Conditions: Post Operative Pain Hyperalgesia
Keywords: hyperalgesia Patient controlled analgesia morphine methadone ketamine
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 113
Healthy volunteers: no

Brief summary:
Background: In perioperative period inhibition of N-Methyl-D-Aspartate receptor prevents opioid-induced hyperalgesia and reduce postoperative opioid requirement after abdominal surgery. Methadone is both a µ-opioid receptor agonist like Morphine and a N-Methyl-D-Aspartate antagonist. Study Aim. To evaluate the efficacy of intraoperative Ketamine and postoperative Methadone analgesia in preventing opioid-induced hyperalgesia after abdominal surgery.

Detailed description:
not desired

Arms:
arm 1: Patient received a standard balance anaesthesia and morphine for post operative pain. arm 2: Ketamine infusion scheme: 5mcg/Kg/min from induction od anaesthesia for 10 min, than 2,5mcg/Kg/min for 20 min and than 2 mcg/Kg/min to the end of surgery. arm 3: Methadone PCA arm 4: Ketamine infusion scheme: 5mcg/Kg/min from induction od anaesthesia for 10 min, than 2,5mcg/Kg/min for 20 min and than 2 mcg/Kg/min to the end of surgery.

Methadone administered by a PCA system (dose 2 mg, lock-out 12min.).

Interventions: intervention 1: ketamine infusion intervention 2: Methadone PCA
Intervention descriptions: intervention 1: Ketamine infusion scheme: 5mcg/Kg/min from induction od anaesthesia for 10 min, than 2,5mcg/Kg/min for 20 min and than 2 mcg/Kg/min to the end of surgery intervention 2: Methadone administered by a PCA system (dose 2 mg, lock-out 12min.)

Protocol document: