Zhefeng 2019.

Study characteristics
Methods	Single‐centre prospective randomised controlled 2‐arm study, with blinding not described China Duration: March 2018 to May 2018
Participants	77 participants randomised (experimental = 39, comparator = 38) 77 participants analysed mean age (years) ± SD: 46.2 ± 8.4 experimental, 49.1 ± 8.2 comparator gender (male/female): 29/10 experimental, 26/12 comparator severity of condition (experimental/comparator): ASA 2 24/21, ASA 3 15/17 comorbidities (experimental/comparator): not reported body weight (kg): 67.1 ± 9.0 experimental, 65.4 ± 9.9 comparator height (cm): 166.1 ± 7.1 experimental, 167.2 ± 7.3 comparator artery of interest: radial diameter (mm), mean ± SD: 2.4 ± 0.3 experimental, 2.5 ± 0.4 comparator. Catheter size not described catheterisation purpose (experimental/comparator): all for diagnosis (pressure monitoring or blood test, % not reported, during elective surgery) Inclusion criteria scheduled to undergo elective hepatectomy or splenectomy with general anaesthesia between 18 and 60 years of age body weight 50 to 85 kg ASA 2 or 3 Exclusion criteria negative Allen’s test peripheral vascular disease ulnar artery occlusion haemorrhagic shock atherosclerosis morbid obesity unstable angina Raynaud’s disease cardiogenic shock diabetes hypertension previous multiple arterial punctures
Interventions	Experimental: ultrasound‐guided RA puncture (real‐time; artery short axis, out‐of‐plane) Comparator: modified ultrasound‐guided RA puncture (real‐time; artery short axis, out‐of‐plane with add of a developing line) Level of experience of person carrying out the procedure: quote: "all radial artery punctures were performed by interns who were in the anesthesiology rotation" Concomitant medications: all participants under general anaesthesia: quote: "patients were placed in supine position and administrated 0.05 mg/kg midazolam and 0.1 μg/kg sufentanil for analgesia and sedation" and "2% lidocaine was used for local anaesthesia" Excluded medications: not reported
Outcomes	Primary (specified) first‐attempt success rate Primary (collected) first‐attempt success rate Secondary (specified) ultrasound localisation time puncture time cannulation time Secondary (collected) ultrasound localisation time puncture time cannulation time complications (vasospasm, haematoma, thrombosis, occlusion, aneurysm) Time points reported: up to 1 day and up to 2 days after the procedure
Notes	Funding: quote: "supported by Beijing Municipal Science and Technology Commission (no. Z171100001017036)" Conflicts of interest: quote: "none" Protocol (ChiCTR1800015337) available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly assigned to traditional ultrasound or ultrasound with developing line groups using a sealed envelope"
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "the limitations of this study include the lack of a double‐blind study design"
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "the limitations of this study include the lack of a double‐blind study design"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "there were no drop‐outs during the trial"
Selective reporting (reporting bias)	Low risk	All planned outcomes were reported
Other bias	Low risk	We do not suspect any other bias related to this study

AA = axillary artery; ABGA = arterial blood gas analysis; AD = angle‐distance; ASA = Amerian Society of Anesthesiologists physical status classification system; BMI = body mass index; CA = coronary angiography; DNTP = dynamic needle tip positioning; DPA = dorsalis pedis artery; ENT = ear, nose, and throat speciality; GA = general anaesthesia; ICU = intensive care unit; INR = international normalised ratio; IP = in‐plane; ITT = intention‐to‐treat; IU = international unit; LA = long axis; OA = oblique axis; PCI = percutaneous coronary intervention; PVD = peripheral vascular disease; RA = radial artery; SA = short axis; SD = standard deviation; US = ultrasound; VAS = visual analogue scale.