The primary risk of eating before surgery is the possibility of inhaling vomit or stomach contents into one’s lungs. Normally, coughing would help to prevent a patient from inhaling vomit into his lungs. General anesthesia, however, prevents a person from coughing and allows the aspiration of vomit, which can lead to choking and a dangerous lung infection. Likewise, the use of a breathing tube during surgery prevents a flap of tissue from closing over the airway, which can lead to the inhalation of stomach contents. If a person only receives local anesthesia, however, his doctor may allow him to eat before surgery.
One of the risks of eating before surgery is aspiration vomiting. This occurs when a person’s body forms vomit while he is undergoing a surgical procedure and he then inhales the vomit into his lungs. The vomit, which is a foreign substance in the affected person’s airway, would normally be coughed out. When an individual is under the effects of general anesthesia, however, he is unable to cough and clear his airway. As a result, the patient might develop a blocked airway or a lung infection.
Another risk of eating before surgery involves the possibility of inhaling the contents of the stomach due to the inaction of a tissue flap that normally covers a person’s airway. During surgical procedures that involve the use of general anesthesia, a patient often has a breathing tube inserted into his airway. Normally, a bit of tissue covers the airway to prevent food from being inhaled when a person swallows. With the breathing tube in place, however, this tissue cannot act as it normally would. If stomach contents, including digestive fluids, back up through the esophagus, they could be inhaled into the airway.
Due to the risks of eating before surgery, it is very important that a patient follows his doctor’s instructions prior to his procedure. Often, a person is instructed to avoid eating 12 hours before the surgery or after midnight the night before surgery. This includes consumption of any type, including chewing gum, sucking on mints, and drinking beverages. Brushing teeth may also prove a concern if the patient swallows water while doing so. Instead, he is usually advised to brush his teeth but avoid swallowing any of the water.
The no-eating-before-surgery rule may not apply in all cases. For example, if a person is having a surgical procedure that only involves the use of local anesthesia, he might be allowed to eat before the surgery or be advised to consume only a light meal. This is because the anesthesia only affects the part of the body to which it is applied and should not affect the body’s ability to prevent the aspiration of food.