title: Preemptive analgesia effects of ketamine in patients undergoing surgery. A meta-analysis.
abstract: OBJECTIVE
  To evaluate the preemptive analgesia effects of ketamine for postoperative pain.
  
  
  METHODS
  PubMed, EMBASE and Cochrane Library were searched to identify randomized controlled trials (RCTs) involved in ketamine for preemptive analgesic up to March 2013. The relative risk (RR) or mean difference (MD) as well as the confounding 95% confidence interval (CI) were calculated by the Revman 5.0 software.
  
  
  RESULTS
  A total of five studies including 266 patients were included in this meta-analysis. Overall, ketamine could reduce the postoperative morphine consumption and significantly prolong the time to first analgesic (p < 0.00001, MD = 0.91, 95% CI: 0.56 to 1.26). However, there was no significant difference in indicators of nausea and vomiting (p = 0.87, RR = 1.04, 95% CI: 0.67 to 1.60), surgical time (p = 0.41, MD = -2.13, 95% CI: -7.21 to 2.95) and anesthetic time (p = 0.53, MD = -1.54, 95% CI: -6.34 to -3.26) between ketamine and control group.
  
  
  CONCLUSIONS
  Ketamine was able to accomplish some preemptive analgesic effects of reducing postoperative morphine consumption and prolonging the time to first analgesic. Meanwhile, ketamine was as safe as physiological saline in side effects of nausea and vomiting.
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Liqiao
authors.initials: L
authors.lastname: Yang
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Chengmi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhao
authors.affiliation: School of Medicine, Jiao Tong University, Shanghai, China.
authors.forename: Jingjie
authors.initials: J
authors.lastname: Li
mesh_terms: D000700:Analgesics / Q000009:adverse effects / Q000627:therapeutic use*; D000701:Analgesics, Opioid / Q000008:administration & dosage; D006801:Humans; D007649:Ketamine / Q000009:adverse effects / Q000627:therapeutic use*; D009020:Morphine / Q000008:administration & dosage; D061646:Operative Time; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D020250:Postoperative Nausea and Vomiting / Q000209:etiology; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D007649:Ketamine; D009020:Morphine