Randomized Controlled Trial
Pre-emptive analgesic efficacy of tramadol compared with morphine after major abdominal surgery.
Br J Anaesth. 2003 Aug 1; 91 (2): 209-13.
Randomized Controlled Trial
Postoperative extradural analgesia with morphine and ropivacaine. A double-blind comparison between placebo and ropivacaine 10 mg/h or 16 mg/h.
Acta Anaesthesiol Scand. 2005 Sep 1;49(8):1191-9.
Randomized Controlled Trial
Single-dose, sustained-release epidural morphine in the management of postoperative pain after elective cesarean delivery: results of a multicenter randomized controlled study.
Anesth. Analg. 2005 Apr 1;100(4):1150-8.