Kao 2017.

Methods	RCT, parallel design
Participants	Total number of randomized participants: 20 Inclusion criteria: ASA status I female participants; 20‐50 years of age; undergoing minor breast surgery. Participants were free of known systemic diseases, not receiving medication, had no improper drug or alcohol misuse, and BMI between 18.5 and 24.9 kg/m² Exclusion criteria: not reported Type of surgery: minor breast surgery Baseline characteristics Intervention group (esmolol) Age, mean (SD): 39.9 (± 9.4) years Control group (saline) Age, mean (SD): 40.4 (± 8.1) years Country: Taiwan Setting: single centre; hospital
Interventions	Intervention group (esmolol) Randomized, n = 10; losses = 2 (due to unsatifactory placement of LMA); analysed, n = 8 (ITT analysis was not used) Details: during anaesthesia, esmolol 0.5 mg/kg IV bolus Control group Randomized, n = 10; losses = 2 (due to unsatifactory placement of LMA, and unsatisfactory ECG recording); analysed, n = 8 (ITT analysis was not used) Details: normal saline 0.05 mL/kg, not described as a placebo
Outcomes	Outcomes measured/reported by study authors: hypotension (drop from 30% or baseline SBP); bradycardia (HR < 50 bpm); HR variability Outcomes relevant to the review: hypotension; bradycardia
Notes	Funding/declarations of interest: grants from Chang Gung Memorial Hospital, Taiwan, and the Ministry of Science and Technology, Taiwan. Study authors declare no conflicts Study dates: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Use of a sealed envelope technique. Insufficient information
Allocation concealment (selection bias)	Unclear risk	Not specified
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	It is not clear whether the control group was a placebo agent, and whether the anaesthetists were aware of group allocation
Blinding of outcome assessors (detection bias) All outcomes	Unclear risk	Not specified
Incomplete outcome data (attrition bias) All outcomes	High risk	Small sample size with 2 participant losses in each group (20% loss)
Selective reporting (reporting bias)	Unclear risk	Study authors did not report prospective clinical trial registration or publication of a protocol. It was not feasible to effectively assess risk of reporting bias
Other bias	Low risk	Not detected