Abstract
OBJECTIVE:To compare the area of the lumen of the axillary and subclavian veins using ultrasound (US) in 50 healthy volunteers.METHODS:Using an ultrasound device, depth, area, short axis vein length and long axis vein, vein-artery and vein-pleura distances were measured for axillary and subclavian approaches.RESULTS:The mean cross-sectional area of the axillary vein was greater than the mean cross-sectional area of the subclavian vein (327±89 mm2 versus 124±46 mm2, P<0.001). Both the mean transverse (10±2mm versus 9±2mm) and longitudinal axes (39±8mm versus 17±7mm) of the axillary vein were greater than those of subclavian vein (P<0.01, P<0.001, respectively). The depths of the axillary and subclavian veins were similar (21±6mm versus 20±6mm, P=0.43). The axillary and subclavian arteries were visualised in 3 and 45 volunteers, respectively (P<0.001). The pleura was seen in 25 and 37 volunteers with the axillary and subclavian approaches, respectively (P=0.01). The distance between the pleura and the subclavian vein was smaller (6±2mm versus 8±3mm, P<0.04).CONCLUSION:The present US study shows that visualisation of the axillary vein under US is greater than that for the subclavian vein, mainly due to a better alignment with the long axis of the axillary vein leading to a greater cross-sectional area of the axillary vein.TRIAL REGISTER NUMBER:NCT01647815.