Objective To compare the success rate and safety of the short-axis (SAX) approach and long-axis (LAX) approach to ultrasound-guided central venous cannulation.Methods Electronic bibliographic databases including PubMed,Cochrane Library,Science Direct,and Web of Science were searched for randomized controlled trials comparing ultrasound-guided central venous cannulation via the LAX and SAX approaches published during the period from January,2011 to October,2017.We extracted the data from the eligible studies and assessed the first-attempt success rate,overall puncture success rate and complication rate of the two approaches.The relative risk (RR) with the 95％ CI was calculated using a fixed or random effects model.Results Seven randomized controlled trials were included for meta-analysis.The results showed that the first-attempt success rate was significantly higher in the SAX group than in the LAX group (RR=1.27,95％CI:1.11-1.46;P=0.0005,I2=49％),but the overall puncture success rate did not differ significantly between the two approaches (RR=1.04,95％ CI:0.97-1.10;P=0.27,I2=84％).The incidence of accidental arterial puncture with the SAX approach was significantly lower than that with the LAX approach (RR=1.04;95％CI:1.01-1.08;P=0.01,I2=30％).Conclusion Ultrasound-guided central venous cannulation via the SAX approach,as compared with the LAX approach,can increase first-attempt success rate and reduce the incidence of accidental arterial puncture.

Objective To compare the success rate and safety of the short-axis (SAX) approach and long-axis (LAX) approach to ultrasound-guided central venous cannulation.Methods Electronic bibliographic databases including PubMed,Cochrane Library,Science Direct,and Web of Science were searched for randomized controlled trials comparing ultrasound-guided central venous cannulation via the LAX and SAX approaches published during the period from January,2011 to October,2017.We extracted the data from the eligible studies and assessed the first-attempt success rate,overall puncture success rate and complication rate of the two approaches.The relative risk (RR) with the 95％ CI was calculated using a fixed or random effects model.Results Seven randomized controlled trials were included for meta-analysis.The results showed that the first-attempt success rate was significantly higher in the SAX group than in the LAX group (RR=1.27,95％CI:1.11-1.46;P=0.0005,I2=49％),but the overall puncture success rate did not differ significantly between the two approaches (RR=1.04,95％ CI:0.97-1.10;P=0.27,I2=84％).The incidence of accidental arterial puncture with the SAX approach was significantly lower than that with the LAX approach (RR=1.04;95％CI:1.01-1.08;P=0.01,I2=30％).Conclusion Ultrasound-guided central venous cannulation via the SAX approach,as compared with the LAX approach,can increase first-attempt success rate and reduce the incidence of accidental arterial puncture.