Importance of the Upper Extremity Position for a Safe and Effective Axillary Block: a Comparative Study

Our aim was to determine the ideal position of upper extremities during ultrasonography guidance for axillary block. The position that provides the shortest distance between the median and musculocutaneous nerves was assumed to be the most appropriate position for axillary block.

In this cross-sectional study, 120 (45 female and 75 male) patients were placed in a position with a shoulder at 90° / elbow 90° (position 1) and a shoulder 90° / elbow 0° (position 2). The intersection point of the biceps brachii muscle with the lower border of the pectoralis major muscle is defined as the proximal level (P). Distal level (D) is reffered as 5 cm below the proximal level. In the positions described above, the distance between median and musculocutaneous nerves was measured proximal (positions 1P and 2P) and distal levels (positions 1D and 2D). It was investigated whether these measurements differed between the groups and whether the body mass index or the gender.

The shortest mean distance (10.24±3.95 mm) between the two nerves was determined when the shoulder position 90°/elbow position 0° at the distal level (1D) and the longest mean distance (13.41±4.26 mm) was determined when shoulder position 90°/elbow position 90° at the proximal level (2P). In all four cases, there was no difference in the results between men and women. There was no relationship between the measurement results and the body mass indexes and age of the patients.

Appropriate positioning of the upper extremities is important for achieving optimal position during axillary block. Thereby, the procedure can be safely and effectively performed with lesser amounts of local anaesthetic solution and a decreased number of manoeuvres with needle during infiltration.