[Effectiveness of intravenous magnesium on postoperative pain after abdominal surgery versus placebo: double blind randomized controlled trial].

PURPOSE

the purpose of our trial is to evaluate the impact of the intravenous perfusion of magnesium on the morphin consumption and on the controle of the stress neuro-endocrin and metabolic reaction in major digestive surgery.

METHODS

prospective, randomized, double blinded study versus placebo.Including 42 ASA I patients, scheduled for major digestive surgery, randomized into two groups : Magnesium, receiving a bolus of magnesium sulfate; 50 mg/kg, followed by a continuous perfusion; 10 mg/kg/h for the 24 postoperative hours. The control group received the same volume of an isotonic saline solution.Postoperative analgesia was assured by morphin PCA. The patients were evaluated by the pain visual analogic scale (VAs), the total dose of morphine consumed and the evolution of the biological markers of stress (glycemia, cortisol, ATH, prolactine and IL6) during the first 24 postoperative hours. Hemodynamic and respiratory parameters, side effects and patient satisfaction were recorded.

RESULTS

the total dose of morphine consumed during the first 24 postoperative hours,was equivalent in the two groups (44,49+/-6,4 vs 45,26+/-9,1 mg; p= 0,59).the initial pain VAS means were equivalent (68 mm +/- 15 vs 71 mm+/-14). Ulterior pain VAS means, after morphin titration then with PCA were also equivalent and less to 40 mm. the global amplitude and the evolution of the stress markers evaluated by the surface under curbs were comparable in the two groups, despite a magnesemia twice higher than the normal values in the magnesium group.the satisfaction and the incidence of side effects were similar.

CONCLUSION

association of magnesium to morphin PCA does not help to reduce morphin consumption, and does not affect the control of the stress reaction in major digestive surgery.