This issue has come up in Question 25 from the second paper of 2014 and Question 16 from the second paper of 2017. In general, wherever pancreatitis appears in vivas or in hot cases, nutrition is asked about. This chapter is a summary of the ASPEN and ESPEN guidlines for severe acute pancreatitis. In short, the population of severe pancreatitis patients benefits from early enteral nutrition, whereas for the mild cases there is no specific evidence to guide you (there does not seem to be a difference in outcome, whatever you do with their nutrition). If the pancreatitis is not "severe" by the Atlanta definition, all nutritional therapy may be safely withheld for about a week.
There is an excellent recent review of nutrition in severe acute pancreatitis, which discusses these issues in lucid detail. Early studies suggested (correctly) that jejunal administration of food will bypass the cells that secrete cholecystokinin, and thus prevent pancreatic exocrine secretion. This gave rise to the impression that the pancreas can be "rested" and further autodigestive damage averted. There may or may not be such an effect, but it has not been well studied. However, the mild pancreatitis patients don't need to be fed for the first few days, and this means the whole question can be avoided. One can wait for the pancreatitis to improve, and start feeding them 5-7 days after admission. For the very severe patients (i.e. those who one expects to be critically ill for many days) enteral nutrition should be commenced early.
If the pancreatitis is not "severe" by the Atlanta definition, all nutritional therapy may be safely withheld for about a week. It is apparently safe to starve these mildly-moderately severe pancreatitis patients. If they fail to progress to oral diet within the week, then one may consider some form of nutritional support.
If the feeds are not tolerated, one may take the following steps:
If the feeds are still not tolerated, one may change over completely to TPN... but it is better to wait until day 5 or later.
Additionally... the standard surgical practice of feeding these people with nasojejunal tubes rather than nasogastric tubes (to "rest" the pancreas) does not appear to be supported by evidence. The counter-argument to nasojejunal feeding is that the necrotic pancreas is probably not very responsive to the normal secretory stimuli, and will not become more necrotic if the nearby duodenum is exposed to some sort of nutritional supplement.
The ESPEN statement is about 13 years old at the time of writing. Its recommendations include the following:
The ASPEN statement is a more recent 2009 product. Its recommendations include the following:
The answer to Question 25 from the second paper of 2014 contains the abovelisted guidelines as a table of comparison, contrasting the ASPEN and ESPEN positions. Apart from these elderly papers, we can also turn to the 2012 "International consensus guidelines for nutrition therapy in pancreatitis", quoted in Oh's Manual. Additional insight into what the examiners expect (and who's been reading which literature) can be derived from the college answer to Question 16 from the second paper of 2017.
In summary, these sources can be remixed into the following list of recommendations, which the time-poor candidate can use as a tl;dr shortcut to a passing mark.