Many people about to undergo a surgical procedure are surprised to learn that they are not allowed to eat or drink anything after midnight on the day of their procedure. Certain risks are associated with having solids or fluids in the stomach during anesthesia. Because many people undergo surgery at some point in their lives, it is important to understand why preoperative fasting is necessary for safety reasons.
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Preventing Anesthesia Complications
Fasting is most important for general anesthesia, a type of anesthesia that results in complete loss of consciousness and requires a breathing tube for mechanical ventilation. Not fasting before general anesthesia is administered poses a risk of inhalation of the stomach contents into the lungs. This is known as pulmonary aspiration. It can occur while under anesthesia because the body's protective mechanisms that prevent food from entering the lungs are inhibited. If stomach contents are inhaled, suffocation can result. Stomach acid can also damage the lungs, resulting in a particularly severe type of pneumonia.
If instructions are forgotten and food or liquids are taken, the anesthesiologist and surgeon should be notified immediately. The procedure may be delayed until the stomach has emptied. Because many people take daily medications in the morning, the surgeon should be asked whether to take them on the morning of the procedure.