Background: Even with ultrasound guidance, arterial cannulation in children can be challenging.
Objective: To compare the short-axis/out-of-plane (SAX) with the long-axis/in-plane (LAX) technique for ultrasound-guided arterial cannulation in children.
Design: A randomised controlled trial.
Setting: A tertiary university hospital, from 5 January 2015 to 21 April 2015.
Patients: 101 children, American Society of Anesthesiologists' physical status 1 or 2 and younger than 5 years of age.
Interventions: All were randomised into one of four groups according to age and ultrasound guidance technique: infants with SAX technique (n = 25), infants with LAX technique (n = 25), children with SAX technique (n = 25) and children with LAX technique (n = 26). Ultrasound-guided arterial cannulation was performed under general anaesthesia via the radial or posterior tibial artery, depending on individual position and operative field.
Main outcome measures: The primary outcome was the total time to successful cannulation. Secondary outcomes included diameter and depth of the artery, time variables (imaging time, time to first successful puncture and time between first successful puncture and cannulation), number of puncture attempts, success rates (first puncture and final cannulation), posterior wall puncture rate and complications.
Results: Ultrasound-guided arterial cannulation was successful in 97 children (96.0%). There were no significant differences in the total time to successful cannulation between the two groups. Ultrasound imaging time was significantly longer in the LAX group than in the SAX group (46.5 ± 39.2 vs 16.0 ± 17.6 s; 95% confidence interval of mean difference, -42.7 to -18.3; P = 0.000). However, the posterior wall puncture rate was significantly higher in the SAX group than in the LAX group (95.7% vs 18.0%; P = 0.000; odds ratio 0.01; 95% confidence interval, 0.002 to 0.048). There were no statistically significant differences in other secondary outcomes.
Conclusion: Despite the longer imaging time with the LAX approach, there was no significant difference in the total time to successful cannulation between the two techniques. The posterior wall puncture rate was lower in the LAX group than in the SAX group.
Trial registration: Clinicaltrials.gov (identifier: NCT02333786).