一位 55 歲高血壓病史病人主訴突發性劇烈「撕裂感」胸痛並輻射至背部。下列何項評估發現需護理師立即處理？

病人主訴突發性撕裂感胸痛輻射至背部，是主動脈剝離（Aortic Dissection）的典型表現。主動脈剝離會導致血管壁分層，進而阻塞分支血管的血流。足背脈搏消失（Absent pedal pulses）顯示下肢出現急性血管灌流不足，這是危及肢體存活與顯示剝離範圍擴大的緊急徵象，屬於「生理適應」中危及器官灌流的優先級別，必須立即通知醫師準備緊急外科介入。

The client's complaint of sudden, severe "tearing" chest pain radiating to the back is a classic presentation of aortic dissection. Aortic dissection causes splitting of the vessel wall, which can occlude blood flow to branching arteries. Absent pedal pulses indicate acute lower-extremity vascular hypoperfusion, an urgent sign that threatens limb viability and signals expansion of the dissection; under "physiologic adaptation," this falls into the highest-priority category of impaired end-organ perfusion and requires immediate notification of the physician in preparation for emergency surgical intervention.