Weiner 2013.

Study characteristics
Methods	Randomised, open‐label trial
Participants	Setting: ED Number of participants: 53 (USG 30, LM 23) Age, mean (SD) years: USG 46.2 (14.6), LM 53 (14.2) Difficulty: difficult (had a history of difficult IV cannulation, or at least 2 failed attempts with LM) Sites of peripheral veins: upper extremity
Interventions	Technique LM vs USG: Machine: Zonare z.one ultra Convertible Ultrasound System (Zonare) with a 8‐3 MHz probe, or Sonosite M‐turbo (Sonosite) with a 13‐6 MHz probe Axis: short Guidance: dynamic Operator Profession: nurse Number of operators: not specified Experience of USG before the study: no 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: not specified Needle Length: up to operators' discretion Gauge: 18 ‐ 20
Outcomes	First‐pass success of cannulation, overall success of cannulation, procedure time for overall cannulation, number of attempts, pain, patient satisfaction Definition of successful cannulation: blood return from a catheter, and no signs of extravasation Definition of start and end of time measurement: Start: a nurse was informed of the result of randomisation  End: intravenous access was achieved
Funding	Not specified
Declarations of interest	Not specified
Notes	Data for first‐pass success of cannulation and patient satisfaction were unpublished and obtained through communication with an author (SW)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Initially a computerised coin‐toss, later randomised by shuffling sealed envelopes
Allocation concealment (selection bias)	Low risk	Initially a computerised coin‐toss, later randomised by shuffling 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) Pain	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) Procedure time for overall 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) Number of attempts	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) Patient satisfaction	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	There were only 3 dropouts (USG 1, LM 2)
Incomplete outcome data (attrition bias) Overall success of cannulation	Low risk	There were only 3 dropouts (USG 1, LM 2)
Incomplete outcome data (attrition bias) Pain	Low risk	There were only 3 dropouts (USG 1, LM 2)
Incomplete outcome data (attrition bias) Procedure time for overall cannulation	Low risk	There were only 3 dropouts (USG 1, LM 2)
Incomplete outcome data (attrition bias) Number of attempts	Low risk	There were only 3 dropouts (USG 1, LM 2)
Incomplete outcome data (attrition bias) Patient satisfaction	Low risk	There were only 3 dropouts (USG 1, LM 2)
Selective reporting (reporting bias)	Low risk	The outcomes reported in the article were consistent with the trial registry (NCT01439113)
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 Pain	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
Overall risk Patient satisfaction	High risk	At least one domain was at high risk

BMI: body mass index
ED: emergency department
ICU: intensive care unit
IV: intravenous
LM: landmark method
SD: standard deviation
USG: ultrasound guidance