The aim of this study was to determine the degree of head rotation that creates the maximal anatomic separation between the right internal jugular vein and the carotid artery.
Design
Single-center prospective, observational cohort study.
Setting
University medical center.
Participants
Fifty patients aged>21 years and undergoing cardiac surgery.
Interventions
An ultrasound machine equipped with a digital caliper was used to determine the relational anatomy of the internal jugular vein and the carotid artery, with patients in the Trendelenburg position at head angles of –15°, 0°,+15°,+30°,+45°,+60°,+75°, and+90°.
Measurements and Main Results
When examining the percentage of the internal jugular vein vertical diameter that is not overlapped by the carotid artery (vertically unencumbered), there was a difference between the head angle groups (p<0.01). Unencumbered vertical distance was different between+75° versus 0°, and+75° versus+15°. At+75°, 60.3%±5.3% of the internal jugular vein was unencumbered vertically, whereas at 0°, it was 37.2%±3.9%, and at+15° it was 40.3%±3.8%. Only 72% of the patients were able to position their head at+75°, and 54% of the subjects were able to position their head at+90°.
Conclusion
The authors found the internal jugular vein becomes more vertically separated from the carotid artery at more extreme angles of contralateral head rotation.
