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

Endogenous morphine in the brain leads to various biological responses after surgery. The aim of this study was to determine whether morphine levels in the plasma would be enhanced by open laparotomy rather than by laparoscopic procedures.We compared 19 patients who underwent laparoscopic cholecystectomy with five patients who underwent resection of the gallbladder by open laparotomy. Morphine levels in the plasma were measured by an electrochemical detection system.Postoperative endogenous morphine levels were higher with open laparotomy than with the laparoscopic technique (three h after surgery: open, 200 +/- 52.6 fmol/ml vs laparoscopy, 17.6 +/- 3.7, p0.01). This morphine elevation accounted for higher levels of cytokine, greater pain scores, and longer duration of fasting in open laparotomized patients than in laparoscopic cholecystectomy patients. Stress hormone levels in the plasma were also higher with open laparotomy than with laparoscopy.Morphine synthesis was enhanced by open laparotomy, resulting in greater biological response postoperatively than that seen with laparoscopic cholecystectomy.