Nutrition for the patient with severe pancreatitis

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.

The concept of "pancreatic rest"

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.

Only severe pancreatitis patients benefit from early enteral nutrition.

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:

• Keep trying with NG tube repositionining and prokinetics
• Use a "feeding protocol"
• Add TPN to meet nutritional targets (it seems some enteral feeding is still better than none)

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.

• Bizarrely, there are multiple studies supporting the commencement of nasogastric feeds within 48 hours in severe acute pacreatitis.
  • The 2009 Guidelines mention 3 meta-analysis studies, featuring combinations of 10 randomised trials. All show a mortality benefit, thought to be the result of a decreased SIRS response, which in turn is due to diminished rates of bacterial translocation from the healthier gut.
  • Change to a fat-free feed formulation
  • Change from whole protein to peptide fragments
  • Move the tube beyond the pylorus (beyond the ligament of Treitz)

ASPEN and ESPEN guidelines for severe acute pancreatitis

The ASPEN guidelines (2009) and the ESPEN guidelines (2002) were used to create a comparison of guidelines:

The ESPEN statement is about 13 years old at the time of writing. Its recommendations include the following:

• For mild or moderate pancreatitis:
  • "There is no evidence that either enteral or parenteral nutrition has a beneficial effect on clinical outcome"
• For severe pancreatitis:
  • Enteral feeding should be attempted in all patients
  • Nutritional requirements should be:
    • 25-35 kcal/kg of total body weight per day
    • 1.2 to 1.5g/kg of protein
    • 3-6g/kg of carbohydrate
    • go easy on the lipiuds (up to 2g/kg)
  • Start feeding via a jejunal tube (remember, this is a 2002 statement)
  • If enteral nutrition is poorly tolerated and caloric goals are not being achieved, add some TPN but keep going with small-volume or elemental enteral feeding

The ASPEN statement is a more recent 2009 product. Its recommendations include the following:

• For mild or moderate pancreatitis:
  • It is safe to fast these people for up to 7 days! They "... do not require nutrition support therapy (unless ... there is failure to advance to oral diet within 7 days)" - pp. 207
• For severe pancreatitis:
  • Enteral (nasogastric) feeding should commence as soon as initial resuscitation is complete.
  • Feed tolerance may be enhanced by the following measures:
    • Early enteral nutrition (to minimise ileus)
    • Pushing the NGT distally (into the jejunum) -  it doesn't seem to matter in terms of pain or pancreatitis severity, but feed tolerance may improve
    • Changing to elemental feeds (small peptides, medium-chain triglycerides)
    • Using continuous infusion rather than bolus feeding
  • TPN should not be initiated until after you have made a solid attempt with enteral nutrition for at least 5 days, i.e. when it is obvious that there is profound enteral feed intolerance in spite of various "tolerance-enhancing " measures.

Official position of the CICM examiners

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.

• For mild or moderate pancreatitis:
  • Fast for the first 3-4 days? Oh's Manual suggests that these patients need no feeding whatsoever until the disease settles (i.e. for 5-7 days), but the 2017 college answer recommends immediate feeding. The college quote a study ("NEJM 2014") to support their answer, which presumably is the PYTHON trial by Bakker et al (2014). This was an RCT which compared immediate enteral feeding with oral diet initiated 72 hours after presentation, which is not exactly "commence at admission or within 24 hours" ​​​​​.​
  • Advance to normal oral diet before 72 hours. Bakker et al (2014) found that enteral nutrition is no better than oral.
  • No need to rush enteral nutrition. Only progress to enteral nutrition of the patient is not tolerating oral diet after 5-7 days
  • Avoid TPN. Only progress to TPN if enteral nutrition has been trialled and is clearly not tolerated. The college mention another study ("Cochrane 2010") to support their avrsion to TPN,  presumably referring to the meta-analysis by Al-Omran et al (2010). After pruning the evidence tree the authors found only two trials to analyse, with a total of 70 patients. They were forced to conclude that the data were insufficient for any firm recommendation, but that the trend was in the direction of better outcomes with enteral nutrition. This vaguely reflects "reduced mortality and other end-points (including infective, MOF)" which is what the college examiners said about it.
• For severe pancreatitis:
  • EN is preferable to PN (ASPEN and ESPEN agree on this)
  • EN should be started early.
  • Tube position does not matter (gastric vs jejunal). The college refer to "2 small metaanalyses" in support of their assertion, presumably referring to Chang et al (2013)  with 157 patients and Petrov et al (2008) with 92 patients.  Neither found any benefit in jejunal feeding unless you've got clearly demonstrated impaired gastric emptying. 
  • Elemental feeds are preferred (ASPEN)
  • Nutritional requirements should be:
    • 25-35 kcal/kg of total body weight per day
    • 1.2 to 1.5g/kg of protein
    • 3-6g/kg of carbohydrate
    • go easy on the lipids (up to 2g/kg)
  • When to use parentral nutrition? These guidelines are much less prescriptive than previous statements. "when EN is contraindicated or not well tolerated", they say.