title: Anatomical variations of the internal jugular vein: implications for successful cannulation and risk of carotid artery puncture.
abstract: BACKGROUND
  Complications occur in over 15% of central venous cannulations, often a result of anatomical variations. This study aimed to determine the anatomical variations of the internal jugular vein (IJV), demonstrate the likely success of cannulation and assess the risk of carotid artery (CA) injury when catheterising the IJV using the external landmarks technique at various degrees of head rotation in the local population.
  
  
  METHODS
  100 elective cardiac surgical patients were prospectively enrolled. Simulated catheterisations were performed with patients placed in the Trendelenburg position. The standard landmark technique was used to identify anatomy. Simulations were done at six different degrees of rotation of the head: 0°, 30° and 60° for both right and left IJVs. Difficult catheterisation was defined as an IJV diameter < 7 mm.
  
  
  RESULTS
  There was no thrombosed or absent IJV in any patient. Catheterisation was potentially difficult in 15% of patients at 30° head rotation and more difficult for the left IJV than the right (20% vs. 10%; p < 0.05). The simulated needle hit the IJV in 82% of the attempts, but the needle was in the middle 80% of the vein only 70% of the time. Neck rotation increased the degree of overlap of the CA relative to the IJV from 20%-30% to 50%.
  
  
  CONCLUSIONS
  Anatomical variations play a significant role in determining the success of IJV catheterisation as well as the incidence of catheterisation-associated complications. This study emphasises the importance of using ultrasonography to guide IJV catheterisation, even in patients with seemingly normal neck anatomy.
authors.affiliation: Department of Anaesthesia, National University Hospital, 5 Lower Kent Ridge Road, Singapore.
authors.forename: Thanaporn
authors.initials: T
authors.lastname: Lorchirachoonkul
authors.forename: Lian Kah
authors.initials: LK
authors.lastname: Ti
authors.forename: Shivani
authors.initials: S
authors.lastname: Manohara
authors.forename: Soh Teng
authors.initials: ST
authors.lastname: Lye
authors.forename: Sue-Anne
authors.initials: SA
authors.lastname: Tan
authors.forename: Liang
authors.initials: L
authors.lastname: Shen
authors.forename: Dave Song Chua
authors.initials: DS
authors.lastname: Kang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020212:Carotid Artery Injuries / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D002405:Catheterization, Central Venous / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007601:Jugular Veins / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D011187:Posture; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult