REVERSAL BY SHORT-CHAIN FATTY-ACIDS OF COLONIC FLUID SECRETION INDUCED BY ENTERAL FEEDING

Diarrhoea complicates enteral feeding in up to 25% of patients. In-viv o perfusion studies in healthy subjects have shown secretion of salt a nd water in the ascending colon in response to enteral feeding. This s tudy investigated the effect of short-chain fatty acids (SCFA) on this secretory response. Six healthy volunteers underwent segmental in-viv o colonic perfusion. First, baseline fasting colonic water and electro lyte movement was established, then a standard polymeric enteral diet was infused into the stomach while the colon was perfused with either a control electrolyte solution or a test solution containing SCFA. The electrolyte concentrations and osmolality of the two perfusates were identical. In the fasting state water was absorbed throughout the colo n. During the control infusion there was significant (p < 0.05) secret ion of water in the ascending colon (median rate 1.0 mL per min [95% C I 2.8 mL per min secretion to 0.8 mL per min absorption]). During the SCFA infusion the secretion was significantly reversed (p < 0.05) and there was net absorption (1.6 [0.8-3.7] mL per min). In the distal col on water absorption was significantly greater during the control infus ion than during fasting (3.7 [2.5-4.6] vs 1.3 [0.3-2.2] mL per min); d uring the test infusion this absorption persisted (2.8 [1.3-3.6] mL pe r min). Movement of sodium, chloride, and potassium ions was similar t o that of water in all stages of the study. Bicarbonate movement did n ot significantly change at any stage. Infusion of SCFA directly into t he caecum reverses the fluid secretion seen in the ascending colon dur ing enteral feeding. This finding could have implications for the mana gement of diarrhoea related to enteral feeding.