Background: Radial artery catheterization (RAC) remains challenging, with a high failure rate. This study investigated whether ultrasound-measured radial artery (RA) diameter could predict RAC failure in patients undergoing major cardiac or vascular surgery. Methods: Consecutive patients scheduled for major cardiac or vascular surgery were prospectively included. Ultrasound images of the left RA were acquired by one operator, while a second operator, blinded to these images, performed RAC using the palpation method. RAC failure was defined as three or more attempts, a change in operator, or cannulation site. All ultrasound images were subsequently analyzed by an expert vascular physician, also blinded. RA internal diameter and depth were measured. Intra- and inter-observer reproducibility were assessed. Results: Of 247 patients, 58 (23%) experienced RAC failure. Absent or weak radial pulse (OR 6.36, 95% CI 2.59–15.65; p < 0.001), female sex (OR 2.55, 95% CI 1.36–4.77; p = 0.003), and wrist circumference <18 cm (OR 1.96, 95% CI 1.08–3.54; p = 0.03) each significantly increased RAC failure risk. The RA internal diameter was significantly smaller in the failure group (1.9 ± 0.4 vs 2.1 ± 0.4 mm, p < 0.01). RA was also deeper in the failure group (3.4 ± 1.6 vs 2.9 ± 1.1 mm, p = 0.05). The area under the curve for RA internal diameter to predict RAC failure was 0.62 (95% CI 0.53–0.70, p = 0.007), with an optimal threshold of 1.8 mm. RAC failure prolonged anesthesia induction and doubled the risk of hematoma ( p < 0.001). Intra- and inter-observer agreement for RA internal diameter were excellent (ICC 0.86, 95% CI 0.78–0.92 and 0.94, 95% CI 0.91–0.97, respectively). Conclusion: A small RA internal diameter significantly increases RAC failure risk. These findings should inform cannulation site selection, technique, and operator choice to improve procedural success and patient safety.
Paniego et al. (Tue,) studied this question.