title: Modified short-axis out-of-plane ultrasound versus conventional long-axis in-plane ultrasound to guide radial artery cannulation: a randomized controlled trial.
abstract: BACKGROUND
  Currently, short-axis out-of-plane (SA-OOP) and long-axis in-plane (LA-IP) ultrasound techniques are used to guide radial artery cannulation. In this study, we compared the success rate of a modified SA-OOP technique with that of traditional LA-IP.
  
  
  METHODS
  One hundred sixty-four patients who were to undergo liver surgery or splenic resection under general anesthesia were included. Using a sealed envelope method, patients were randomly divided into 2 groups: the modified SA-OOP or the LA-IP ultrasound guidance approaches. The number of cannula insertion attempts until success was recorded in both groups. The primary end point to compare the groups was the rate of cannula insertion successes on the first attempt. The secondary end points were also recorded and compared: insertion failure rate, inner diameter of the radial artery, depth of artery from the skin, ultrasonic location time, cannulation time, and vascular complications including thrombosis, hematoma, edema, and vasospasm.
  
  
  RESULTS
  The cannula insertion success rate on the first attempt was significantly higher in the modified SA-OOP group compared with the LA-IP group (proportion difference 15.7%, 95% confidence interval [CI], 0.6%-30.7%, P = 0.0158). However, the insertion failure rate was not different between groups (95% CI, -17.7% to 12.8%, P = 0.4969). The ultrasonic location time was significantly decreased in the modified SA-OOP group compared with the LA-IP group (mean difference -9.5 seconds, 95% CI, -10.6 to -8.5 seconds, P < 0.0001). However, there was no significant difference between groups for cannulation time (95% CI, -0.6 to 7.6 seconds, P = 0.1152), depth of artery (95% CI, -0.07 to 0.57 mm, P = 0.1050), and the diameter of the radial artery (95% CI, -0.30 to 0.03 mm, P = 0.1153).
  
  
  CONCLUSIONS
  The modified SA-OOP technique may improve the success rate of cannula insertion into the radial artery on the first attempt.
authors.affiliation: From the Department of Anesthesiology, Beijing YouAn Hospital, and Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China.
authors.forename: ZheFeng
authors.initials: Z
authors.lastname: Quan
authors.forename: Ming
authors.initials: M
authors.lastname: Tian
authors.forename: Ping
authors.initials: P
authors.lastname: Chi
authors.forename: YingHao
authors.initials: Y
authors.lastname: Cao
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: KeJun
authors.initials: K
authors.lastname: Peng
mesh_terms: D000328:Adult; D000368:Aged; D002406:Catheterization, Peripheral / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017534:Radial Artery / Q000000981:diagnostic imaging*; D018084:Ultrasonography, Interventional / Q000379:methods*