Aponte 2007.

Study characteristics
Methods	Randomised, open‐label trial
Participants	Setting: operating room Number of participants: 35 (USG 19, LM 16) Age, mean (SD) years: USG 55.5 (15.7), LM 57.3 (18.9) Difficulty: difficult (participants reported past difficulties or anaesthesia providers identified them as having the potential for difficulty) Sites of peripheral veins: upper extremity
Interventions	Technique LM vs USG: Machine: Site‐Rite 3 Ultrasound Unit (Bard Access Systems) with a 9.0 MHz probe Axis: not specified Guidance: dynamic Operator Profession: certified registered nurse anaesthetist Number of operators: two Experience of USG before the study: yes 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: 5 Needle Length: not specified Gauge: 18 ‐ 22
Outcomes	First‐pass success of cannulation, overall success of cannulation, procedure time for first‐pass cannulation, procedure time for overall cannulation, number of attempts Definition of successful cannulation: blood return from a catheter Definition of start and end of time measurement Start: USG, a transducer was placed onto the skin, and a vein was identified on the ultrasound monitor LM, a nurse started identifying potential target veins End: successful intravenous cannulation
Funding	Not specified
Declarations of interest	Not specified
Notes	We attempted to contact the authors to obtain additional information but were unable to reach them.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No description of randomisation process
Allocation concealment (selection bias)	Unclear risk	No description of allocation concealment process
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
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
Blinding (performance bias and detection bias) Procedure time for first‐pass cannulation	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves
Blinding (performance bias and detection bias) Procedure time for overall cannulation	High risk	Blinding of participants and operators is impossible due to the nature of the intervention. Operators assessed the outcome themselves
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
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) Procedure time for first‐pass cannulation	High risk	The outcome was evaluated only for participants with successful cannulation
Incomplete outcome data (attrition bias) Procedure time for overall cannulation	Low risk	The outcome was available for all participants
Incomplete outcome data (attrition bias) Number of attempts	Low risk	The outcome was available for all participants
Selective reporting (reporting bias)	Unclear risk	No study register or protocol was available
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 Procedure time for first‐pass cannulation	High risk	At least one domain was at high risk
Overall risk Procedure time for overall 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