Sites 2006.

Methods	RCT, parallel design
Participants	56 patients, ASA I ‐ III, scheduled for hand surgery Exclusions: < 18 years, pregnant, allergy to study drug
Interventions	Ultrasound perivascular approach (n = 28) versus transarterial approach (n = 28) Axillary brachial plexus block with 30 ml 1.5% lidocaine in both groups Ultrasound: 3 ‐ 12 MHz probe (Philips EnVisor); endpoint ‐ circumferential spread of local anaesthetic around artery Transarterial: local anaesthetic injected when no blood aspirated on either side of artery Separate musculocutaneous nerve block could be done at discretion of operator prior to study protocol (uncontrolled)
Outcomes	Block failure Time to perform block (time from completion of sterile preparation to withdrawal of needle) Supplementation rates (conversion to GA, supplementation or rescue block) Adequacy of block (sensory testing evaluated with ice bag in palm Neurological complications
Notes	7 practitioners performing blocks (3 trainees and 4 experienced) Musculocutaneous nerve block not controlled for and used at anaesthetist's preference 5 ml 1.5% lidocaine with 5 µg/ml epinephrine given to all participants for analgesia for tourniquet pain Study terminated early due to high level of block failure in transarterial group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Use of block randomization
Allocation concealment (selection bias)	Unclear risk	Sealed envelopes but no further details
Blinding of participants and personnel (performance bias):adequacy of block, need for supplementation	High risk	Not possible to blind anaesthetist
Blinding of participants and personnel (performance bias):Complications	High risk	Not possible to blind anaesthetist
Blinding of participants and personnel (performance bias): time outcomes	High risk	Not possible to blind anaesthetist/personnel
Blinding of outcome assessment (detection bias): adequacy of block, supplementation of block	Low risk	Block assessed by blinded observer. Upgrade to GA etc. made by anaesthetist or surgeon not aware of group allocation
Blinding of outcome assessment (detection bias): Complications	Unclear risk	No details of who assessed this outcome
Blinding of outcome assessment (detection bias): time outcomes	Low risk	Blinded research nurse
Incomplete outcome data (attrition bias) All outcomes	High risk	Trial stopped early due to high failure rate in transarterial group
Selective reporting (reporting bias)	Unclear risk	Outcomes reported despite early stopping. Published protocol not sought
Baseline characteristics	Low risk	Baseline characteristics comparable
Funding sources	High risk	Ultrasound equipment provided by manufacturer during trial
Operator expertise	High risk	Some blocks performed by a supervised resident, some by an experienced anaesthetist