go along the trachea into the lungs, causing chemical damage to the lungs. After the lungs are damaged, they cannot open. Even if gas reaches the lungs through the trachea, it cannot be exchanged with the blood. The human body is deprived of oxygen, causing necrosis of tissues and organs.

Once reflux aspiration occurs, rescue is very difficult. Even if emergency measures are taken to save lives, almost 100% of patients will suffer brain damage because the brain is extremely sensitive to lack of oxygen.

Therefore, you cannot eat or drink after 21:00 the night before the operation or on the morning of the operation. Even if the surgery does not start in the morning, you cannot eat or drink. Some people may ask, what if you are not allowed to eat or drink for such a long time and you become extremely hungry? We can tell the attending physician, who will prescribe some glucose infusion instead of food to relieve hunger.