Ultrasound-guided vs. palpation-guided techniques for radial artery catherisation in infants


  • Randomised controlled trial
  • 74 infants under 12 months of age, undergoing elective cardiac surgery allocated to either ultrasound-guided using short-axis view group (group US) or palpation-guided group (group P) (each n=37) for radial artery catherisation
  • Procedure performed by one of two anaesthetists (each had more than 2 years of experience in paediatric cardiac anaesthesia and done at least 50 cases US-guided radial arterial catherisation in paediatric patients prior to the study)
  • In both groups each patient had an US examination of their radial artery at proposed puncture site in short-axis (out-of-plane) view & video-recorded for analysis of arterial characteristics prior to insertion attempt.
  • In both groups, either an anterior puncture technique or posterior puncture (transfixion) technique were used.
  • Where catherisation failed within 10 mins of starting the procedure, study protocol was discontinued and total procedural time was recorded as 600 secs


  • Primary end point was first-pass success: higher in group US (68%) vs group P (38%) P=0.019
  • Number of attempts until successful catherisation: less attempts in group US (median 1 [IQR 1-2]) than in group P (median 2 [IQR 1-4]) P=0.023
  • Median procedural time until successful catherisation: no significant difference in between 2 groups – group US 102 secs [IQR 49-394], group P 218 secs [73-600] P=0.054
  • In group US of the 12 patients that had a failed 1st pass attempt, the patients tended to be younger (median 0 months [IQR 0-1]) and smaller (median 3.5kg [IQR 3.0-4.4])
  • Posterior puncture technique was used more by the operators (86% vs 14%) but the puncture technique rates were comparable in the 2 groups (group US 89% vs group P 84% P=0.74)

Take Home Message

  • In an experienced operators hands, use of ultrasound increased the first pass success rate for arterial line insertion and decreased the number of attempts until successful insertion compared to a palpation technique in infants less than 12 months.
  • These findings are similar to previous studies with older children as subjects.
  • Smaller and younger infants tend to be more difficult to put arterial lines in.

Reviewed by: Dr Pip Lane