Does the resistive index of the radial artery change after arterial cannulation in patients undergoing abdominal surgery? A prospective observational study.

Background and Aims: To evaluate the flow at the cannulation site in the radial artery, the resistive indices (RIs) before cannula insertion and 6 h after decannulation were measured (primary outcome). The secondary outcomes were measurement of the artery size by anteroposterior (AP) diameter at the insertion site, RI and AP diameter at a point 4 cm proximal and in the ipsilateral ulnar artery before insertion and 6 h after cannula removal. Methods: In 96 patients requiring an arterial line during surgery, peak systolic velocity (PSV) and end-diastolic velocity (EDV) were measured to derive RI using a linear ultrasound transducer. The RI was measured at R1 (insertion point), R2, 4 cm proximal to R1, and U1 on the ipsilateral ulnar artery. The AP diameter of the arteries at baseline R1 Results: RI or AP diameter in R1 or R2 did not differ pre- and post-cannulation. Mean R1 Conclusion: The flow in the radial artery did not change following cannulation. The PSV and AP diameter in the ulnar artery increased after decannulation, suggesting a compensatory increase in flow.