Selby 1995.

Methods	Randomized controlled 4‐arm parallel trial at a metropolitan hospital in the UK
Participants	160 unpremedicated women, American Society of Anesthesiologists (ASA) grade 1 or 2, requiring insertion of an intravenous cannula for general anaesthetic Excluded if allergies to local anaesthetics, or analgesic medication taken in last 4 hours Groups (40 in each) were similar in terms of age, weight, visibility of veins and anxiety levels
Interventions	Group 1: no local anaesthetic Group 2: 0.2 mL of EMLA cream rubbed into the skin over the vein and covered with a non‐absorbent dressing for 5 minutes before cannulation Group 3: ethyl chloride sprayed over the vein for 10 seconds from a height of 20 cm, with cannulation performed immediately Group 4: 0.2 mL of 1% lignocaine injected subcutaneously at the site of venepuncture with a 25 gauge (G) needle, and left for 30 seconds before cannulation
Outcomes	Anxiety, difficulty of cannulation, number of failed cannulations, pain during local anaesthetic application, pain of cannulation, pain 1 minute after cannulation
Funding	None declared
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Randomly allocated" Method not described
Allocation concealment (selection bias)	Unclear risk	Method not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Manuscript reports 2 different set of figures for the first attempt success rate. This ranged from 38 to 40 out of 40 for the control group, and from 36 to 37 for the ethyl chloride group
Selective reporting (reporting bias)	Unclear risk	Protocol not described, but all expected outcomes described
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding
Blinding of outcome assessment (detection bias) All outcomes	High risk	No blinding