Preparing for surgery involves many instructions from your medical team, including fasting, often called “NPO” (nil per os), meaning “nothing by mouth.” These guidelines are fundamental for patient preparation, designed to enhance safety during anesthesia and the surgical procedure. Following these pre-operative instructions precisely is important for a smooth and safe experience.
Standard Fasting Guidelines
For most surgical procedures, specific timeframes are recommended for when you must stop eating and drinking. Solid foods should be avoided for at least 6 to 8 hours before surgery. This includes meals, chewing gum, and hard candies, as they stimulate digestive processes. Fatty, fried, or protein-rich foods may require an even longer fasting period, sometimes up to 8 hours or more, because they take longer for the stomach to digest and empty.
Clear liquids can typically be consumed up to 2 hours before the scheduled procedure. These include water, clear apple juice, black coffee or tea (without milk or cream), and carbonated beverages. This allowance for clear liquids helps maintain hydration without significantly increasing risk, as clear liquids leave the stomach quickly.
Special considerations apply to infants and young children. For breast milk, a fasting period of 4 hours is recommended before surgery, while infant formula requires a 6-hour fast. These specific timings acknowledge the different digestion rates for various types of milk and are tailored to ensure safety for younger patients.
Why Fasting is Critical
The primary reason for pre-operative fasting is to prevent pulmonary aspiration. This occurs when stomach contents are accidentally inhaled into the lungs during anesthesia. Anesthesia causes muscles to relax, including the esophageal sphincter, which normally prevents stomach contents from flowing back into the throat.
When protective reflexes like coughing and gagging are suppressed, stomach contents can enter the airway. Aspiration can lead to severe health issues, including aspiration pneumonia, lung damage, or a life-threatening lack of oxygen. An empty stomach significantly reduces the volume and acidity of any potential aspirate, lowering the risk of such complications.
Specific Considerations and Exceptions
While general fasting guidelines apply broadly, individual instructions from your medical team are important. Some essential medications, such as those for heart conditions, blood pressure, or seizures, may be permitted with a small sip of water on the morning of surgery. Confirm with your healthcare provider which medications, if any, you should take. Never take unapproved medications or supplements without specific instructions, as some, like certain blood thinners, may need to be stopped days before surgery.
Your specific medical team will provide precise instructions tailored to your individual health conditions, the type of surgery, and the anesthesia planned. Conditions such as diabetes, gastrointestinal disorders, or emergency surgeries may necessitate different fasting protocols. Follow the advice given by your surgeon and anesthesiologist, as they understand your specific needs.
Failing to adhere to the fasting instructions poses risks and may result in the delay or cancellation of your surgery. This is because an inadequately empty stomach increases the risk of aspiration, making it unsafe to administer anesthesia. Communicate openly with your medical team about your last intake of food or drink to ensure your safety and the smooth progression of your procedure.