The Effect of Intraoperative Ketamine on Opioid Consumption and Pain After Spine Surgery in Opioid-dependent Patients

Ketamine (25 mg/ml) bolus 0.5 mg/kg administered immediately after induction of anesthesia, followed by infusion ketamine 0,25 mg/kg/hour that is terminated when the last suture to the skin has been performed.

Isotonic sodium chloride 0.9 percent 0.02 ml/kg administered immediately after induction of anesthesia, followed by infusion isotonic sodium chloride 0.01 ml/kg/hour that is terminated when the last suture to the skin has been performed.

Paracetamol 1 g orally 1 hour preoperatively and every 6 hours after extubation time during the first 24 hours.

Morphine Sulphate 1 mg/ml administered as patient-controlled analgesia (PCA, bolus 2.5 mg, lockout 5 minutes) 0-24 hours postoperatively

Morphine Sulphate 1 mg/ml, bolus 2.5 mg administered by the PACU nurse on request of the patient for the first hour postoperatively.

Ondansetron 2 mg/ml 4 mg iv in case of moderate to severe nausea, supplemented by Ondansetron 1 mg iv if needed

The patients usual daily opioid consumption are administered during the study period

Morphine Sulphate 1 mg/ml, bolus 0.4 mg/kg administered 45 minutes before expected awakening.

Sufentanil 5 microgram/ml, bolus 5 micrograms administered by the anaesthetic nurse in the operating room if the patient is in pain upon awakening.