During thoracic outlet syndrome evaluation, which modality is used to monitor the limb?

• A. CW-Doppler
• B. PVR
• C. PPG
• D. Sphygmomanometer

Answer: (A)

In thoracic outlet syndrome evaluation, you need a method that shows arterial flow in real time as the arm is placed in provocative positions. Continuous-wave Doppler provides an ongoing signal of blood flow velocity in the subclavian/axillary arteries, so you can observe flow presence, reduction, or occlusion during maneuvers like abduction or external rotation. This immediate feedback directly demonstrates vascular compression when the limb is stressed.

Other options measure perfusion in different ways but don’t track arterial flow continuously in the large arm arteries during position changes. PVR and PPG assess volume changes or microvascular perfusion, not dynamic arterial patency, and a sphygmomanometer only gives static pressure without monitoring flow.