A standardized “four-zone” ultrasound algorithm for post-insertion assessment of subclavian centrally inserted central catheters: a prospective agreement study of 868 vascular access patients

Routine post-insertion chest radiography (CXR) to confirm central venous catheter position is limited by its retrospective nature, radiation exposure, and procedural delays. This study evaluated the feasibility, safety, and efficiency of a standardized multimodal intra-procedural ultrasound protocol as an alternative to routine radiography in patients requiring subclavian centrally inserted central catheter (CICC) placement. This single-centre, prospective, observational agreement study included 868 adult patients undergoing placement of a CICC in a subclavian vein. A standardized intra-procedural ultrasound protocol integrating vascular tip navigation, the rapid atrial swirl sign (RASS) for tip location, and lung sliding assessment was performed. Routine post-insertion CXR served as the institutional reference comparator. The primary outcome was agreement between ultrasound and CXR on the final post-correction catheter status. Secondary outcomes included the final residual malposition rate, pneumothorax detection, turnaround time, cost-effectiveness, and environmental impact. Intra-procedural ultrasound identified initial catheter malposition in 51 cases (5.9%), all of which were corrected in real time. Ultrasound and CXR agreed on the final post-correction catheter status in 865 of 868 patients (99.65%; exact 95% confidence interval [CI] 98.99–99.93), and the final CXR-confirmed residual malposition rate was 0.12% (1/868; 95% CI 0.003–0.64). All three discordant cases were ultrasound-negative/CXR-positive. Exploratory operational screening indices for the initial ultrasound assessment were a sensitivity of 98.0% and a specificity of 99.9%. While ultrasound missed two cases of asymptomatic minimal pneumothorax (< 10%), neither required intervention. Implementation of the ultrasound protocol eliminated the 45-minute average wait time associated with radiography ( p < 0.001), avoided approximately 694.4 kg carbon dioxide equivalent emissions, and yielded net cost savings of CNY 97,180, with a benefit-cost ratio of 2.12. In this large prospective agreement study, a standardized four-zone intra-procedural ultrasound protocol showed near-complete agreement with routine CXR for final post-insertion assessment after subclavian CICC placement and, through real-time correction, reduced the residual malposition rate to 0.12%. These findings support an individualized, risk-stratified strategy in which routine post-insertion CXR may be waived in low-risk patients with normal ultrasound findings, rather than universal replacement of CXR. Multicentre external validation and formal diagnostic accuracy studies are warranted.