Ultrasound evaluation of the radial artery for arterial catheterization in healthy anesthetized patients.

The purpose of this study was to assess the anatomy of the radial artery using ultrasound in anesthetized patients, and to correlate its anatomical data with patients' characteristics. The success rate of radial artery cannulation using ultrasound was also evaluated to analyze the relationship between the anatomical data and the success rate. Study 1 One hundred ninety-five patients scheduled for general anesthesia were enrolled. Ultrasound measurements were obtained when the vital signs were stable after anesthesia induction. The wrist joint of patients were extended to 30°. The diameter and depth of the radial artery, and the angle between the radial artery and skin surface were measured using ultrasound. Anatomical data were correlated with patients' characteristics. Study 2 Arterial cannulation was performed in 125 patients using long-axis in-plane technique to evaluate the success rate using ultrasound. Study 1 The diameter of the radial artery was mean value of 2.2 ± 0.4 mm and larger than 0.9 mm in all patients. It had significant correlation with body surface area (BSA) (Pearson correlation 0.292, P < 0.001). The incidence of abnormal angle between the radial artery and skin surface was significantly higher in elderly patients (≥65 years) than young patients (P = 0.017). Study 2 The first attempt success rate of arterial catheterization using ultrasound was 92.5 % using long-axis in-plane technique, regardless of patient's characteristics. For small sized adult patients, a 22G angio-catheter should be used during radial artery cannulation, because the radial artery diameter significantly correlated with BSA in healthy anesthetized patients. In addition, ultrasound-guided catheterization is recommended in elderly patients because the incidence of abnormal angle between the radial artery and skin surface was high.