Investigators hypothesized that （1） various ultrasound-guided methods had different performances of vascular puncture and catheterization, (2) certain risk factors influenced safety and success rate of vascular puncture and catheterization (3) implementation of protocols could improve the performances of ultrasound-guided vascular puncture and catheterization.
To assess and improve the safety and success rate of vascular puncture and catheterization using ultrasound-guided methods.