Berry 1998.

Methods	Parallel‐group blinded randomized controlled trial, conducted in the United Kingdom. Study dates not reported
Participants	98 elective coronary artery bypass graft (CABG) patients, with no ECG abnormalities, not older than 71 years, with no digitalis therapy, no left or right bundle branch block, no morbid obesity (BMI > 35), with FEV1 or FVC > 50%, no poor left ventricular function. Patients were excluded from the study after surgery if they failed to meet the following criteria: haemodynamically stable; blood loss < 120 mL/h and arterial PO2 ≤ 7 kPa with an inspired oxygen concentration of 50%; and PEEP ≤ 5 cm H2O. Patients with < 10 hours of acceptable number of beats in the postbypass period and with abnormal QRS complexes (i.e. not artefact, ventricular ectopics or bundle branch block) were excluded from the ECG analysis.
Interventions	Low‐dose opioid, early extubation (within 8 hours) in 50 participants, but ECG analysis complete in 43 participants. Anaesthesia with fentanyl 15 μg/kg and isoflurane HIgh‐dose opioid, usual care (more than 8 hours) in 48 participants, but ECG analysis complete in 42 participants. Anaesthesia with fentanyl 50 μg/kg and isoflurane Details of weaning protocol and who decided when to extubate were not given.
Outcomes	Time to extubation Risk of mortality in the ICU Risk of postoperative myocardial ischaemia (defined non‐fatal myocardial infarction as concentrations of MB isoenzyme of creatine kinase (CK‐MB) levels > 130 IU/L and development of a new Q‐wave or new left bundle branch block on the postoperative 12‐lead ECG) Risk of major bleeding Hospital length of stay Length of stay in the ICU
Notes	Of 50 participants in the early extubation group, 3 failed early extubation in the designated period of 8 hours. Of 50 participants in the early extubation group, 2 had "excess blood loss (≥ 120 mL/h)". Power calculation was done. Details of any declarations of conflict of interest among study authors were not provided.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"On arrival in the operating room, patients were allocated to enter early extubation (group E) or late extubation (group L) according to a prepared randomization schedule"
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding (performance bias and detection bias) All outcomes	Low risk	Assessors were blinded to the diagnosis of myocardial ischaemic outcomes.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reasons and details for 13 dropouts were given. These data were excluded from further analysis.
Selective reporting (reporting bias)	Low risk	Reported all collected outcomes
Other bias	Low risk	Used multi‐variate analysis to examine ST depression to adjust for hypertension imbalance between 2 groups. All other participant characteristics and intraoperative surgical details were similar between groups.