Endogenous morphine levels after laparoscopic versus open colectomy

Background: Endogenous morphine may be a component of the acute-phase response to surgical trauma that affects both hospital stay and gastrointestinal motility. The purpose of this study was to assess the responses of endogenous morphine, stress hormones and cytokines following laparoscopic and open colectomy. Methods: Twenty patients who underwent a laparoscopic colectomy were compared with ten who had an open procedure. Data collected included operative blood loss, operating time and time to pass flatus. Plasma endogenous morphine was measured before and immediately after operation, and 3, 24 and 48 h later. Results: Age was comparable in the two groups. Operating time (mean 92.2 versus 61.3 min), time to tolerance of solid food (56.8 versus 103.6 h) and hospital stay (median 4 versus 6 days) were all significantly longer in the open group. Endogenous morphine levels rose immediately after open colectomy only and were higher than those after laparoscopic colectomy (8.69 versus 1.97 ng/ml; P < 0.001). Levels remained significantly higher in the laparoscopic group at 3 h (10.36 versus 0.52 ng/ml; P < 0.001) and 24 h, but were similar in both groups after 48 h. Conclusion: There is a greater degree of morphine synthesis after open than laparoscopic colectomy.