Perioperative intravenous ketamine for acute postoperative pain management in adult cancer patients undergoing solid tumor resection: a systematic review and metaanalysis
Author(s): Bolívar-Trujillo M., Escobar B. 
Institute(s): Universidad Nacional de Colombia, Dept of Anaesthesiology, Bogota, Colombia
Background and Goal of Study: Surgery is the principal treatment for adult oncology patients. Suboptimal acute pain management increases morbidity and chronic pain. Several analgesic drugs could have an effect on tumor progression. There is evidence that opioid drugs have the potential of decreasing innate and adaptive inmune response for neoplastic processes. The main objective is to evaluate the efficacy of perioperative intravenous ketamine for acute postoperative pain management and opioid sparing effect on adult oncology patients undergoing solid tumor resection.
Materials and Methods: Systematic review and metaanalysis of randomized controlled clinical trials searched in these databases: CENTRAL, Medline, EMBASE, LILACS, and exploring gray literature, following the Cochrane recommendations. The outcomes were the analgesic efficacy measured by analog visual scale from 0-100 during the first postoperative 24 hours and the cumulative opioid requirements in the same period. The security outcome was intended to report adverse effects of the intervention, and the implication for chronic postoperative pain and tumoral recurrence. The security outcome was intended to report adverse effects of the intervention, and the implication for chronic postoperative pain and tumoral recurrence. The search was conducted independently by two investigators. The information was extracted using an standard template, which also evaluates the risk of bias.
Results and Discussion: We included 5 randomized clinical trials over 101 studies found. The metaanalysis of analgesic efficacy showed reduced pain intensity at rest during the 6 (MD -12.58 [-22.42, -2.73]) and 12 postoperative hours (MD - 10.55 [-19.76, -1.34]) but not at 24 (MD -7.34 [-16.19, 1.52]). The opioid sparing effect was not significant at 24 hours (MD -4.67mg [-12.62, 3.28]). However, the calculated heterogeneity with I2 was greater than 80%, even using a sensitivity analysis. There was not a clinical difference for adverse events and postoperative nausea and vomiting. One of the trials concluded a decreased postoperative chronic pain at 6 months. There was no report of oncologic recurrence.
Conclusion: Perioperative intravenous ketamine in adult oncologic patients undergoing solid tumor resection has an analgesic efficacy during the first 12 postoperative hours, without opioid sparing effect, despite significant heterogeneity between the studies. There is lack of evidence around the tumor progression.

Perioperative intravenous ketamine for acute postoperative pain management in adult cancer patients undergoing solid tumor resection: a systematic review and metaanalysis