The Adson's test is done to assess compression of the subclavian artery.
The test is performed as follows:
1)Monitor the patient's radial pulse at the wrist while you abduct, extend, and externally rotate the upper extremity at the shoulder joint (keeping the elbow straight)
2)Have the patient take a deep breath, rotate, and extend their head TOWARD the side being tested
The test is positive if there is a marked decrease or absence of the radial pulse.

