Effects of different modes of ventilation and head position on the size of the vena jugularis interna.

PURPOSE Right internal jugular vein (RIJV) catheterisation is a common procedure in patients undergoing surgery. We aimed to compare diameters and the cross-sectional area (CSA) of the RIJV when the head is in a neutral or 30-degree rotated position during mechanical ventilation in various modes and spontaneous ventilation. METHODS Thirty patients undergoing surgery were included in the study. In each patient, still ultrasound images of the vena jugularis interna were taken with the head in a neutral position and with the neck rotated 30 degrees to the left, first under spontaneous ventilation (group S), then after the induction of anaesthesia under volume-controlled ventilation (group V) and under pressure-controlled ventilation (group P). The six still images were evaluated in terms of transverse and anteroposterior diameters and CSA. RESULTS Diameters in the neutral and lateral positions in group S were significantly smaller than in group P and group V (neutral transverse p = 0.01, anteroposterior p = 0.041, rotated transverse p = 0.01, anteroposterior p = 0.03). The CSAs of the RIJV in the neutral and lateral positions were significantly larger in group P and group V than Group S (lateral CSA p = 0.001, neutral CSA p = 0.002). CSA increased significantly only in group P when the head was rotated 30 degrees laterally (p = 0.002). CONCLUSION We conclude that both pressure-controlled and volume-controlled mechanical ventilation have similar effects on the CSA and diameters of the RIJV. Positioning of the head with a 30-degree rotation laterally has different effects on CSA depending on the ventilation mode used. A neutral position should be preferred with spontaneous ventilation whereas 30 degree rotation should be preferred in patients under pressure-controlled and volume-controlled ventilation.