Strub 2011.

Methods	RCT, parallel design
Participants	141 patients scheduled for hand surgery distal to the elbow with and estimated duration < 2 hrs Excluded: Those that declined to give informed consent, had known allergy to any anaesthetic substance, an infection in region of injection site, severe coagulopathy, pathological enlargement of axillary lymph nodes, those who had had previous surgery on the axilla
Interventions	Ultrasound (n = 70) vs landmark technique (n = 71) Axillary brachial plexus block; dose of 20 ml LA deposited behind artery next to radial nerve; 10 ml LA then injected around mediocranial median nerve and mediocaudal ulnar nerve Ultrasound: cross‐section of axillary artery is imaged. Individual nerves are then identified. Cannula introduced under US. 20 G 105” bevelled needle. LA injected around all 4 nerves individually starting with radial nerve. Aim of infiltration is to see a circular perineural spread of the fluid in the ultrasound image. Bupivacaine hydrochloride (5 mg/ml) with 0.5% adrenaline and mepivacaine hydrochloride (10 mg/ml) in a ratio of 1:1 Neurostimulation: Anatomic landmarks used for orientation. Needle inserted in space between axillary artery and coracobrachial muscle, near to axillary fold. Needle at an angle to skin of 50 ‐ 90°, inserted past facial click and advanced cranially, caudally or transarterially past axillary artery
Outcomes	Supplementation rate (blocks which required additional anaesthesia, analgesics or GA) Complications Time to perform block (no definition)
Notes	Training had been given to those conducting the ultrasound technique; baseline of 10 procedures with US before study, or 300 in conventional technique Not possible to combine data for Time to perform block or Onset time as no standard deviation reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random numbers
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias):Complications	High risk	Surgeon not blinded
Blinding of participants and personnel (performance bias): time outcomes	High risk	Surgeon not blinded
Blinding of outcome assessment (detection bias): adequacy of block, supplementation of block	High risk	“No blinding” reported at end of discussion
Blinding of outcome assessment (detection bias): Complications	High risk	“No blinding” reported at end of discussion
Blinding of outcome assessment (detection bias): time outcomes	High risk	“No blinding” reported at end of discussion
Incomplete outcome data (attrition bias) All outcomes	Low risk	No apparent losses
Selective reporting (reporting bias)	Unclear risk	Published protocol not sought
Baseline characteristics	Low risk	All comparable
Funding sources	Low risk	None
Operator expertise	High risk	Surgeon with limited experience (10 previous attempts) using ultrasound technique