Bridey 2018.

Study characteristics
Methods	Randomised, open‐label trial
Participants	Setting: ICU Number of participants: 114 (USG 57, LM 57) Age, mean (SD) years: USG 65.5 (17.6), LM 64 (17) Difficulty: difficult (could not see and palpate a vein) Sites of peripheral veins: upper extremity
Interventions	Technique LM vs USG: Machine: Sonosite M‐turbo (Sonosite) with a high‐frequency linear transducer Axis: not specified Guidance: not specified Operator Profession: ED registered nurse Number of operators: 20 Experience of USG before the study: 70% of the operators had previous experience Length of experience with USG before the study: not specified A training programme of USG for the study: yes Number of clinical cases with USG required or experienced before the study intervention started: 10 Needle Length: 29 mm Gauge: not specified
Outcomes	First‐pass success of cannulation, overall success of cannulation, number of attempts, patient satisfaction Definition of successful cannulation: smooth normal saline flush, and no signs of extravasation
Funding	The French Intensive Care Society, ‘Bourse Recherche Paramédicale 2016’
Declarations of interest	None declared
Notes	Although IV cannulation was attempted for four days in this study, we used results from day one to align with the conditions in other studies
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The randomisation list was computer‐generated (this was not stated in the article, but obtained through communication with an author (AK))
Allocation concealment (selection bias)	Low risk	Randomisation with varying block sizes, sealed and opaque envelopes (this was not stated in the article, but obtained through communication with an author (AK))
Blinding (performance bias and detection bias) First‐pass success of cannulation	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves (this was not stated in the article, but obtained through communication with an author (AK))
Blinding (performance bias and detection bias) Overall‐success of cannulation	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves (this was not stated in the article, but obtained through communication with an author (AK))
Blinding (performance bias and detection bias) Number of attempts	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves (this was not stated in the article, but obtained through communication with an author (AK))
Blinding (performance bias and detection bias) Patient satisfaction	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves
Incomplete outcome data (attrition bias) First‐pass success of cannulation	Low risk	There were only three dropouts (USG 1, LM 2), and the reasons were detailed
Incomplete outcome data (attrition bias) Overall success of cannulation	Low risk	There were only two dropouts (USG 1, LM 1), and the reasons were detailed
Incomplete outcome data (attrition bias) Number of attempts	Low risk	There were only three dropouts (USG 1, LM 2), and the reasons were detailed
Incomplete outcome data (attrition bias) Patient satisfaction	High risk	There were 10 dropouts from the assessment (USG 5, LM 5), and the reasons were not detailed
Selective reporting (reporting bias)	Low risk	The outcomes reported in the article were consistent with the trial registry (NCT02285712)
Other bias	Low risk	No concerns about other sources of bias
Overall risk First‐pass success of cannulation	High risk	At least one domain was at high risk
Overall risk Overall success of cannulation	High risk	At least one domain was at high risk
Overall risk Number of attempts	High risk	At least one domain was at high risk
Overall risk Patient satisfaction	High risk	At least one domain was at high risk