Date	Event	Description
1 September 2019	New search has been performed	We conducted a search for new studies We included 10 new studies. The remaining studies were previously included in Blessberger 2018.
1 September 2019	New citation required but conclusions have not changed	The previous version of the review assessed evidence in cardiac and non‐cardiac surgery (Blessberger 2018). We split the review according to type of surgery. The current version assesses the evidence only in cardiac surgery. The evidence for non‐cardiac surgery is reported in (Blessberger 2019). We added three new review authors (Sharon Lewis, Michael Pritchard, Lizzy Fawcett). Three review authors (Danyel Azar, Martin Schillinger, Franz Wiesbauer) were not included in this update. We reduced the number of outcomes to improve the manageability and focus of the review. Myocardial ischaemia, supraventricular arrhythmias (except for atrial fibrillation), ventricular extrasystoles, bronchospasm, and cost of care are not included; effect estimates for these can be found in the previous version (Blessberger 2018). We did not conduct meta‐regression or trial sequential analysis. We explored heterogeneity through subgroup analysis and decisions made as part of the review process through sensitivity analysis. We included 10 new studies. Conclusions remain unchanged.
22 February 2018	New citation required but conclusions have not changed	Removal of retracted study in non‐cardiac surgery (Suttner 2009); conclusions unchanged.
22 February 2018	Amended	Following publication of the first version of this systematic review, a previously included study was retracted (Suttner 2009). This trial has now been excluded and all relevant analyses and results have been amended accordingly. All NNTB/Hs were recalculated according to the formula in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Guideline recommendations were updated in the Discussion section.