Improving the “global use” of ultrasound for central venous access: a new supraclavicular scan by microconvex probe

Abstract

Introduction: Ultrasound (US) is increasingly used as a “global” tool to assist all the steps of a central venous catheter (CVC) insertion: choice of vein, venepuncture, prevention of malpositions, tip location, detection of complications. Methods: In this pilot study, we tested the use of the microconvex probe (MCP) as one multi-purpose US probe for CVC placement. In the first part of this study, the MCP was tested on 10 patients in order to define its accuracy (1) in identifying nerve-vascular bundles, (2) in visualizing the brachiocephalic-caval venous axis via the right supra-clavicular approach, (3) in detecting the pleural ‘sliding sign’ (which rules out pneumothorax). In all patients, all three goals were achieved. In the second part of this study, we performed 6 CVC placements, to test the possibility of adopting the MCP for (a) systematic scan of central veins (RaCeVA protocol), (b) puncture and cannulation of central veins (3 internal jugular veins and 3 axillary veins), (c) visualization of catheter/guidewire within the great vessels (via the right supraclavicular scan) so to locate the tip in the lower portion of the superior vena cava (SVC), (d) detection of pleural complications. Results: The MCP was effective for all of these purposes, with some concerns only with tip location: while the metal guidewire was visible within the SVC in all 6 patients, its tip was recognizable below the crossing between SVC and right pulmonary artery in only 2 cases, and the catheter was never recognizable within the great vessels, maybe because of its low echogenicity as compared to the metal guidewire. Discussion and Conclusions: Our pilot study suggests that the MCP may be used in all steps of CVC insertion. The supra-clavicular scan is a promising view for visualization of the guidewire within the great vessels deep into the SVC, though its effectiveness for tip location is still uncertain.