Optimal head rotation for internal jugular vein cannulation when relying on external landmarks

External anatomic landmarks have traditionally been used to approximate the location of the neck blood vessels to optimize central venous cannulation of the internal jugular vein (IJV) while avoiding the common carotid artery (CCA). Head rotation affects vessel orientation, but most landmark techniques do not specify its optimal degree. We simulated catheter insertion via both an anterior and central approach to the right IJV using an ultrasound probe held in the manner of a syringe and needle in 49 volunteers. Increased head rotation from 0°, 15°, 30°, 45°, and 60° to the left of midline was associated with higher probability of a simulated needle contacting the IJV and the CCA. For both approaches, the risk of CCA contact was <10% for head rotations of ≤45°. Increased body surface area (BSA) and body mass index (BMI) were associated with more CCA contact at head rotations of 45° or 60°. To optimize IJV contact while reducing the likelihood of inadvertent contact with the CCA, the head should be rotated no more than 30° in patients with high BMI or BSA, but it may be turned to 60° if BMI or BSA is low.