This study was performed to ultrasonographically demonstrate the changes in relationship between the right internal jugular vein (IJV) and an anatomical landmark in two different head positions: neutral and rotational.

Background: This study was performed to ultrasonographically demonstrate the changes in relationship between the right IJV and an anatomical landmark in two different head positions: neutral and rotational.

Methods: One hundred patients scheduled for elective surgery under general anesthesia with endotracheal intubation were enrolled in this study. The patients were placed in the supine position with a neutral head position and without a pillow. The apex of the triangle formed by the sternal and clavicular heads of the sternocleidomastoid muscle and clavicle was marked (anatomical landmark point: AL point). The ultrasonography of the neck anatomy was performed, and a mark was placed at the central point of the IJV to the skin (ultrasonography point: US point). The other investigator measured the distances from the AL point to the US point (AL-US distance). The patient's head was then turned 30° to the left; the same procedure was repeated and the AL-US distance was again measured. The changes in AL-US distance were calculated.

Inclusion Criteria:

• 100 patients weighing 40 - 100 kg and with heights of 140 - 190 cm

Exclusion Criteria:

• a history of neck surgery or trauma involving the neck, previous IJV-related interventions (e.g., venous catheterization), limitation of neck movement, and a body mass index ≥ 30.

Patients scheduled for elective surgery under general anesthesia with endotracheal intubation, were enrolled in the study between May 2009 and February 2010.