title: A comparison of longitudinal and transverse approaches to ultrasound-guided axillary vein cannulation.
abstract: OBJECTIVE
  The axillary vein is an easily accessible vessel that can be used for ultrasound-guided central vascular access and offers an alternative to the internal jugular and subclavian veins. The objective of this study was to identify which transducer orientation, longitudinal or transverse, is better for imaging the axillary vein with ultrasound.
  
  
  METHODS
  Emergency medicine physicians at an inner-city academic medical center were asked to cannulate the axillary vein in a torso phantom model. They were randomized to start with either the longitudinal or transverse approach and completed both sequentially. Participants answered questionnaires before and after the cannulation attempts. Measurements were taken regarding time to completion, success, skin punctures, needle redirections, and complications.
  
  
  RESULTS
  Fifty-seven operators with a median experience of 85 ultrasound procedures (interquartile range, 26-120) participated. The frequency of first-attempt success was 39 (0.69) of 57 for the longitudinal method and 21 (0.37) of 57 for the transverse method (difference, 0.32; 95% confidence interval [CI], 0.12-0.51 [P = .001]); this difference was similar regardless of operator experience. The longitudinal method was associated with fewer redirections (difference, 1.8; 95% CI, 0.8-2.7 [P = .0002]) and skin punctures (difference, 0.3; 95% CI, -2 to +0.7 [P = .07]). Arterial puncture occurred in 2 of 57 longitudinal and 7 of 57 transverse attempts; no pleural punctures occurred. For successful attempts, the time spent was 24 seconds less for the longitudinal method (95% CI, 3-45 [P = .02]).
  
  
  CONCLUSIONS
  The longitudinal method of visualizing the axillary vein during ultrasound-guided venous access is associated with greater first-attempt success, fewer needle redirections, and a trend of fewer arterial punctures compared with the transverse orientation.
authors.affiliation: Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. ssommerkamp@gmail.com
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Sommerkamp
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Romaniuk
authors.forename: Michael D
authors.initials: MD
authors.lastname: Witting
authors.forename: Deanna R
authors.initials: DR
authors.lastname: Ford
authors.forename: Michael G
authors.initials: MG
authors.lastname: Allison
authors.forename: Brian D
authors.initials: BD
authors.lastname: Euerle
mesh_terms: D001291:Attitude of Health Personnel; D001367:Axillary Vein / Q000000981:diagnostic imaging*; D002405:Catheterization, Central Venous / Q000379:methods*; D002983:Clinical Competence; D018592:Cross-Over Studies; D004635:Emergency Medicine; D006801:Humans; D008953:Models, Anatomic; D010820:Physicians; D011795:Surveys and Questionnaires; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000379:methods*