In the normal individual all peripheral pulses demonstrate a respiratory effect with systolic blood pressure falling 3 to 10 mm Hg in normal inspiration.1 As this pressure change is too small to be appreciated by clinical palpation, the discovery of an exaggerated respiratory effect, the paradoxical pulse, is always an important clinical observation. Such a finding immediately raises the question of restrictive cardiac or obstructive airway disease, conditions which exaggerate the normal and do not cause a "paradoxical" respiratory effect on pulse amplitude.2 However, when only the pulses of the upper extremity are involved, a regional rather than a central abnormality must be considered.
Little mention is made in the literature of the effect of respiration on the manifestation of the thoracic outlet syndromes. Held inspiration is an important aspect of the Adson maneuver for detecting neourovascular compression by a cervical rib or anterior scalene muscle.3 The
Swinton NW, Nelson WP, Hall RJ, Harrell JE. Paradoxical PulseA Manifestation of the Thoracic Outlet Syndromes. Arch Intern Med. 1969;124(4):492–494. doi:10.1001/archinte.1969.00300200104017