<prompt> A 45-year-old smoker patient presents with sudden onset unrelenting chest pain with loss of peripheral pulses. Lung fields are clear and has normal air entry. First differential diagnosis is?Mirizzis syndromeAcute aoic syndromeAcute pericarditisSpontaneous pneumothorax  <response>: Acute Aoic Syndrome- Chest pain loss of peripheral pulses Mirizzis syndrome - Common hepatic duct obstruction caused by extrinsic compression from an impacted stone in cystic duct or infundibulum of gall bladdder. Acute pericarditis Diffuse chest pain at rest for hours - days Radiation to left shoulder Phrenic nerve involvement Relief: - on sitting Pericardial friction rub heard on auscultation Spontaneous pneumothorax Absent air entry. Hyper resonant lung. More blackening. Decreased breath sounds. 