BACKGROUND: We recently demonstrated that laparoscopic cholecystectomy is followed by a much smaller hepatic catabolic stress response than conventional cholecystectomy. It is not known what is responsible for this difference. METHODS: Thirty pigs were randomly allocated to the following five treatment groups: (1) laparotomy, (2) pneumoperitoneum, (3) pneumoperitoneum with insertion of four trocars, (4) laparotomy, (5) pneumoperitoneum. Groups 1-3 were operated on in an ambulatory setting, whereas groups 4 and 5 were operated on in a stationary setting. Urea synthesis, as quantified by functional hepatic nitrogen clearance, and the response of stress hormones and cytokines 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 difference 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 necrosis factor alpha, and interleukin 8 among groups intra- and postoperatively. CONCLUSIONS: The magnitude of the postoperative hepatic stress response after laparotomy compared to pneumoperitoneum with and without insertion of trocars seems to be caused by the greater trauma to the abdominal wall. Furthermore, an ambulatory setting seems to be an important postoperative stress factor in itself.
BACKGROUND: We recently demonstrated that laparoscopic cholecystectomy is followed by a much smaller hepatic catabolic stress response than conventional cholecystectomy. It is not known what is responsible for this difference. METHODS: Thirty pigs were randomly allocated to the following five treatment groups: (1) laparotomy, (2) pneumoperitoneum, (3) pneumoperitoneum with insertion of four trocars, (4) laparotomy, (5) pneumoperitoneum. Groups 1-3 were operated on in an ambulatory setting, whereas groups 4 and 5 were operated on in a stationary setting. Urea synthesis, as quantified by functional hepatic nitrogen clearance, and the response of stress hormones and cytokines 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 difference 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 necrosis factor alpha, and interleukin 8 among groups intra- and postoperatively. CONCLUSIONS: The magnitude of the postoperative hepatic stress response after laparotomy compared to pneumoperitoneum with and without insertion of trocars seems to be caused by the greater trauma to the abdominal wall. Furthermore, an ambulatory setting seems to be an important postoperative stress factor in itself.