Percutaneous Cannulation of the Axillary Artery: Does the Position of the Brachial Plexus Correlate With Bony Landmarks That Could Be Used to Reduce the Risk of Complications?

Introduction Endovascular surgery is an innovative way of carrying out procedures such as transcatheter aortic valve insertion where the femoral artery is commonly used as an access point. Conditions like peripheral arterial disease can make endovascular procedures challenging when atherosclerotic plaques compromise the integrity of lower limb vessels. An alternative access point for these patients is required. Access through the axillary artery has been proposed; however, the close proximity of the brachial plexus introduces a risk of neural complications. This study aims to find an anatomical or bony landmark(s) to help identify an area of safety on the axillary artery that can be used to gain access. Materials and methods Nine cadavers were used in the study and five parameters were measured using the acromion and coracoid processes as bony landmarks. The 1st parameter measured the distance between the acromion and the coracoid process. The 2nd parameter was the diameter of the axillary artery taken at a plane extending from the acromion to the coracoid process - now defined as the coracoacromial plane. The 3rd measurement was the distance between the coracoid process and the midpoint of the axillary artery diameter taken at the above plane; it is proposed this will form a safe point on the axillary artery. The 4th parameter measured was the distance between the safe point on the axillary artery and the median nerve. The 5th parameter was the distance between the safe point and the thoracoacromial trunk. Measurements were taken using digital callipers and were recorded for both sides of the cadaver except for one. Using the data from the measurements, an area of safety was calculated and statistical analysis was carried out using Student's t-test and Pearson's correlation to look for significant differences between the left and right sides. Results The mean distance from the safe point of the axillary artery to the median nerve was 23.25 mm on the left and 27.10 mm on the right. The p-value was 0.7, which indicated no significant differences between both sides. The mean distance between the safe point and the thoracoacromial trunk was 11.31 mm on the left and 13.21 mm on the right. The p-value was 0.24, indicating no significant differences between both sides. The mean area of safety was larger on the right side with an area of 184.37 mm and smaller on the left side with an area of 158.93 mm. The p-value was 0.62, which indicated no significant differences between both sides. There was no clear relationship between the distance from the acromion to the coracoid process compared to the distance between the acromion and a defined safe point on the axillary artery. This was confirmed using a Pearson's correlation test, which resulted in a p-value of 0.53 on the left and 0.93 on the right. These values were above the critical value, suggesting no correlation. Conclusion The acromion and the coracoid process are important bony landmarks that can be used to define the coracoacromial plane that traverses the axillary artery whereby avoiding the cords of the brachial plexus, the median nerve as well as the thoracoacromial trunk. Implementing this approach to define a safe vascular access point on the axillary artery could minimise complications like brachial plexus injuries. Further studies on a larger sample size using radiological methods may need to be carried out to help increase confidence in these preliminary cadaveric findings.