Effects of laparotomy vs pneumoperitoneum on the hepatic catabolic stress response in ambulatory and stationary settings in pigs

Background: We recently demonstrated that laparoscopic cholecystectomy is f ollowed by a much smaller hepatic catabolic stress response than convention al cholecystectomy. It is not known what is responsible for this difference . Methods: Thirty pigs were randomly allocated to the following five treatmen t groups: (1) laparotomy, (2) pneumoperitoneum, (3) pneumoperitoneum with i nsertion of four trocars, (4) laparotomy, (5) pneumoperitoneum. Groups 1-3 were operated on in an ambulatory setting, whereas groups 4 and 5 were oper ated on in a stationary setting. Urea synthesis, as quantified by functiona l hepatic nitrogen clearance, and the response of stress hormones and cytok ines were assessed. Results: Laparotomy increased the functional hepatic nitrogen clearance by 195% (p < 0.001); pneumoperitoneum and trocars increased it by 145% (p < 0. 001); and pneumoperitoneum alone increased it by 113% (p < 0.001). The diff erence between laparotomy and both pneumoperitoneum groups was significant. If the stress factor of ambulatory surgery was eliminated, the increase in functional hepatic nitrogen clearance was reduced to 87% (p < 0.01) after laparotomy and 38% (NS) for animals subject to pneumoperitoneum. There were significant differences in concentrations of stress hormones, tumor necros is factor or, and interleukin 8 among groups intra- and postoperatively, Conclusions: The magnitude of the postoperative hepatic stress response aft er laparotomy compared to pneumoperitoneum with and without insertion of tr ocars seems to be caused by the greater trauma to the abdominal wall. Furth ermore, an ambulatory setting seems to be an important postoperative stress factor in itself.