Background Arterial line cannulation in paediatric patients is traditionally performed by palpation or with Doppler auditory assistance in locating the artery before catheterization. It is not clear whether ultrasound guidance offers benefits over these methods. Objectives To assess first attempt success rates and complication rates when ultrasound guidance is used for arterial line placement in the paediatric population, as compared with traditional techniques (palpation, Doppler auditory assistance), at all potential sites for arterial cannulation (left or right radial, ulnar, brachial, femoral or dorsalis pedis artery). Search methods We searched CENTRAL, MEDLINE (Ovid) and Embase (Ovid). We also searched databases of ongoing trials (ClinicalTrials.gov (www.clinicaltrials.gov/), Current Controlled Trials metaRegister (www.controlled-trials.com/), the EU Clinical Trials register ( www.clinicaltrialsregister.eu/) and the WHO International Clinical Trials Registry Platform(http://apps.who.int/trialsearch/). We tried to identify other potentially eligible trials by searching the reference lists of retrieved included trials and related systematic or other reviews. We searched until January 2016. Selection criteria We included randomized controlled trials (RCTs) comparing ultrasound guidance versus palpation or Doppler auditory assistance to guide arterial line cannulation in paediatrics. Data collection and analysis Two review authors independently assessed the risk of bias of included trials and extracted data. We used standard Cochrane meta-analytical procedures, and we applied the GRADE method to assess the quality of evidence. Main results We included five RCTs reporting 444 arterial cannulations in paediatric participants. Four RCTs compared ultrasound with palpation, and one compared ultrasound with Doppler auditory assistance. Risk of bias varied across studies, with some studies lacking details of allocation concealment. It was not possible to blind practitioners in all of the included studies; this adds a performance bias that is inherent to the type of intervention studied in our review. Only two studies reported the rate of complications. Meta-analysis showed that ultrasound guidance produces superior success rates at first attempt (risk ratio (RR) 1.96, 95% confidence interval (CI) 1.34 to 2.85, 404 catheters, four RCTs, moderate-quality evidence) and fewer complications, such as haematoma formation (RR 0.20, 95% CI 0.07 to 0.60, 222 catheters, two RCTs, moderate-quality evidence). Our results suggest, but do not confirm, that a possible advantage of ultrasound guidance for the first attempt success rate over other techniques is more pronounced in infants and small children than in older children. Similarly, our results suggest, but do not confirm, the possibility of a positive influence of expertise in the use of ultrasound on the first attempt success rate. We also found improved success rates within two attempts (RR 1.78, 95% CI 1.25 to 2.51, 134 catheters, two RCTs, moderate-quality evidence) with ultrasound guidance compared with other types of guidance. No studies reported data about ischaemic damage. We rated the quality of evidence for all outcomes as moderate owing to imprecision due to wide confidence intervals, modest sample sizes and limited numbers of events. Authors' conclusions We identified moderate-quality evidence suggesting that ultrasound guidance for radial artery cannulation improves first and second attempt success rates and decreases the rate of complications as compared with palpation or Doppler auditory assistance. The improved success rate at the first attempt may be more pronounced in infants and small children, in whom arterial line cannulation is more challenging than in older children.
