title: Efﬁcacy of the prophylactic administration of tramadol against postoperative shivering: a meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Postoperative shivering (POS) is a common complication that occurs after regional and general anesthesia. Thus far, numerous studies have reported on the effectiveness of tramadol in preventing or treating POS. Here, we performed a meta-analysis to assess the efficacy of tramadol in the prevention of POS.
  
  
  METHODS
  We systematically searched PubMed, Embase and the Cochrane Library to identify studies of the efficacy of tramadol in the prevention of POS. The results are expressed as relative ratios (RRs) and the corresponding 95% confidence intervals (CIs).
  
  
  RESULTS
  Seventeen studies with a total of 1438 patients were included. Seven hundred seventy-seven of these patients received tramadol, and 661 received placebo. Compared with placebo, the patients who received tramadol exhibited a significant reduction in the incidence of POS based on subgroup analyses according to anesthesia (RR: 0.27; 95% CI: 0.19-0.37; P<0.00001), different doses of tramadol (RR: 0.26; 95% CI: 0.19-0.35; P<0.00001), the rescue drug used (RR: 0.19; 95% CI: 0.10-0.35; P<0.00001) and the number of patients who experienced severe POS (RR: 0.17; 95% CI: 0.12-0.23; P<0.00001). Moreover, the administration of tramadol did not increase the risks of postoperative nausea and vomiting (PONV), hemodynamic turbulence, respiratory depression or deep sedation.
  
  
  CONCLUSIONS
  This meta-analysis revealed that prophylactic tramadol effectively prevents POS and reduces rescue medication use without significant adverse effects.
authors.affiliation: Department of Anesthesiology, West China Second Hospital of Sichuan University, Key Laboratory of Birth Deficits and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, West China Second Hospital of Sichuan University, Key Laboratory of Birth Deficits and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, West China Second Hospital of Sichuan University, Key Laboratory of Birth Deficits and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China - xuemeilinscu@163.com.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Lin
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D006801:Humans; D011183:Postoperative Complications / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D012768:Shivering / Q000187:drug effects*; D014147:Tramadol / Q000627:therapeutic use*
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol