Effect of surgical stress on endogenous morphine and cytokine levels in the plasma after laparoscopoic or open cholecystectomy

Background Endogenous morphine in the brain leads to various biological res ponses after surgery. The aim of this study was to determine whether morphi ne levels in the plasma would be enhanced by open laparotomy rather than by laparoscopic procedures. Methods: We compared 19 patients who underwent laparoscopic cholecystectomy with five patients who underwent resection of the gallbladder by open lapa rotomy. Morphine levels in the plasma were measured by an electrochemical d etection system. Results: Postoperative endogenous morphine levels were higher with open lap arotomy than with the laparoscopic technique (three h after surgery: open, 200 +/- 52.6 fmol/ml vs laparoscopy, 17.6 +/- 3.7, p < 0.01). This morphine elevation accounted for higher levels of cytokine, greater pain scores, an d longer duration of fasting in open laparotomized patients than in laparos copic cholecystectomy patients. Stress hormone levels in the plasma were al so higher with open laparotomy than with laparoscopy. Conclusion: Morphine synthesis was enhanced by open laparotomy, resulting i n greater biological response postoperatively than that seen with laparosco pic cholecystectomy.