Clinical techniques to prevent cough at emergence from general anaesthesia: A meta-analysis

Abstract

Brief summary: Various techniques can reduce the incidence of cough at tracheal extubation. Whilst effect size differs between treatments, homogeneity was identified within each subgroup of treatments. This meta-analysis allows anaesthesiologists to make informed choices on the use of techniques to prevent emergence cough. Background: Cough at extubation increases the risk of morbidity following surgical procedures. So, prevention of cough may aid perioperative risk management. Several techniques have been described for prevention of cough at or immediately after tracheal extubation. This meta-analysis compares various pharmacological methods for prevention of cough at emergence from general anaesthesia and aims to establish an evidence base for the rational use of these techniques. Methods: Several electronic databases (1966-2018) were searched systematically for randomised controlled trials that reported the incidence of cough at extubation. The quality of the studies identified was assessed using the Jadad methodology. Six techniques to prevent cough were analysed using the Mantel-Haenszel fixed-effects model. The odds ratio (OR) and number needed to treat (NNT) were used as the summary efficacy measures. Results: Of 1114 articles screened, 22 comparisons in 17 studies (1007 patients) were included in the final analysis. Significant heterogeneity of effect was observed when all studies were analysed together. However, there was homogeneity within each treatment subgroup. This reflected significant effect-size differences between techniques. The largest effect-sizes were seen with endotracheal tube cuff inflation with alkalinised lignocaine (pooled OR 0.052; 95% CI 0.027-0.102; NNT 1.67) and topical lignocaine (pooled OR 0.065; 95% CI 0.015-0.274; NNT 2.35). Conclusion: The incidence of cough at extubation of the trachea can be reduced. The overall effect size of the studied strategies was useful (pooled OR 0.149; 95% CI 0.13-0.18; NNT 2.62). No single technique prevented cough in all patients but cuff inflation with alkalinised lignocaine and topical 4% lignocaine were most effective.