Needle tip visualization during ultrasound-guided vascular access: short-axis vs long-axis approach

Ultrasound guidance for central venous catheterization improves success rates and decreases complications when compared to the landmark technique. Prior research has demonstrated that arterial and/or posterior vein wall puncture still occurs despite real-time ultrasound guidance. The inability to maintain visualization of the needle tip may contribute to these complications. This study aims to identify whether long-axis or short-axis approaches to ultrasound-guided vascular access afford improved visibility of the needle tip.

A prospective trial was conducted at a level I trauma center with an emergency medicine residency. Medical students and residents placed needles into vascular access tissue phantoms using long-axis and short-axis approaches. Ultrasound images obtained at the time of vessel puncture were then reviewed. Primary outcome measures were visibility of the needle tip at the time of puncture and total time to successful puncture of the vessel.

All subjects were able to successfully obtain simulated blood from the tissue phantom. Mean time to puncture was 14.8 seconds in the long-axis group and 12.4 seconds in the short-axis group (P = .48). Needle tip visibility at the time of vessel puncture was higher in the long-axis group (24/39, 62%) as opposed to the short-axis group (9/39, 23%) (P = .01).

In a simulated vascular access model, the long-axis approach to ultrasound-guided vascular access was associated with improved visibility of the needle tip during vessel puncture. This approach may help decrease complications associated with ultrasound-guided central venous catheterization and should be prospectively evaluated in future studies.