Understanding Pre-Anesthesia Dietary Restrictions

September 29, 2020
A medical professional helps prepare a patient ahead of surgery

As modern science and technology has allowed for longer and more complicated surgical procedures to treat increasingly complex medical problems, a need for stronger anesthetics has emerged in parallel. Many operative procedures are likely accompanied by local or general anesthesia [1]. Local anesthesia numbs only the area of treatment and, unless the procedure involves the digestive system or bladder, does not call for preoperative dietary restrictions [1]. General anesthesia, which is usually delivered via a combination of intravenous drugs and inhaled gases, puts the patient in an unconscious state in which the body is unable to regulate as normal and does require preoperative preparations [4]. 

Since the anesthetized brain is unable to respond to pain signals with safety reflexes, an anesthesia provider is required throughout the procedure to monitor the patient’s vital signs and manage their breathing [4]. The anesthesia provider at the surgery is often the final physician to confirm patient readiness for the procedure [5]. For procedures that take significant time to complete, cause significant blood loss, must be performed in a cold environment, or affect breathing patterns, perfecting a routine for before and during the operation is crucial to a patient’s survival [4].  

One important risk with general anesthesia is the possibility of aspiration, in which stomach contents are expelled into the esophagus and lungs [5]. This can happen if the patient vomits during the operation while under anesthesia, which is one of the most common complications of surgery if there is food in a patient’s stomach [3]. The endotracheal tube that is used for intubation and breathing assistance both increases the risk of aspiration and acts as another obstacle for medical staff in remedying the aspiration [3]. With the anesthesia paralyzing the patient’s body and inhibiting bodily reflexes and the intubation tube blocking access, the patient could easily inhale vomit into their lungs and choke [3]. Aspiration can lead to further complications such as aspiration pneumonia or serious lung damage [3][1]. 

In addition to not taking certain medications preoperatively that may complicate the procedure such as blood thinners or aspirin, the most effective way to prevent surgical complications is to ensure the patient’s stomach is empty of foods and fluids during the operation [4]. The patient’s responsibility is to prepare their body by fasting immediately before the operation, according to guidelines provided by their surgical team [2]. Fasting regulations vary by procedure, age group, and patient, but some universal guidelines are generally set in place [2]. 

Most patients above the age of twelve years old are required to stop consuming solid foods, dairy, and alcohol up until eight hours before their scheduled time of arrival to the hospital and encouraged to drink clear liquids such as apple juice or certain electrolyte-replenishing drinks up until two hours before their scheduled time of arrival [2]. As the age group decreases to children ages three to twelve, the same dietary restrictions are applied to eight hours and two hours before the scheduled time of the procedure [2]. Babies, toddlers, and infants are allowed milk, formula, and breast milk up until four to six hours of the procedure time in addition to the normal child regulations [2]. 

Other pre-anesthesia dietary restrictions for the days leading up to the procedure include taking lean, protein-rich foods to aid in healing post-surgery and staying hydrated to prevent bouts of thirst during the fast [3]. Consuming an exceptionally large last meal before the fast is also discouraged, as it will take longer to digest and negates the purpose of fasting in the following hours [3]. Finally, for patients taking medications, their surgeons may or may not grant them permission to take the medications in the morning accompanied by small sips of water [3]. 

These regulations, although strict, are put in place to reduce the risks of surgery and ensure patient safety. In cases which the patient does eat or drink, a backup option for urgent surgeries, although not preferred to fasting, is to conduct a bowel preparation to remove food and stool from the digestive tract [3]. Ultimately, it is in the best interest of the patient undergoing the procedure to follow the preoperative guidelines set in place by their surgeons and physicians to improve their chances of a smooth and successful surgical experience. 


[1]  Can I eat or drink before an operation? (2020, May 1). Retrieved September 28, 2020, from https://www.nhs.uk/common-health-questions/operations-tests-and-procedures/can-i-eat-or-drink-before-an-operation/ 

[2] When to Stop Eating and Drinking. (n.d.). Retrieved September 28, 2020, from https://www.uclahealth.org/anes/fasting-guidelines 

[3] Whitlock, J. (2019, December 2). Why You Can’t Eat or Drink Before Surgery. Retrieved September 28, 2020, from https://www.verywellhealth.com/why-cant-i-eat-or-drink-before-surgery-3157000 

[4] Mayo Clinic Staff. (2018, December 04). General anesthesia. Retrieved September 28, 2020, from https://www.mayoclinic.org/tests-procedures/anesthesia/about/pac-20384568 

[5] Why Can’t I Eat or Drink the Night Before Surgery? (2016, December 21). Retrieved September 28, 2020, from https://health.mountsinai.org/blog/why-cant-i-eat-or-drink-the-night-before-surgery/