Comparison of two transducers for ultrasound-guided vascular access in long axis.

The long-axis technique for ultrasound-guided vascular access may benefit users attempting deeper targets. The purpose of this study was to determine if a difference exists in the difficulty experienced by novice ultrasound users in obtaining vascular access in long axis with linear vs. curvilinear transducers. Subjects obtained access on simulated peripheral veins in a gel model. Time to successful cannulation, number of surface breaks, and number of needle redirects was recorded. Statistical methods used include analysis of variance, regression analysis, and negative binomial regression. The study population was a convenience sample of 24 4th-year medical students, Emergency Medicine residents, attendings, and nurses, and off-service residents rotating in the Emergency Department who had performed less than three ultrasound-guided vascular access procedures. The difference between the number of surface breaks and redirects and the perceived difficulty between the linear and curvilinear transducers was statistically significant (p = 0.002, p = 0.049, p = 0.04). The difference in time to cannulation with the linear and curvilinear transducers was not statistically significant. Novice ultrasound users found the curvilinear transducer easier to use for simulated vascular access in the long axis. Studies utilizing live patients and more experienced ultrasonographers could determine whether the preference for the curvilinear transducer amounts to clinically meaningful shorter times to needle entry and more successful first attempts.