Conflicting Results with Use of Probiotics in Severe Acute Pancreatitis Stephen A. McClave, MD, Daren K. Heyland, MD, and Paul Wischmeyer, MD The results of the Dutch Multicenter PROPATRIA Study 1 (where use of multiple probiotics led to intestinal ischemia, increased multiple organ failure, and death) were startling enough in their own right, but were even more unexpected because they contradicted two previous studies by Olah 2,3 where use of probiotics improved outcome in severe acute pancreatitis. One has to interpret study results that the treatment itself (not an error in randomization or extraneous confounding factor) caused the negative outcome – that the addition of bacteria infused directly into the small bowel set up an adverse cascade of events that led to organ failure and ultimately death. The response to this paper however needs to be framed by the key question: With clear benefit in other critically ill patient populations and two earlier studies specifically in pancreatitis, why did this group do worse? The answer may lie in the possibility that the benefit from probiotics in pancreatitis is a bell-shaped curve – that for a variety of reasons, the group of patients in the PROPATRIA Study fell off the far side of the curve and did worse rather than better. The explanation for these poor results may be related to the high incidence of gut ischemia seen in the treatment group (where the controls appeared to have none). Investigators fed high doses of enteral nutrition (EN), fiber, and bacteria directly into the small bowel. Pancreatitis is a notorious disease process for problems with third spacing and difficulties in volume resuscitation. Six out of the nine patients who developed