Tenling 1999.

Methods	Parallel RCT Ethics committee: approved by the ethics committee of Uppsala University Informed consents: obtained Site: Uppsala, Sweden Setting: university hospital Dates of data collection: not reported Funding: the study was supported by grants from the Swedish Medical Research Council (5315), the E. K. G. Selander Foundation, the Uppsala County Association Against Heart and Lung Diseases, and Uppsala University Registration: unspecified
Participants	29 participants: mean age: 61.6 years; sex distribution: 1 female and 28 males Inclusion criteria Patients scheduled for CABG Stable angina pectoris LVEF > 40% Exclusion criteria Significant lung, kidney, liver, or neurological disease Insulin‐dependent diabetes mellitus Significant valve disease or bleeding diathesis Receiving heparin or heparin fragments
Interventions	Intervention Epidural analgesia (N = 14) Comparator Systemic analgesia (N = 14) Premedication: morphine and scopolamine Induction: fentanyl, thiopental, and pancuronium Maintenance: nitrous oxide, isoflurane, and fentanyl or epidural analgesia Surgery: CABG with CPB
Outcomes	Relevant to this review Risk of mortality Tracheal extubation Others Ventilation/perfusion mismatch
Notes	Correspondence: letter sent 16 March 2018; no reply Conflict of interest: none reported DOI: n/a
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomization was achieved with sealed envelopes"
Allocation concealment (selection bias)	Low risk	Sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "unblinded"
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "unblinded"
Incomplete outcome data (attrition bias) All outcomes	Low risk	One participant was excluded from the analyses (reoperation)
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Low risk	Not in intention‐to‐treat Groups had similar demographic data