tension pneumothorax

-- a true surgical emergency (without waiting for x-ray confirmation)

-- mechanism: one-way valve → ↑ intrapleural pressure → lung collapse →
mediastinal shift → venous return ↓ → cardiac output ↓

-- S/S: hypotension associated with
absent breath sound, tracheal shift, jugular vein engorgement, hypoxia

-- needle thoracostomy:
2nd intercostal space at midclavicular line or
5th intercostal space at midaxillary line