Background: Emergence coughing can harm the patient following completion of surgery, but it is unclear which medication is most effective at reducing this event. We conducted a systematic review and network meta-analysis of RCTs to determine the medications' relative efficacies on decreasing moderate to severe emergence coughing after general anaesthesia. Medications studied were lidocaine (i.v., intracuff, topical, or tracheal application), dexmedetomidine, remifentanil, and fentanyl. Methods: We searched eight different medical literature databases, conference abstracts, and article references. After screening, included citations were evaluated for bias and had their data extracted. Pooled odds ratios and 95% confidence intervals for each treatment comparison were calculated. A surface under the cumulative ranking curve analysis (SUCRA) determined the relative rank of each intervention to decrease moderate to severe emergence coughing. Subgroup analyses included severe coughing only, extubation times, type of maintenance anaesthetic, and dosages. Results: The network meta-analysis included 70 studies and 5286 patients. All study medications had favourable odds in reducing moderate and severe peri-extubation coughing compared with either no medication or placebo. No single medication was favoured over another. Dexmedetomidine had the highest SUCRA rank, followed in order by remifentanil, fentanyl, and lidocaine via intracuff, tracheal/topical, and i.v. routes. Remifentanil was ranked highest for decreasing severe coughing only. Intracuff lidocaine had higher odds of prolonging extubation times compared with placebo, dexmedetomidine, fentanyl, and remifentanil. Conclusion: All study medications were better than placebo or no medication in reducing moderate to severe emergence cough, with dexmedetomidine ranked the most effective. Systematic review registration: PROSPERO registration number: CRD42018102870. Editor's key pointsThe authors examined the literature to establish the effectiveness of various drugs in reducing coughing around the time of tracheal extubation.Dexmedetomidine, remifentanil, fentanyl, and lidocaine all reduced the incidence of moderate to severe emergence coughing. Dexmedetomidine appeared to be the most effective medication for decreasing the frequency of moderate to severe emergence cough.

BackgroundEmergence coughing and bucking, secondary to endotracheal tube stimulation of the tracheal mucosa, frequently occurs after the general anesthetic recedes. Besides general unpleasantness, coughing has important physiological sequelae that may be detrimental to the postoperative patient. Multiple pharmacological strategies have been published, but prior systematic reviews on this topic have neither been comprehensive enough in their literature or medication search, nor provided us the answer regarding what the best pharmacological method is to prevent or minimize peri-extubation coughing. Our systematic review and network meta-analysis’ primary objective is to determine the relative efficacies of different pharmacological methods on decreasing coughing (none to mild compared to moderate to severe, as defined by the modified Minogue scale) during emergence after a general anesthetic with endotracheal intubation in adult elective surgeries. Medications of interest are lidocaine or lignocaine (intravenous (IV), intracuff alkalinized, intracuff non-alkalinized, topical, endotracheal application), dexmedetomidine IV, remifentanil IV, and fentanyl IV. These medications were selected based on a preliminary review of the literature.MethodsUsing a predefined search strategy, we will search MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Cochrane Database of Systematic Reviews, ACP Journal Club, Database of Abstracts of Reviews of Effects, and the Cochrane Methodology Register, with no date or language restrictions. Gray literature search will encompass conference abstracts, Web of Science, and references from publications selected for full-text review. Two reviewers will independently screen the retrieved literature using predetermined inclusion criteria, process publications selected for full-text review, extract data from publications chosen for study inclusion, and evaluate for bias using the Cochrane risk of bias assessment. Risk ratios and 95% confidence intervals will be calculated for each study, and a surface under the cumulative ranking curve will determine the relative rank of each intervention in its ability to prevent coughing on emergence.DiscussionThe proposed systematic review and network meta-analysis will not only provide a more thorough review of common medications used to decrease emergence coughing, but also inform clinicians which of these pharmacological strategies is the best approach.Systematic review registrationPROSPERO CRD42018102870

The young pulsar PSR B1828−11 has long been known to show correlated shape and spin-down changes with timescales of roughly 500 and 250 days, perhaps associated with large-scale magnetospheric switching. Here we present multi-hour observations with the Parkes and Green Bank Telescopes at multiple phases across the ∼500-day cycle and show that the pulsar undergoes mode-changing between two stable, extreme profile states. The fraction of time spent in each profile state naturally accounts for the observed overall "shape parameter" (defined to be 0 for wide profiles and 1 for narrow ones); this and the variable rate of the mode transitions are directly related to the spin-down changes. We observe that the mode transition rate could plausibly function as an additional parameter governing the chaotic behaviour in this object

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