Author Year Surgical setting Dosing Timing Outcomes
Single studies
Jha et al. [36 ] 2013 Cleft palette repair 0.5 mg/kg infiltration of surgical site Lower pain score than bupivacaine (2 mg/kg) at 24 h, less rescue analgesia required Eghbal et al. [37 ] 2013 Adenotonsillectomy 0.25 mg/kg IV bolus Decreased emergence agitation, acetaminophen requirements, and pain scores Nitta et al. [39 ] 2013 Cervical and lumbar spinal surgery 2.0 mg/kg/h IV Bolus given for 5 h periop. (total of 10 mg/kg total) Reduction in PCA requests and total morphine distributed at 24, 36, 48, and 60 hours Hadi et al. [40 ] 2013 Lumbar microdiscectomy 1 Peri- and postop. for a total of 24 h Decreased total morphine consumption, pain scores, and PONV Kim et al. [41 ] 2013 Lumbar spinal fusion 0.5 mg/kg bolus, 2 Infusion for 48 h postop. Less fentanyl requirement postop. Cengiz et al. [43 ] 2014 Total knee replacement 6 Periop. only Reduction in morphine consumption at 1, 3, 6, 12, and 24 h, lower pain scores Nesher et al. [46 ] 2008 Thoracic surgery 1 mg morphine and 5 mg ketamine IV-PCA Morphine consumption and patients requiring PCA at 36 h reduced by 50%; decreased pain scores and PONV Suppa et al. [48 ] 2012 Cesarean section 0.5 mg/kg bolus, 2 Bolus @ 10 min postop. then infusion for 12 h Reduced pain sensitivity at T-10 dermatome Zakine et al. [49 ] 2008 Major abdominal surgery 0.5 mg/kg bolus, 2 Periop. bolus, infusion for 48 h Decreased morphine consumption, pain scores, and PONV
de Kock et al. [50 ] 2001 Rectal adenocarcinoma resection 0.5 mg/kg bolus, 0.25 mg/kg/h IV infusion Periop. infusion only Lower morphine requirements, smaller hyperalgesic areas, and less pain at 6 months of follow-up
Systematic reviews and meta-analyses Cho et al. [38 ] 2014 Tonsillectomy Various Preop. dosing Decreased pain at 4 h, decreased analgesic need at 24 h Laskowski et al. [51 ] 2011 Various Various Various 100% of ketamine groups required less postop. opioids, 78% reported less postop. pain
Elia and Tramèr [52 ] 2005 Various Various Various Decrease in morphine consumption, longer time to first analgesic request, less pain at 6 months of follow-up Subramaniam et al. [34 ] 2004 Various Various Various Single bolus-less opioid consumption in 64% of trials; continuous infusion-less opioid consumption in 55% of trials; epidural infusion-beneficial in 63% of trials McCartney et al. [53 ] 2004 Various 0.15–1.0 mg/kg, various routes Various Decreased postop. pain and/or decreased analgesic consumption in 58% of trials’
