Randomized clinical trial of the effects of immediate enteral nutrition on metabolic responses to major colorectal surgery in an enhanced recovery protocol

Background: The effects of immediate postoperative enteral nutrition on postoperative nitrogen balance and insulin resistance were studied in patients subjected to an enhanced-recovery protocol. Methods: Eighteen patients undergoing major colorectal surgery in an enhanced-recovery protocol were randomized to immediate postoperative enteral feeding for 4 days with either complete or hypocaloric nutrition. Nitrogen balance and changes in glucose kinetics, substrate utilization (indirect calorimetry) and insulin sensitivity (hyperinsulinaemic-euglycaemic clamp) were measured. Values are mean(s.e.m.). Results: Mean postoperative urinary nitrogen losses were low (10-7(1-0) versus 10.5(0.7) g per day for complete versus hypocaloric nutrition) and insulin resistance was insignificant (-20(7) versus - 27(11) per cent), with no difference between groups. Complete enteral feeding was given without hyperglycaemia (blood glucose concentration 5.8(0.4) versus 5.0(0.4) mmol/1) and resulted in nitrogen balance (+ 0.1(0-8) versus - 12.6(0.6) g nitrogen per day; P < 0.001). Conclusion: This enhanced-recovery protocol was associated with minimal postoperative insulin resistance and nitrogen losses after surgery. Immediate postoperative enteral nutrition was provided without hyperglycaernia and resulted in nitrogen balance.