Perioperative Fasting Guidelines as it relates to ERAS Protocol: Exploring Existing Modalities

Submitted by Sarah Mensa-Kwao Cook, RN, BSN

Tags: anesthesia carbohydrate-rich drinks ERAS protocol NPO perioperative Perioperative fasting

Perioperative Fasting Guidelines as it relates to ERAS Protocol: Exploring Existing Modalities

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For the longest time, any procedure requiring anesthesia was accompanied with perioperative instructions mandating a fast from midnight until the surgery. However, anyone that’s lived long enough has learned to understand that just because something has been done for a long time, it doesn’t mean it should be done for the rest of time. With technological advances and improvements in research, medical practices and patient instructions should evolve. Here, we’ll explore the rationale behind the old modality as it pertains to preoperative care and instructions, what’s changed in research and technology, and finally, what new modalities should be learned, taught, and implemented.

In the Beginning

The practice of perioperative fasting consisting of “being nil by mouth (NBM) from midnight before surgery” combined with a postoperative fast until “recovery of bowel function,” has been a mainstay in surgical realms for nearly three quarters of a century. (Lambert & Carey, 2016). How did we get here? Seventy-two years ago, Dr. Curtis Medelson (obstetrician and cardiologist) observed that a disturbing number of “women who had anesthesia in labor were vomiting and aspirating on their stomach contents during delivery.” It was reported that 0.15% of the more than 44,000 pregnancies resulted in this case. In his study, Mendelson referenced two cases where women died from this condition, aspiration pneumonitis, where undigested food blocked their airways. There were other cases where those who “aspirated liquid suffered from shortness of breath, blue discoloration [cyanosis], and a faster heartbeat than normal.” Aspiration pneumonitis occurs under general anesthetic because the laryngeal reflexes are dormant, potentially allowing the regurgitated stomach contents to draw into the lungs. Based on this study, by the 1960s, the practice of “nil by mouth” (fasting after midnight – now recognized as NPO) had become the guideline for surgical patients. (Kamenev, 2018).

What’s New?

Since the NPO guidelines had been in place, advances in technology and research have illuminated the need to adjust standard perioperative practices. As stated before, just because something’s been done for a long time, does not mean it should it be done for all time. There are two main reasons for the need of guideline adjustment: timing complications and anesthesia administration advancements.

Timing complications breaks down into three areas – midnight binge phenomena, prolonged fasting complications, and scheduling. The midnight binge phenomena are where patients (with the thought that they couldn’t consume anything until after their surgeries the following day) eat as much as they can just before midnight. The problem with this is the food “would sit in their stomachs overnight, barely digested by the time they reached operation prep early the next morning.” (HealthStatus, 2018). This defeats the point of the fast – having an empty stomach to prevent the potential aspiration. Further, since the beginning of this century, there have been nearly thirty studies revealing that patients who consumed clear liquids up to two hours before their surgeries had emptier stomachs than those who did complete fasts since the previous midnight. (HealthStatus, 2018).

Research has made it easier to understand that there are complications that come with prolonged fasting. We know that food is supposed to be our bodies’ fuel source. It begs the question, “what happens to your body while you’re starving it?” Your body must get its nutrients by breaking down itself, according to Dr. David Flum (University of Washington). We need energy to keep going during recovery, and that energy comes from glycogen (stored in the liver), which is diminished during fasting. (Bacher, 2018).

And even with this information in hand, so many hospitals still practice with the traditional NPO instructions. Scheduling played a huge role in this. The fear was that if you allowed for a patient to ingest food/drink closer to a scheduled procedure (so as to avoid the aforementioned complications), it would make them ineligible to move up in the roster if there was a need to cancel an earlier procedure. Also, it was easier to simply hand-out a blanket “everyone with surgery tomorrow must fast by midnight tonight,” than to have to figure out and assign different times for different patients. (Kamenev, 2018).

Advancements in technology and research have also shed a light on the need to change practices. For one, ether is no longer used by anesthesiologists; this is the substance that made patients feel nauseous. But probably just as important, intubation helps to “protect the airways from the aspiration of stomach contents.” (Kamenev, 2018).

New Modus Operandi

All the research and technological advancements since NPO was widely accepted as the perioperative guideline has ultimately lead to a change to the new ERAS protocols. ERAS, Enhanced Recovery after Surgery, is a multifaceted approach aimed to shorten postoperative stays through reducing stress following surgery by maintaining preoperative body/organ function through and after surgery. This ERAS protocol includes a light meal up to six hours prior to a surgical procedure, and clear fluids up to two hours before said procedure.

