Appendix 1. MEDLINE (OvidSP) search strategy

1. (ultrasound adj5 guidanc*).mp.

2. exp Nerve Block/ or exp Anesthesia, Local/ or exp Anesthesia, Spinal/ or ((central or spinal or epidural or caudal or neuraxial or peripheral) adj5 nerve block*).mp. or (nerv adj3 block*).ti,ab. or (regional adj5 (an?est* or techniq*)).mp. and (child* or neanat* or preschool* or adolescent*).af.

3. ((randomized controlled trial or controlled clinical trial).pt. or randomized.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab. or (meta?analysis or review or systematic review).mp.) not (animals not (humans and animals)).sh.

4. 1 and 2 and 3