Rose 2018.

Study characteristics
Methods	[Abstract of event] Single‐centre prospective randomised controlled 2‐arm open‐label study Site and duration not reported
Participants	60 participants randomised (experimental = 30, comparator = 30) 60 participants analysed mean age (years) ± SD: not reported gender (male/female): not reported severity of condition (experimental/comparator): not reported comorbidities (experimental/comparator): not reported body weight (kg): not reported artery of interest: radial diameter (mm), mean ± SD: not reported. Catheter size not reported catheterisation purpose (experimental/comparator): all for diagnosis (pressure monitoring or frequent blood test) Inclusion criteria 18 years of age or older at a tertiary care urban academic emergency department requiring radial catheter placement for continuous blood pressure monitoring or frequent blood draws Exclusion criteria contraindications to radial arterial access pre‐existing arterial catheter at alternative site
Interventions	Experimental: ultrasound‐guided RA puncture (real‐time, artery axis and needle plane not described) Comparator: RA puncture by palpation and landmarks Level of experience of person carrying out the procedure: quote: "performed by emergency medicine residents with standard ultrasound training" Concomitant medications: not reported Excluded medications: not reported
Outcomes	Primary (specified) number of attempts duration of procedure resident experience complication rate Primary (collected) number of attempts duration of procedure resident experience complication rate successful radial arterial line rate Secondary (specified) no differentiation between primary and secondary outcomes Secondary (collected) no differentiation between primary and secondary outcomes Time points reported: up to the end of the procedure (not described)
Notes	Funding: not described Conflicts of interest: not described Protocol not available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described Quote: "patients were randomized"
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not described, but due to the nature of the interventions, we assumed that blinding of personnel was not possible
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were no losses
Selective reporting (reporting bias)	High risk	Baseline characteristics between groups and safety outcomes were planned but were reported only by descriptions (i.e. without numerical values) for each group
Other bias	Low risk	We do not suspect any other bias related to this study