Subclavian and axillary vessel anatomy: a prospective observational ultrasound study.

Purpose: The primary objective of this study was to define the ultrasound-derived anatomy of the axillary/subclavian vessels. As a secondary objective, we evaluated the relationship between the vascular anatomy and demographic, anthropometric, and hemodynamic data of patients.

Methods: This observational anatomical study used bedside ultrasound with 150 cardiac surgical patients in the operating room. Bilateral axillary and subclavian anatomy was determined using a high-frequency ultrasound probe with fixed reference points. Images were recorded and analyzed, and correlation with demographic, anthropometric, and hemodynamic data was performed.

Results: The images were adequate to evaluate potential anatomical variations in 97.4% of patients with a body mass index as high as 46.4 kg·m. The mean (standard deviation) diameter of the axillary vein was 1.2 (0.3) cm on the right side and 1.1 (0.2) cm on the left side. The dimensions of the axillary vein were larger on the right side in 69% of patients. The vein was located directly over the artery in the mid-clavicular view in 67% of the patients and in lateral-clavicular view in only 7% of the patients. As we moved the probe laterally, the vein was lateralized in relation to the artery in 89% of patients. There was no significant correlation between the hemodynamic data and vessel size, although direct correlation was found between body mass index and the depth of the vessel (P < 0.001). The axillary vein area was smaller in females than in males (P < 0.002), and in 4% of patients, the axillary vein was in an aberrant position.

Conclusions: In patients undergoing cardiac surgery, axillary vessel anatomy varied considerably, and the patients' hemodynamics could not predict the size of the axillary vessels. Only the patients' weight correlated moderately with the depth of the vein.