Patients scheduled for surgery must refrain from eating or drinking for a period beforehand. This fundamental safety measure prevents serious complications during the procedure. Adhering to these guidelines promotes patient well-being.
The Primary Risk: Aspiration
The main reason for fasting before surgery is to prevent pulmonary aspiration. Aspiration occurs when stomach contents enter the lungs, often during anesthesia when protective reflexes are suppressed. This can lead to severe health issues.
A significant complication is aspiration pneumonia, an inflammation of the lungs caused by foreign material. This condition can result in lung damage, breathing difficulties, and a prolonged, potentially life-threatening recovery.
How Anesthesia Affects Your Body
General anesthesia alters the body’s functions, suppressing protective reflexes like coughing, gagging, and swallowing. These reflexes prevent stomach contents from entering the lungs.
Anesthesia also relaxes muscles, including esophageal sphincters that act as barriers between the stomach and esophagus. When relaxed, stomach contents can reflux, increasing aspiration risk if protective reflexes are absent. This combination of relaxed muscles and suppressed reflexes creates heightened vulnerability under anesthesia if the stomach is not empty.
Specific Fasting Guidelines
Medical professionals issue specific fasting guidelines, often using the term NPO, which stands for “nil per os,” meaning “nothing by mouth.” These guidelines specify the minimum time periods a patient must fast before surgery, depending on the type of substance. For clear liquids, such as water, clear apple juice without pulp, black coffee, or clear tea without milk, a fasting period of at least two hours is generally recommended for adults and children.
For breast milk, the typical fasting period is four hours, while infant formula and non-human milk usually require a six-hour fast. Solid foods, including light meals, generally require a fasting period of at least six hours. Fatty or fried foods, or heavy meals, may necessitate an even longer fasting period, often eight hours or more, due to their slower digestion time. These specific instructions are tailored by the medical team based on the patient’s age, the type of surgery, and individual health conditions.
Consequences of Not Following Instructions
Failing to follow preoperative fasting instructions can have consequences, most commonly the delay or cancellation of surgery. This decision prioritizes patient safety, as proceeding with a non-fasted patient significantly increases the risk of aspiration and its associated complications.
Honesty with the medical team is important if an accidental intake of food or drink occurs. Informing them allows assessment and an informed decision regarding the safest course of action, even if it means rescheduling the procedure. The adherence to these guidelines is an important component of safe surgical care.