Chan 2007.

Methods	RCT, parallel design
Participants	188 patients, ASA I ‐ III, scheduled for hand surgery Exclusion criteria: local anaesthetic allergy, local infection, coagulopathy, neurological upper limb disorder, psychiatric or cognitive disorder, history of substance abuse or opiate use
Interventions	Ultrasound (n = 64) versus ultrasound + nerve stimulation (n = 62) versus nerve stimulation (n = 62) Axillary brachial plexus block; 3 nerves targeted individually in each group (radial, ulnar, median); all groups received 21 ml 2% lidocaine with 1:200,000 epinephrine and 21 ml 0.5% bupivacaine (14 ml around each nerve) Ultrasound: linear 5 ‐ 12 MHz probe (Philips HDI 5000); endpoint ‐ local anaesthetic spread around each nerve Nerve stimulation (Stimuplex): pulse duration 0.1 msec, frequency 2 MHz; endpoint ‐ stimulation at < 0.5 mA Ultrasound + nerve stimulation: needle positioned with ultrasound, further needle positioning to obtain stimulation at < 0.5 mA; endpoint ‐ circumferential spread of local anaesthetic
Outcomes	Block procedure time (time from palpation of axillary artery/ultrasound application to end of LA injection) Adequacy of block (sensory block evaluated in each nerve distribution area using pinprick at 30 min) Supplementation (requirement for either general anaesthesia or rescue block) Complications
Notes	Multiple practitioners ‐ experience in technique not given, although some anaesthetists and some fellow/resident anaesthetists who were supervised Registered in clinicaltrials.gov
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random number table
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
Blinding of participants and personnel (performance bias): Patient discomfort	High risk	Not possible to blind anaesthetist, although use of "sham" equipment in order to ensure participant blinding
Blinding of outcome assessment (detection bias): adequacy of block, supplementation of block	High risk	Need for rescue block assessed by anaesthetist who was not blinded
Blinding of outcome assessment (detection bias): Complications	Unclear risk	No details of who assessed this, possibly anaesthetist
Blinding of outcome assessment (detection bias): time outcomes	Unclear risk	Assessed by an independent observer, although unclear whether blinded
Blinding of outcome assessment (detection bias): Patient discomfort	Low risk	Assessed during follow‐up telephone conversation ‐ participant blinded to group allocation
Incomplete outcome data (attrition bias) All outcomes	High risk	30 participants (14%) not included as surgery commenced before 30‐minute assessment. Still possible to collect some outcome data for these participants
Selective reporting (reporting bias)	Low risk	Protocol details published in clinicaltrials.gov. NCT 00221884. Outcomes appear to be reported
Baseline characteristics	Low risk	Age, gender, weight, height, BMI, surgical time. All comparable
Funding sources	High risk	Funding sources reported, to include supply of ultrasound equipment by manufacturers
Operator expertise	High risk	Some blocks performed by supervised residents, which would have increased time to perform block and would introduce bias for this outcome