Liu 2012

Methods	Randomized controlled trial Approved by the ethics committee; written parental informed consent obtained Setting: China Funding: unspecified Date of collection: not reported
Participants	102 ASA 1 or 2 paediatric patients from 1 month to 8 years of age and scheduled for urological or perineal surgery Children with pulmonary, neurological or coagulation dysfunction; history of multiple surgeries; spinal or sacral malformation or skin abnormalities were excluded
Interventions	Treatment group: caudal anaesthesia with ultrasound for pre‐scanning; positive reaction in caudal space was monitored simultaneously by ultrasound (n = 52) Control group: caudal anaesthesia with landmarks; positive reaction in caudal space was monitored simultaneously by classic swoosh test (n = 50) All blocks performed under general anaesthesia with sevoflurane and loss of resistance to air. Mixture of 0.5% or 1.0% lidocaine and 0.125% to 0.250% levobupivacaine 0.5 to 1.0 mL /kg was injected. Sevoflurane was closed and was replaced with midazolam or a propofol infusion thereafter. The surgical incision was performed 10 to 15 minutes later. Children with block failures were operated while under general anaesthesia
Outcomes	Success: If 4 consecutive attempts still failed to reach the caudal space, the puncture would be given up; this was regarded as failure of caudal block Time to perform the procedure Number of attempts
Notes	Translated in English
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"randomly divided random number table"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel	High risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
Selective reporting (reporting bias)	Low risk	All results provided
Other bias	Low risk	Groups well balanced