title: Ultrasound-guided small vessel cannulation: long-axis approach is equivalent to short-axis in novice sonographers experienced with landmark-based cannulation.
abstract: BACKGROUND
  Our primary objective was to describe the time to vessel penetration and difficulty of long-axis and short-axis approaches for ultrasound-guided small vessel penetration in novice sonographers experienced with landmark-based small vessel penetration.
  
  
  METHODS
  This was a prospective, observational study of experienced certified emergency nurses attempting ultrasound-guided small vessel cannulation on a vascular access phantom. We conducted a standardized training, practice, and experiment session for each participant. Five long-axis and five short-axis approaches were attempted in alternating sequence. The primary outcome was time to vessel penetration. Secondary outcomes were number of skin penetrations and number of catheter redirections. We compared long-axis and short-axis approaches using multivariable regression adjusting for repeated measures, vessel depth, and vessel caliber.
  
  
  RESULTS
  Each of 10 novice sonographers made 10 attempts for a total of 100 attempts. Median time to vessel penetration in the long-axis and short-axis was 11 (95% confidence interval [CI] 7-12) and 10 (95% CI 6-13) seconds, respectively. Skin penetrations and catheter redirections were equivalent and near optimal between approaches. The median caliber of cannulated vessels in the long-axis and short-axis was 4.6 (95% CI 4.1-5.5) and 5.6 (95% CI 5.1-6.2) millimeters, respectively. Both axes had equal success rates of 100% for all 50 attempts. In multivariable regression analysis, long-axis attempts were 32% (95% CI 11%-48%; p=0.009) faster than short-axis attempts.
  
  
  CONCLUSIONS
  Novice sonographers, highly proficient with peripheral IV cannulation, can perform after instruction ultrasound-guided small vessel penetration successfully with similar time to vessel penetration in either the long-axis or short-axis approach on phantom models.
authors.affiliation: Oregon Health and Science University, Department of Emergency Medicine, Portland, Oregon.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Erickson
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado ; University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Liao
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado ; University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado ; Colorado School of Public Health, Department of Epidemiology, Aurora, Colorado.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Haukoos
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado ; University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado.
authors.forename: Erica
authors.initials: E
authors.lastname: Douglass
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado ; University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado.
authors.forename: Margaret
authors.initials: M
authors.lastname: DiGeronimo
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado.
authors.forename: Eric
authors.initials: E
authors.lastname: Christensen
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado.
authors.forename: Emily
authors.initials: E
authors.lastname: Hopkins
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado.
authors.forename: Brooke
authors.initials: B
authors.lastname: Bender
authors.affiliation: Denver Health Medical Center, Department of Emergency Medicine, Denver, Colorado ; University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado.
authors.forename: John L
authors.initials: JL
authors.lastname: Kendall
mesh_terms: D002406:Catheterization, Peripheral / Q000379:methods* / Q000451:nursing; D002408:Catheters, Indwelling; D002983:Clinical Competence; D004635:Emergency Medicine / Q000193:education*; D006801:Humans; D019300:Medical Errors / Q000517:prevention & control*; D019047:Phantoms, Imaging; D011446:Prospective Studies; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000451:nursing