Your eating and breathing passageways both originate at the back of the throat. While awake, your gag refluxes protect your airways from being exposed to food and stomach acid. However, when you are asleep and the gag reflex is inactive, there is a possibility you could regurgitate your stomach contents and they could enter your trachea or lungs. To avoid this complication, it is important to fast before surgery without becoming dehydrated prior to the day of your surgery/procedure.