The purpose of this study was to evaluate the effect of head rotation on the anatomical relationship of the right internal jugular vein (RIJV) and the carotid artery (CA) with using ultrasound images in Korean patients.

We investigated 117 patients (age range: 16-87 years old) who were placed in the supine position, but not in the Trendelenburg position. An ultrasound probe was placed on the right neck at the apex of the triangle formed by the head of the sternocleidomastoid muscle and the clavicle, and it was directed toward the ipsilateral nipple at a 30 degree angle to the coronal plane. For each head rotation (0, 30, 60 degrees), we measured the horizontal diameter of the RIJV and CA, and the percentage of overlap of the CA and the RIJV with using an ultrasound system.

The mean RIJV diameter was 18.4 ± 4.3 mm and the mean CA diameter was 7.5 ± 1.2 mm at the neutral head position. Following head rotation, the percentage overlap of the CA and RIJV increased significantly (0°: 32.7%, 30°: 45.4%, 60°: 57.0%) (P < 0.05). The percentage overlap of the CA and RIJV in the neutral head position increased more in the patients with a BMI over 25. However, age did not have any effect on the percentage of overlap.

Head rotation toward the contralateral side increases the percentage of overlap of the CA and RIJV. To decrease the risk of CA puncture, rotate the head from the neutral position as little as possible when performing RIJV catheterization.