Purpose: To develop an animal model to assess the stress response to open laparoscopic surgery. Such a model would allow objective physiologic assessment of the putative benefits of laparoscopy provide a framework in which to compare modifications in operative anesthetic technique that might decrease the stress of surgery. Materials Methods: Mongrel dogs underwent laparoscopic (N = 12) or open surgical (N = 12) left nephrectomy. In 11 control animals after induction of anesthesia line placement the animal underwent either no intervention (open surgery sham; N = 6) or pneumoperitoneum only (laparoscopic sham; N = 5). Serum glucose cortisol were measured preoperatively at skin closure at 4 8 24 hours postoperatively. Values at each time point were compared in the laparoscopic open surgical nephrectomy groups in each of the two nephrectomy groups their respective shams. Results: Compared with baseline there was a sharp rise in serum cortisol at the time of skin closure with a gradual decline to baseline values by 24 hours in all experimental animals. Significantly lower serum cortisol concentrations were seen at 4 8 hours postoperatively in the laparoscopic group than in the open surgery group. Cortisol was significantly higher in the open group than in the sham-open group at all time points whereas cortisol was greater in the laparoscopic group than in the pneumoperitoneum-only group only at the 4-hour time point. No differences were seen in serum glucose between groups. Conclusions: The serum cortisol concentration appears to be a good measure of surgical stress in the canine model. The rapid decline in serum cortisol after laparoscopy compared with open surgery may indicate a lesser degree or quicker resolution of surgical stress in the former. Furthermore the similarity in cortisol curves between laparoscopy pneumoperitoneum only suggests that surgical stress in laparoscopic surgery may be attributable mainly to the effects of pneumoperitoneum.
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