Increased systemic inflammation after laparotomy vs laparoscopy in an animal model of peritonitis

Objective: To study the influence of laparotomy and laparoscopy on local and systemic inflammation in a rat model of peritonitis. Design: Bacteremia, peripheral leukocyte subpopulations, tumor necrosis factor alpha (TNF-alpha) plasma levels, and ex vivo secretion of peripheral blood mononuclear cells were investigated after laparotomy and laparoscopy in a prospective randomized experimental study. Setting: Surgical department of a university hospital. Animals: 60 male inbred Wistar rats. Interventions: Standardized fecal inoculum was injected intraperitoneally and rats underwent laparotomy (n=20), laparoscopy (n=20), or no further manipulation (control group, n=20). Blood samples were obtained during the perioperative course to determine bacteremia, leukocytic subpopulations, TNF-alpha plasma levels, and ex vivo secretion. The number of intraperitoneal abscesses was determined in each animal after 1 week. Main Outcome Measure: The hypothesis of the experiment was that laparoscopy with carbon dioxide leads to an increase of local and systemic inflammation in comparison with the laparotomy and control groups. Results: One hour after intervention, bacteremia was significantly higher in the laparotomy and laparoscopy groups compared with the control group (P=.01). Fecal inoculum caused significant monocytopenia and lymphocytopenia in all groups within 1 hour after intervention (P<.05), with complete recovery on day 2 only in the laparoscopy and control groups. Laparotomy caused a significant increase in TNF-alpha plasma levels and decrease of ex vivo production of TNF-alpha compared with the other 2 groups (P<.05). Conclusions: Laparotomy and laparoscopy increased the incidence of bacteremia and systemic inflammation in this peritonitis model. The inflammatory response was significantly higher in the laparotomy group compared with the laparoscopy group.