Muehling 2009.

Methods	RCT Approved by the local ethics committee and written informed consent obtained from all patients clinicaltrials.gov identifier NCT 00615888 Setting: Germany Funding: unspecified
Participants	All patients admitted with indications for elective open repair of an infrarenal aortic aneurysm were eligible for the study
Interventions	Treatment group: TEA (T7 and T10) in PCEA with ropivacaine 0.2% and sufentanil 2 mcg/mL (n = 50). Used intraoperatively and postoperatively for an unspecified duration Control group: IV PCA with piritramide (n = 49) General anaesthesia for all participants
Outcomes	Hospital LOS
Notes	Study authors contacted on 21 July 2014, for additional information but did not reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"randomized block design prepared by the Department of Biometry, University of Ulm"
Allocation concealment (selection bias)	Unclear risk	"After they gave written informed consent, patients were randomly assigned"
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	One participant in each group withdrew written informed consent and was excluded, leaving 50 participants in the traditional group and 49 in the fast‐track group, who were studied in an intention‐to‐treat
Selective reporting (reporting bias)	Low risk	All results reported
Other bias	Unclear risk	Other treatment modalities differ between the 2 groups as per protocol Analysed in intention‐to‐treat