Effectiveness of ketamine gargle in reducing postoperative sore throat in patients undergoing airway instrumentation: a systematic review.

BACKGROUND: Postoperative sore throat is a common, minor adverse event, second to postoperative nausea and vomiting, occurring in individuals undergoing general anesthesia. Postoperative sore throat has the potential to not only diminish patient satisfaction, but also increase the need for adjunct pain therapy in the post anesthesia care unit. Many techniques are utilized to reduce postoperative sore throat; however no one intervention has proven to be completely effective. The use of ketamine gargle is a novel intervention but the effectiveness of administering it prior to induction of general anesthesia is still uncertain. Therefore, further evaluation of current evidence is needed to determine the effectiveness of ketamine gargle in reducing the incidence of postoperative sore throat.

OBJECTIVES: The objective of this review was to determine the effectiveness of ketamine gargle in comparison to placebo or another intervention in reducing the incidence of postoperative sore throat in patients undergoing airway instrumentation.

INCLUSION CRITERIA: The participants in this review were adult patients who received ketamine gargle or placebo prior to induction of general anesthesia for a variety of surgical procedures requiring endotracheal intubation.This review examined studies that evaluated the effectiveness of ketamine gargle compared to placebo or another intervention in reducing the incidence of postoperative sore throat.This review considered studies that measured the incidence of postoperative sore throat using a direct question survey with a four-point scale (0 = no sore throat; 1,2,3 = presence of sore throat).This review included randomized controlled trials only; no other types of articles were discovered upon searching.

SEARCH STRATEGY: The comprehensive search strategy aimed to find both English language studies prior to August 2014.Databases used were: EMBASE, CINAHL, MEDLINE, ProQuest, Web of Science and Cochrane Central Register of Controlled Trials. Google Scholar, MEDNAR, New York Academy of Medicine Grey Literature Report and ProQuest Dissertations and Theses were used to locate unpublished studies. Initial keywords included: ketamine, gargle or mouthwash, postoperative, sore throat or pharyngitis, and airway management.

METHODOLOGICAL QUALITY: Two independent reviewers used the Joanna Briggs Institute Critical Appraisal Checklist for Experimental Studies, a standardized critical appraisal instrument, to assess papers selected for inclusion.

DATA EXTRACTION: Incidence of postoperative sore throat for both the treatment and control groups was extracted from the included studies using the Joanna Briggs Institute Data Extraction Form for Experimental Studies.

DATA SYNTHESIS: Extracted data was pooled in a meta-analysis utilizing the DerSimonian and Laird random effects model using the JBI Meta-Analysis of Statistics Assessment and Review Instrument. Relative risk and 95% confidence intervals were calculated for analysis. Heterogeneity was assessed using the standard chi-square test.

RESULTS: Five randomized controlled-trials were included in the meta-analysis. Ketamine gargle caused a statistically significant (p <0.015, RR <0.53) reduction in the incidence of postoperative sore throat compared to placebo across all five time intervals studied (0, 2, 4, 8, and 24 hours).

CONCLUSIONS: Administration of ketamine gargle (40-50 mg) prior to induction of anesthesia significantly reduces the incidence of postoperative sore throat across all studied time intervals in patients undergoing general anesthesia requiring endotracheal intubation.

IMPLICATIONS FOR PRACTICE: Administration of ketamine gargle prior to induction of general anesthesia with airway instrumentation may improve patient satisfaction by decreasing patient discomfort and the need for adjunct pain therapy in the post anesthesia care unit. This impacts current practice and patient outcomes in that this may decrease the need for adjunct pain therapy and decrease length of stay in the post-anesthesia care unit.

IMPLICATIONS FOR RESEARCH: Additional research is needed to determine the systemic effects of ketamine gargle and whether other n-methyl-d-aspartate antagonists are effective in reducing postoperative sore throat. Future research should include previously excluded populations and expanded to include other methods of airway manipulation.