Norman 1997.

Methods	RCT Approved by the ethics committee and written informed consent obtained from all patients Setting: United States of America Funding: unspecified
Participants	42 male patients undergoing elective abdominal aortic replacement
Interventions	Treatment group: TEA (T9‐T10 or T10‐T11) with bupivacaine intraoperatively only and morphine thereafter (n = 22) Control group: IV PCA with morphine (n = 20) General anaesthesia for all participants
Outcomes	Hospital LOS
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomized", no details
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	Three participants eliminated for protocol violation
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Unclear risk	Groups well balanced Not in intention‐to‐treat: 2‐failed epidurals excluded