Efficacy and Safety of Prophylactic Use of Ketamine for Prevention of Postanesthetic Shivering

A Systematic Review and Meta Analysis

Yang Zhou; Abdul Mannan; Yuan Han; He Liu; Hui-Lian Guan; Xing Gao; Ming-Sheng Dai; Jun-Li Cao


BMC Anesthesiol. 2019;19(245) 

In This Article


This meta-analysis was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

Search Strategy

Two authors (Y.Z., A.M.) independently searched MEDLINE (2000 to March 2018), EMBASE (2000–2018), and the Cochrane Central Register of Controlled Trails (March 2018) with no language restrictions. By reviewing the references of the eligible articles, we identified additional studies relevant to our meta-analysis. The following search-term strategy was used:

1) shivering; 2) tremor; 3) shake; 4) hypothermia; 5) anesthesia; 6) postanesthetic; 7) postoperative; 8) surgery; 9) ketamine; 10) 1 or 2 or 3 or 4; 11) 5 or 6 or 7 or 8; 12) 9 and 10 and 11.

Criteria for Considering Studies for This Review

The selection criteria were pre-established. Inclusion criteria were: (1) controlled clinical trial; (2) prophylactic use of ketamine compared with a placebo or other pharmacological interventions; (3) reported the incidence of postoperative shivering. Trials were not considered for the following reasons: (1) other anti-shivering drugs were also administrated during the anesthetic induction or maintenance period besides ketamine; (2) data from abstracts, letters, or reviews. We included any participants undergoing operative procedures with general or spinal anesthesia. The following outcomes were measured: (1) incidence of postanesthetic shivering; (2) sedation score; (3) incidence of other side effects.

Data Collection and Analysis

Two review authors (Y.Z., A.M.) independently screened all the titles and abstracts of the studies during the initial search to identify the included studies. After removing the duplicates, potentially relevant studies were retrieved in full-text version for the further assessment. We resolved any disagreement by discussion with another author (G. H. L) of our group.

Data extraction was conducted by two authors (Y.Z., A.M.) independently using the data collection form established previously. The following data were collected from each study: primary author, publication year, anesthetic methods, demographic characteristics of participants, surgery types, comparisons, and other non-pharmacological warming methods. We recorded the number of patients experiencing shivering in each group for dichotomous data.

We used the Review Manager software of the Cochrane Collaboration (RevMan 5.2) to perform the quantitative analysis. The results of dichotomous data are expressed as odds ratio (OR) and 95% confidence intervals (CIs). Heterogeneity testing was performed with Z score and X2 statistical analysis; P < 0.1 was considered to indicate heterogeneity. The fixed effect model or the random effect model were applied according to the heterogeneity of the study. A fixed effect model was used when I2 < 50%. We reported the results of included studies when the pooled analysis was not appropriate. Sensitivity and subgroup analysis were performed to explore the reason for the heterogeneity. Subgroup analysis was conducted based on the anesthetic methods, various doses of ketamine used, and the types of surgery. Publication bias was evaluated by Begg's test using Stata 13.1 software (Stata, College Station, TX, USA).