Application of point-of-care ultrasound-guided tip navigation combined with visualised directional high-frequency linear array probe compression to improve the success rate of umbilical venous catheterisation in critical neonates: protocol of a multicentre randomised controlled trial in neonatal units.

Background: Conventional umbilical venous catheterisation (UVC) relies on 'blind' insertion without ultrasound guidance, resulting in low success and high complication rates. While point-of-care ultrasound (POCUS)-based tip navigation and location has improved this scenario by enabling real-time visualisation of the catheter tip during UVC, challenges remain when the catheter is inadvertently inserted into an incorrect vessel. Selecting effective intervention methods to correct the catheter direction has become a key research focus. This study aims to evaluate the safety and efficacy of a novel technique combining POCUS-guided tip navigation with visualised directional high-frequency linear array probe compression (P-TN+vdHLAP C). This technique is expected to become a standardised protocol for POCUS-guided UVC, improving catheterisation success rates, minimising the frequency of insertion attempts and reducing catheterisation time.

Methods: This prospective, multicentre, single-blind, superiority, 1:1 parallel, randomised controlled trial will recruit 100 infants who have failed the initial UVC attempt using the conventional method. Participants will be randomly assigned to either the intervention group receiving P-TN+vdHLAP C or the control group receiving POCUS-guided tip location. The primary outcome measure is the success rate of UVC, defined as the proportion of catheter placements that are successfully positioned at the entrance of the inferior vena cava into the right atrium, as confirmed by POCUS. Secondary outcomes include UVC procedure time, total number of catheter insertions and postoperative monitoring indicators such as catheter tip location, incidence of complications and umbilical catheter indwelling time. Outcome measures will be assessed at seven time points: immediately after catheter placement, 12 hours, 24 hours, 48 hours and 7 days postplacement, catheter removal and discharge. Data analysis will be conducted using R (V.4.3.2). Background: The study protocol has been approved by the ethics committee of Fujian Children's Hospital (protocol number 2024ETKLRK09019). Prior to enrolment, written informed consent will be obtained from the legal guardians of all participants by the study staff. On completion of the trial, the results will be submitted for peer-reviewed publication in an international scientific journal. Background: ChiCTR2400090737.