Appendix 1. Publication Bias Diagrams

Funnel plot of the publication bias of the overall catheterization success
    analysis

Fig. A1.1. Funnel plot of the publication bias of the overall catheterization success analysis

Funnel plot of the publication bias of the catheterization success analysis on
    the first attempt

Fig. A1.2. Funnel plot of the publication bias of the catheterization success analysis on the first attempt

Funnel plot of the publication bias of the complexity development analysis

Fig. A1.3. Funnel plot of the publication bias of the complexity development analysis


Appendix 2. Certainty of evidence using the GRADE method

Reliability assessment Number of patients Effect Result Importance
number of studies study design risk of bias inconsistency indirection inaccuracy other US AL relative
(95% CI)
First Attempt Success (CV)
10 RCT Expressed NE NE NE No 614/763
(80.5 %)
378/702
(53.8 %)
RR 1.52
(1.18–1.95)
⚪ ⚪ ⚫ ⚫
Low
Unimportant
Overall Success (CV)
11 RCT Expressed NE NE NE No 792/830
(95.4 %)
665/771
(86.3 %)
RR 1.11
(1.03–1.20)
⚪ ⚪ ⚫ ⚫
Low
Unimportant
Complications (CV)
10 RCT NE NE NE Expressed No 51/786
(6.5 %)
165/730
(22.6 %)
RR 0.3
(0.23–0.41)
⚪ ⚪ ⚪ ⚫
Moderate
Important
Pneumothorax (CV)
9 RCT NE NE NE NE No 0/604
(0.00 %)
7/542
(1.29 %)
RR 0.19
(0.04–0.84)
⚪ ⚪ ⚪ ⚪
High
Important
Arterial puncture (CV)
10 RCT NE NE NE NE No 26/715
(3.64 %)
105/722
(14.5 %)
RR 0.26
(0.18–0.40)
⚪ ⚪ ⚪ ⚫
Moderate
Important
Hematoma (CV)
10 RCT Expressed NE NE NE No 12/714
(1.68 %)
47/713
(6.59 %)
OR 0.30
(0.17–0.52)
⚪ ⚪ ⚪ ⚫
Moderate
Important
Overall Success (PV)
5 RCT Expressed Expressed NE NE No 873/1019
(85.7 %)
745/994
(74.9 %)
OR 1.22
(1.09–1.35)
⚪ ⚪ ⚫ ⚫
Low
Unimportant
Table A2.1. Certainty of evidence using the GRADE method Note: CI — confidence interval; OR — odds ratio; RR — risk ratio; US — ultrasound; AL — anatomical landmarks; CV — central veins; PV — peripheral veins; NE — not expressed.