The aim of this study was to evaluate the effect of intraoperative methadone on postoperative analgesic requirements, pain scores and patient satisfaction in comparison to standard intraoperative pain control with fentanyl.

Patients of both genders and up to age 75 and ASA classification III were enrolled, when undergoing moderately to severely painful surgery scheduled for ≥90 minutes in general anaesthesia. Patients were randomized to receive either a single shot of methadone (0.2mg/kg) or fentanyl (0.003mg/kg) for induction of anesthesia. In cases of insufficient intraoperative analgesia repeated fentanyl administration was possible. Postoperative analgesia was provided with patient controlled morphine in both groups (PCA = Patient Controlled Analgesia). Pain was assessed using the numerical rating scale (NRS) at rest and after coughing, at 15 minutes post extubation, and repeated every 6 hours up to 72 hours postoperatively. The levels of sedation and nausea/vomiting were also evaluated in parallel.

Inclusion Criteria:

• informed consent
• Patients of both genders and up to age 75 and ASA classification III were enrolled, when undergoing moderately to severely painful surgery scheduled for ≥90 minutes in general anaesthesia.
• german speaking patients

Exclusion Criteria:

• patients including other studies
• pregnant
• breast feeding
• patients in methadone substitution therapy
• dependent drug user
• patients with BMI greater than 36kg/m2
• patients with chronic or acute renal failure with serum creatinine greater than 400µmol/L
• patients with liver insufficiency or failure
• alcoholics
• patients with acute heard attack