Moving beyond the 'pancreatic rest' in severe and critical acute pancreatitis

Nasojejunal tube feeding is considered the current standard of care in patients with severe and critical acute pancreatitis. However, it is not known whether enteral nutrition is best delivered into the jejunum. This Commentary discusses recent clinical studies that have shown that tube feeding into the stomach is safe and well tolerated in the vast majority of patients with acute pancreatitis, thus overthrowing the notion of putting the pancreas at rest. Development of a new conceptual framework is warranted to further advance nutritional management of patients with acute pancreatitis.

Enteral nutrition is a rapidly evolving frontier in the management of acute pancreatitis (AP). In the previous issue of Critical Care, Chang and colleagues investigate whether nasojejunal tube feeding confers any tangible benefi t compared with nasogastric tube feeding in patients with AP [1]. It has been 5 years since publication of the pre vious systematic review on the topic [2] and it is timely to review the progress. Further, the recent international multidisciplinary classifi cation of AP has redefi ned the 'severe' category of severity and introduced the new 'critical' category of severity (Table 1), thus putting a high emphasis on the need to optimise manage ment of these most challenging patients [3][4][5][6].
e study by Chang and colleagues [1] adds an important perspective to the discussion regarding the 'pancreatic rest' concept, which is perhaps the oldest dogma in the management of AP. e central tenet of this concept is that enteral nutrition delivered into any part of the upper gastrointestinal tract other than the jejunum stimulates pancreatic secretion and, consequently, exacerbates the severity of AP. e corollary is that 'non-stimulatory' nutrition had been widely advocated, being total parenteral nutrition two to three decades ago and nasojejunal tube feeding in the past decade. at is why the majority of randomised controlled trials in the past studied 'non-stimulatory' regimens as both intervention and comparator, that is, either parenteral nutrition versus nil per os, or parenteral nutrition versus jejunal tube feeding, or jejunal tube feeding versus nil per os [7,8]. It is argued that this has retarded progress in the fi eld. e systematic literature review by Chang and colleagues [1] has appraised the current best evidence regarding the use of nasogastric tube feeding (presumed to be 'stimulatory') in patients with AP. It demonstrates that the evidence base is (still) relatively small but does show that enteral nutrition given via the nasogastric route is well tolerated in more than 90% of patients with AP [9][10][11]. In line with the previous systematic review [2], it shows no statistically signifi cant diff erence between 'non-stimulatory' and 'stimulatory' regimens in terms of morbidity and mortality. e new, and somewhat surprising, fi nding here is that both routes of enteral feeding appear to be equivalent in terms of delivery of target calories.
ere are two possible explanations for the observed results. First, tube feeding into the stomach might have been 'non-stimulatory' in patients with AP. Unfortunately, little is known about the secretory response of the pancreas during the acute phase of clinical AP, let alone the eff ect of feeding on it [12]. But a study in healthy volunteers demonstrated that both oral and duodenal tube feeding stimulate pancreatic enzyme secretion in comparison with placebo [13]. Moreover, the degree of pancreatic stimulation is very similar between oral and duodenal tube feeding. Second, tube feeding into the stomach might have stimulated the pancreas in patients with AP but it has no clinical ramifi cations, essentially meaning that the concept of 'pancreatic rest' might have been fallacious. Although it has become deeply entrenched in the management of AP, it is worth noting that the 'pancreatic rest' concept was never proven in randomised controlled trials. Moreover, the recent MIMOSA (MIld to MOderate acute pancreatitis: early Abstract Nasojejunal tube feeding is considered the current standard of care in patients with severe and critical acute pancreatitis. However, it is not known whether enteral nutrition is best delivered into the jejunum. This Commentary discusses recent clinical studies that have shown that tube feeding into the stomach is safe and well tolerated in the vast majority of patients with acute pancreatitis, thus overthrowing the notion of putting the pancreas at rest. Development of a new conceptual framework is warranted to further advance nutritional management of patients with acute pancreatitis. naSogastric tube feeding compared with pAncreatic rest) trial compared in a randomized fashion early nasogastric tube feeding (commenced within 24 hours after hospital admission) with nil per os and found that nasogasric feeding does not exacerbate the course of AP and even reduces the risk of oral food intolerance [14]. Similarly, an earlier randomised controlled trial compared early nasogastric tube feeding (commenced within 24 hours after hospital admission) with parenteral nutrition and found no diff erence between 'non-stimulatory' and 'stimulatory' regimens [15].
In conclusion, accumulating evidence indicates that the site of enteral tube feeding does not aff ect major clinical outcomes in patients with AP. Given that tube feeding into the stomach is more practical than into the jejunum in the majority of clinical settings, it should be considered as the fi rst-line approach for patients with severe and critical AP. e 'pancreatic rest' concept can now be put to rest. ere is a need and justifi cation for developing a contemporary conceptual framework concerning nutritional management of AP.

Competing interests
The author declares that he has no competing interests.  (Peri)pancreatic necrosis is nonviable tissue located in the pancreas alone, or in the pancreas and peripancreatic tissues, or in peripancreatic tissues alone. It can be solid or semisolid (partially lique ed) and is without a radiologically de ned wall. Sterile (peri)pancreatic necrosis is the absence of proven infection in necrosis. Infected (peri)pancreatic necrosis is de ned when at least one of the following is present: gas bubbles within (peri)pancreatic necrosis on computed tomography; a positive culture of (peri)pancreatic necrosis obtained by image guided ne-needle aspiration; a positive culture of (peri)pancreatic necrosis obtained during the rst drainage and/or necrosectomy. Organ failure is de ned for three organ systems (cardiovascular, renal, and respiratory) on the basis of the worst measurement over a 24-hour period. In patients without pre-existing organ dysfunction, organ failure is de ned as either a score of 2 or more in the assessed organ system using the SOFA (Sepsis-related Organ Failure Assessment) score or when the relevant threshold is breached, as shown: Cardiovascular, need for inotropic agent; Renal, creatinine ≥171 μmol/L (≥2.0 mg/dl); Respiratory, PaO 2 /FiO 2 (partial pressure of oxygen/fractional inspired oxygen concentration) ≤300 mmHg (≤40 kPa). Persistent organ failure is the evidence of organ failure in the same organ system for 48 hours or more. Transient organ failure is the evidence of organ failure in the same organ system for less than 48 hours.