Results
The central vein was successfully cannulated in all 256 participants (163 [64%] man and 93 [36%] women; mean age 69 ± 19 [range 13–104 years]), including 182 and 74 who underwent internal jugular vein cannulation (IJVC) and femoral vein cannulation (FVC), respectively. The incidence of successful puncture on the first attempt was higher in the biplane group than that in the single-plane group (91.6% vs. 74.7%; relative risk (RR), 1.226; 95% confidence interval (CI), 1.069–1.405; 