Van den Berg 1998.

Methods	RCT, parallel design
Participants	Total number of randomized participants: 80 Inclusion criteria: ASA I‐III; middle‐aged to elderly healthy people; receiving treatment for diabetes, hypertension, ischaemic heart disease, or a combination of these diseases; scheduled for cataract extraction under GA because they were considered unsuitable for peribulbar analgesia due to senility, language barrier, chronic cough, renal failure, or an estimated inability to remain immobile in the supine position during surgery Exclusion criteria: asthma Type of surgery: cataract extraction under GA Baseline characteristics Intervention group (esmolol) Age, mean (SD): 67 (± 11) years Gender, M/F: 27/13 History of hypertension, n: 9 Preoperative use of beta‐blockers, n: 4 Control group (placebo) Age, mean (SD): 65 (± 11) years Gender, M/F: 21/19 History of hypertension, n: 4 Preoperative use of beta‐blockers, n: 2 Country: Saudi Arabia Setting: single centre; hospital
Interventions	Intervention group (esmolol) Randomized, n = 40; losses = 0; analysed, n = 40 (use of ITT analysis not reported) Details: 250 mg/mL esmolol IV given immediately after induction at rate of 4 mg/kg. Then 60 seconds before eye bandaging at rate of 2 mg/kg, then 60 seconds prior to extubation at rate of 2 mg/kg Control group (placebo) Randomized, n = 40; losses = 0; analysed, n = 40 Details: normal saline, given same as the intervention group
Outcomes	Outcomes measured/reported by study authors: haemodynamic parameters; bradycardia (HR < 50 bpm and treated with atropine) Outcomes relevant to the review: bradycardia (see notes below)
Notes	Funding/declarations of interest: not reported Study dates: January 1995‐April 1996 Note: we did not include data for bradycardia in analysis because data were unclearly reported in study tables and text
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Use of block randomization
Allocation concealment (selection bias)	Low risk	Use of sealed envelopes, and preparation of syringes by anaesthetists were blinded to treatment groups
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Anaesthetists were blinded, use of coded syringes
Blinding of outcome assessors (detection bias) All outcomes	Unclear risk	Not specified
Incomplete outcome data (attrition bias) All outcomes	Low risk	No apparent losses
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