Singh 2010.

Methods	RCT, parallel design
Participants	Total number of randomized participants: 75 Inclusion criteria: ASA status I and II; 18‐45 years of age; undergoing elective surgery under GA requiring intubation Exclusion criteria: cardiovascular, plumonary, hepatic, and renal disease; people on beta‐blockers; difficult airways; laryngoscopy and intubation time > 30 seconds, or requiring > 2 attempts Type of surgery: elective surgery (type not specified, we assumed non‐cardiac) Baseline characteristics Intervention group (esmolol) Age, mean: 31.08 years Gender, M/F: 15/10 Intervention group (labetalol) Age, mean: 30.56 years Gender, M/F: 15/10 Control group (placebo) Age, mean: 30.28 years Gender, M/F: 17/8 Country: India Setting: single centre; hospital
Interventions	Intervention group (esmolol) Randomized, n = 25; losses = 0; analysed, n = 25 (use of ITT analysis not reported) Details: 0.5 mg/kg esmolol diluted to 10 mL with normal saline, given 2 min prior to intubation, and normal saline given 5 min prior to intubation. Study period was 10 min Intervention group (labetalol) Randomized, n = 25; losses = 0; analysed, n = 25 (use of ITT analysis not reported) Details: 10 mL normal saline administered 2 min prior to intubation and 0.25 mg/kg labetalol diluted to 10 mL with normal saline given 5 min prior to intubation Control group (placebo) Randomized, n = 25; losses = 0; analysed, n = 25 Details: 10 mL normal saline IV, given 2 min and 5 min prior to intubation
Outcomes	Outcomes measured/reported by study authors: haemodynamic variables; atrial ectopics; bradycardia (HR < 50 bpm) Outcomes relevant to the review: bradycardia (see notes below)
Notes	Funding/declarations of interest: no sources of funding. Study authors report no conflicts Study dates: March 2006‐August 2007 Note: we combined both beta‐blocker groups in analysis we did not include data for bradycardia in analysis because we could not be certain whether data were measured in all groups; study authors reported that 7 participants in the labetolol group experienced bradycardia
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization
Allocation concealment (selection bias)	Low risk	Use of sequentially numbered, opaque, sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind placebo‐controlled trial. We assumed that anaesthetists were blinded to group allocation
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	Unclear risk	Timings of administration of esmolol and labetolol differed between groups. We did not know whether this may influence results