Armstrong 1993.

Methods	Prospectively quasi‐randomized trial All internal jugular vein cannulations performed over a period of 6 weeks were assessed. The ‘SiteRite’ was used exclusively in one operating theatre. and cannulations in the other were performed in a standard manner using anatomical landmarks alone
Participants	Patients before operations Inclusion and exclusion criteria not clearly defined in the text Treatment and control groups not adequately described at study entry 3 admission details described (sex, weight, height) Admission details not described, only “equal demographic data”: __X__ Participants anaesthetized Operators: number: no details   Experience: anaesthetists of registrar grade or above
Interventions	Technique: LM: finder needle used  vs US: ultrasound with 7.5‐MHz resolution (SiteRite scanner) without needle guide, finder needle used. (After skin cleaning and draping, the internal jugular vein was located with a 21 G needle. After  the  internal  jugular  vein was located, an 18‐gauge cannula was inserted with the initial needle acting as a guide. A guide wire was then inserted through the cannula) ((short axis) see typical image in the article) LM Unclear whether direct or indirect puncture Technique standardized: unclear Head down (Trendelenburg), head rotation Seldinger technique Vessel and side: IJV right side US Indirect puncture Technique standardized: unclear Head down (Trendelenburg), head rotation Seldinger technique Vessel and side: IJV right side
Outcomes	Overall success rate (N, %) in 100 seconds Failure rate (N, %) Number of attempts until success (N, SD) Complication rate: total, arterial puncture, local bleeding, haematoma formation, cardiac complications, malpositioned catheter tips, rate of catheter‐related infection, mortality, rate of other complications (thrombosis, embolism, haematomediastinum and hydromediastinum, haematothorax and hydrothorax, pneumothorax, subcutaneous emphysema, nerve injury) (n, %) Time to successful cannulation (seconds) (time from initial skin palpation immediately before initial needle insertion to removal of the 18‐gauge cannula from the guide wire). In cases for which the internal jugular vein was not located, cannulation times were disregarded Success with attempt number 1 (N, %)
Notes	No cross‐over landmark‐guided puncture or ultrasound‐guided puncture 5 insertions into the right internal jugular vein were abandoned in the control group. In 3 individuals, the vein was not located, and later use of the ‘SiteRite’ demonstrated very small veins adjacent to the carotid artery. In one case, a cannula had been inserted but was shown to be outside the vein when examined using the ‘SiteRite’; in the fifth case, the carotid artery was punctured by the seeking needle and the procedure abandoned
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomization method: no details
Allocation concealment (selection bias)	Unclear risk	Randomization method: no details
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Subject blinded: Unclear__X__ Physician blinded: No__X__ Outcome assessor blinded: Unclear__X__
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcomes of participants who withdrew or were excluded after allocation were EITHER detailed separately OR included in an intention‐to‐treat analysis OR the text stated no withdrawals
Selective reporting (reporting bias)	Low risk	Yes
Other bias	High risk	Participant selection: Yes _X_ Withdrawals: Unclear _X_ Postrandomization exclusion: No _X_ Intention‐to‐treat analysis: Unclear _X_
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Subject blinded: Unclear__X__ Physician blinded: No__X__
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessor blinded: Unclear__X__
Treatment and control groups were adequately described at entry.	High risk	No