Ultrasound Guidance Versus Landmark-Guided Palpation for Radial Arterial Line Placement by Novice Emergency Medicine Interns: A Randomized Controlled Trial

J Emerg Med. 2020 Dec;59(6):911-917. doi: 10.1016/j.jemermed.2020.07.029. Epub 2020 Sep 8.


Background: More than 10 million arterial lines are placed annually worldwide, many of which happen in the emergency department. Before the introduction of point-of-care ultrasound, landmark-guided palpation (LMGP) was considered standard of care.

Objective: The objective of this study is to compare ultrasound-guided (USG) and LMGP of radial arterial line cannulation by novice emergency medicine interns.

Methods: This was a single-center, prospective, randomized controlled trial (NCT03326739) of a convenience sample of adult patients who presented to an urban, university hospital with 100,000 visits annually. There was no funding for this study. Patients who required an arterial line were blindly randomized into LMGP or USG groups. Only novice emergency medicine interns, defined as interns with <15 previous placements, who were not blinded, performed the cannulation. Statistical analyses included t and Fisher exact tests.

Results: Forty patients were enrolled with 20 patients randomized to each group. USG had a first-pass success of 75% vs. 0% for LMGP (p < 0.00001) and an overall success of 100% vs. 15% for LMGP (p < 0.00001), a mean of 1.30 attempts vs. 2.95 attempts for LMGP (a difference of 1.65; p < 0.0001), and a mean time for placement of 264 s vs. 524 s for LMGP (a difference of 260; p = 0.0025). Of the failed LMGP, USG crossover was 100% successful with a mean of 1.37 attempts (95% confidence interval 0.58-2.16) and 180 s for placement (95% confidence interval 97.92-262.08). Five percent of LMGP had a complication vs. 0% for USG (p = 1.0).

Conclusions: USG improved first-pass and overall success of radial arterial line cannulation while reducing time to access and attempts when used by novice emergency medicine interns.

Keywords: arterial line; critical care; point-of-care ultrasound; resident education and training.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Catheterization, Peripheral*
  • Emergency Medicine*
  • Humans
  • Palpation
  • Prospective Studies
  • Ultrasonography, Interventional
  • Vascular Access Devices*