Randomised controlled trials (RCTs) that compared ultrasonography to traditional, adjunctive modalities or that compared stimulating to non-stimulating catheters were included. Studies had to report blinded outcome assessment and appropriate sample size justification to be included.
Interventions in the included ultrasonography studies consisted of ultrasonography-guided axillary, lateral sciatic or femoral (with and without subgluteal/popliteal sciatic block) nerve blocks. Comparator groups consisted of trans-arterial technique and neurostimulation. The number of injections ranged from one to four. Trials included patients undergoing surgery of the forearm, wrist, hand, ankle, and lower extremities and knee arthroscopy. Outcomes reported were incidence of side effects, surgery failure, success rate, time to readiness for surgery, minimal effective volume to block the nerve in 50% of patients, number of attempts, and duration of sensory block. One trial included children; details on included patient ages were not reported for other trials.
Catheter trials compared stimulating and blind catheters for interscalene, femoral, and posterior popliteal sciatic blocks. They assessed patients undergoing shoulder surgery, total knee replacement, anterior cruciate ligament repair, hallux valgus repair or healthy volunteers. Outcomes reported were functional outcome at six weeks (Constant Murley Score), block success, local anaesthetic volume required to achieve adequate analgesia, onset of sensory block, consumption of rescue opioids, local anaesthetic consumption and pain score (visual analogue scale 0 to 100).
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.