It is stressful enough for a patient to simply worry about the pending surgical procedure. The stress is compounded with the old way of fasting from midnight until the procedure; there is the mental stress now combined with the physical. Add this to the workout the body endures through the procedure, and it is no wonder that postoperative recovery is long (longer than it needs) and difficult. ERAS remedies this by utilizing a carbohydrate-rich liquid up until two hours prior to a procedure. “The use of carbohydrate loading attenuates postoperative insulin resistance, reduces nitrogen and protein losses, preserves skeletal muscle mass and reduces preoperative thirst, hunger and anxiety.” In addition, by helping to return postoperative bowel function quicker, this process leads to shorter stays for patients. (Melnyk, Casey, Black, & Koupparis, 2011).  This is a win all around!

Some of the leading carbohydrate-rich drinks available (i.e. clearfast, BevMD, etc.) are pretty expensive. Since the ERAS protocol has already eased the mental and physical discomforts that come with surgery, there’s a financial strain that can be eased as well. It’s already been identified that complications associated with prolonged fasting include “dehydration, hypoglycemia, and electrolyte imbalance.” (Kamenev, 2018). To counteract this, it’s been recommended to use Gatorade as a less expensive alternative than the aforementioned drinks. Gatorade is a sports drink rich in electrolytes which keeps you hydrated. It was normally recommended for after surgery, but with the new information discovered leading to the ERAS protocols, and the fact that Gatorade has a carbohydrate content of 6g/100mL, it’s now being recommended as a more accessible, readily available alternative. (Abola & Gan, 2017).


In a perfect world, costs, stress, pain and hospital stays would be nonexistent for our patients. While we are not in that perfect world, yet, we can certainly continue to make strides towards it. NPO was once the prescribed perioperative regimen. And with each technological advance and research discoveries, we draw ever closer to that elusive utopian world. The newest discovery with respect to perioperative modalities is the ERAS protocol. This new paradigm is a win for all involved. Patients no longer stress about not having anything in their system for hours before an already mentally contentious procedure. Allowing the body to have Gatorade as a substitute for carbohydrate -rich fluids up to a couple hours before a procedure also lessens the surgical complication rates (17%), reduces costs (87.5% savings), and aides in accelerating recovery. Quicker recovery leads to shorter hospital stays, which costs a lot less for the patient. These are definitely wins for the patients! The hospitals are victors as well. Those shortened stays lower the potential hospital liabilities. Further, in places where it’s been implemented, “there was a significant reduction in intravenous fluid use, complications and duration of epidural use.” And the huge win for the administrators are the overall costs that are saved (roughly $6900/patient). It’s not perfect, but it gets us closer. (Melnyk, Casey, Black, & Koupparis, 2011).

It’s been nearly three quarters of a century since NPO after midnight was initially introduced, and although it still has a place in medicine, depending on the procedure, it’s time to move to the improved modality for the vast majority of procedures and patients. While in some hospitals already, many administrators are reticent to implement these guideline changes on a full scale. The great Sam Cooke once sang, “it’s been a long time coming… a change is gonna come.” The research and technology are here now. And now is the time to make that change.


  1. Abola, R. and Gan, T. (2017). Preoperative Fasting Guidelines. Anesthesia & Analgesia, [online] 124(4), pp.1041-1043. Available at: /2017/04000/Preoperative_Fasting_Guidelines___Why_Are_We_Not.8.aspx [Accessed 23 Jul. 2018].
  2. Bacher, R. (2018). Enhanced Recovery After Surgery (ERAS) for Patients. [online] AARP Bulletin. Available at: [Accessed 23 Jul. 2018].
  3. HealthStatus. (2018). The New Rules on Eating & Drinking Before Anesthesia. [online] Available at: [Accessed 23 Jul. 2018].
  4. Kamenev, M. (2018). You Don’t Need to Do a Prolonged Fast Before Surgery. [online] Slate Magazine. Available at: examiner/2017/09/you_shouldn_t_fast_before_surgery.html [Accessed 23 Jul. 2018].
  5. Lambert, E. and Carey, S. (2016). Practice Guideline Recommendations on Perioperative Fasting. Journal of Parenteral and Enteral Nutrition, [online] 40(8), pp.1158-1165. Available at: [Accessed 23 Jul. 2018].
  6. Melnyk, M., Casey, R., Black, P. and Koupparis, A. (2011). Enhanced recovery after surgery (ERAS) protocols: Time to change practice?. Canadian Urological Association Journal, [online] pp.342-348. Available at: /PMC3202008/ [Accessed 26 Jul. 2018]