Effects of prolonged head-down tilt on internal jugular vein cross-sectional area.

BACKGROUND: Head-down tilt is often used to assist cannulation of the internal jugular vein (IJV). However, the optimal duration of tilt before cannulation is not well defined.

METHODS: Fifteen healthy volunteers were studied by B-mode duplex sonography to assess changes in cross-sectional area (CSA) of the right IJV during 10 degrees head-down tilt.

RESULTS: Median CSA in the supine position was 102 mm(2) [range 16-266, mean (SD) 113 (69)]. CSA increased to 139 mm(2) [23-388, 158 (93)] immediately after tilting (P<0.0001, repeated measures ANOVA). No significant further change was noted in the next 20 min. CSA returned to baseline level after return to the supine position.

CONCLUSION: The 10 degrees head-down tilt manoeuvre in healthy volunteers causes an immediate, significant increase in CSA in the right IJV. A longer tilt did not cause further increase in jugular CSA.