Nishizawa 2020.

Study characteristics
Methods	Randomised, open‐label trial
Participants	Setting: ICU Number of participants: 60 (USG 30, LM 30) Age, mean (SD) years: USG 74.2 (14.7), LM 79.4 (10.8) Difficulty: difficult (at least 2 failed attempts with LM, or at least 2 experienced nurses anticipated difficulty with LM based on the absence of a palpable vein or a history of difficult IV cannulation) Sites of peripheral veins: upper extremity
Interventions	Technique LM vs USG: Machine: Noblus (Hitachi) with a 10‐5 MHz probe Axis: short Guidance: dynamic Operator Profession: nurse Number of operators: 30 Experience of USG before the study: no Length of experience with USG before the study: none A training programme of USG for the study: yes Number of clinical cases with USG required or experienced before the study intervention started: 3 Needle Length: 31 or 51 mm Gauge: 20
Outcomes	First‐pass success of cannulation, overall success of cannulation, complications Definition of successful cannulation: blood return from a catheter, saline flush without signs of extravasation
Funding	None
Declarations of interest	None declared
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random sequence was created by a computer
Allocation concealment (selection bias)	Low risk	Concealed using opaque, sealed envelopes
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. One of the co‐authors assessed the outcome
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. One of the co‐authors assessed the outcome
Blinding (performance bias and detection bias) Overall complications	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. One of the co‐authors assessed the outcome
Incomplete outcome data (attrition bias) First‐pass success of cannulation	Low risk	The outcome was available for all participants
Incomplete outcome data (attrition bias) Overall success of cannulation	Low risk	The outcome was available for all participants
Incomplete outcome data (attrition bias) Overall complications	Low risk	The outcome was available for all participants
Selective reporting (reporting bias)	Low risk	The outcomes reported in the article were consistent with the trial protocol (obtained through communication with an author (TN))
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 Overall complications	High risk	At least one domain was at high risk