Patients with a daily use of opioids may develop higher postoperative pain levels, often need high doses of morphine and therefore their pain may be difficult to treat. A low dose of an old anesthetic drug, ketamine, administered during surgery can possibly reduce pain and morphine consumption in these patients. Our purpose is to investigate the effect of low dose ketamine on morphine consumption and pain after spine surgery in patients with a daily use of opioids. Our hypothesis is that low dose ketamine can reduce morphine consumption, pain and side-effects after spine surgery.
Opioid-dependent patients can develop hyperalgesia and often have a high opioid consumption postoperatively due to opioid tolerance. Intraoperative ketamine in subanesthetic doses can possibly reduce hyperalgesia and reduce opioid-tolerance in these patients. Ketamine is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist that works by blocking the NMDA receptors in the central and peripheral nerve system. It can be used for general anesthesia but the drug also has other properties including lowering of central excitability and reducing postoperative opioid tolerance by modeling the opioid receptors. Further more it can possibly reduce chronic pain by blocking wind-up effect when blocking the NMDA receptors. Our purpose is to investigate the effect of intraoperative ketamine on opioid consumption and pain after spine surgery in opioid-dependent patients. Our hypothesis is that ketamine can reduce opioid consumption and reduce postoperative pain and side effects compared to placebo.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
147
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.
Department of Anaesthesiology, Glostrup Hospital
Glostrup Municipality, Denmark
Morphine consumption
Total intravenous morphine consumption, other than the patients usual opioid use, 0- 24 hours postoperatively, administered as patient-controlled analgesia ((PCA), bolus 2.5 mg, lockout 5 minutes)
Time frame: 0-24 hours postoperatively
Pain during mobilization
Pain score during active mobilization, measured on a visual analogue scale (VAS) (0-100 mm), defined as a standardized movement from recumbent position to sitting on the bedside at 2, 6, 12, 18 and 24 hours postoperatively, the worst pain from the movement is registered. The endpoint, VAS-mobilization, will be calculated as area under the curve (AUC) (2-24h) from these measurements.
Time frame: 2, 6, 12, 18 and 24 hours postoperatively
Pain at rest
Pain score at rest, measured on a visual analogue scale (VAS) (0-100 mm), at 2, 6, 12, 18 and 24 hours postoperatively. The endpoint, VAS-rest, will be calculated as area under the curve (AUC) (2-24h) from these measurements.
Time frame: 2, 6, 12, 18 & 24 hours postoperatively
Nausea
Level of nausea (none, mild, moderate, severe) (0-24h), measured at 2, 6, 12, 18 and 24 hours postoperatively.
Time frame: 2, 6, 12, 18 & 24 hours postoperatively
Vomiting
Number of vomiting episodes (0-24 hours), registered in the periods 0-2, 2-6, 6-12, 12-18, 18-24 hours postoperatively.
Time frame: 0-2, 2-6, 6-12, 12-18, 18-24 hours postoperatively
Ondansetron
Consumption of ondansetron (mg) during 0-24 hours postoperatively.
Time frame: 0-24 hours postoperatively
Sedation
Level of sedation (none, mild, moderate, severe) (0-24 h) registered at time 2, 6, 12, 18 and 24 hours postoperatively.
Time frame: 2, 6, 12, 18 & 24 hours postoperatively
Hallucinations and nightmares
Episodes of hallucinations and nightmares (yes/no) in the period 0-24 hours postoperatively.
Time frame: 0-24 hours postoperatively
Chronic pain
Level of chronic pain and daily use of opioids assessed by the validated questionnaires EQ50, OWESTRY and DN4 at 6 months postoperatively.
Time frame: 6 months postoperatively
Chronic pain
Level of chronic pain and daily use of opioids assessed by the validated questionnaires EQ50, OWESTRY and DN4 at 12 months postoperatively.
Time frame: 12 months postoperatively
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