Which of the following is a late sign of tension pneumothorax?

• A. Chest pain
• B. Neck vein distention
• C. Cyanosis
• D. Unilateral absent breath sounds

Answer: (C)

Cyanosis is a late sign because it appears only after severe hypoxemia and decreased cardiac output have developed from the rapid pressure buildup in the chest. In tension pneumothorax, air trapped under pressure collapses the lung and shifts the mediastinum, which quickly compromises venous return to the heart. Early indicators reflect respiratory distress and impaired ventilation: tachypnea, tachycardia, chest pain, diminished breath sounds on the affected side, and neck vein distention from rising intrathoracic pressure. The body can compensate for a time, but as oxygen delivery falls and perfusion worsens, tissues desaturate, leading to cyanosis. Finding cyanosis indicates a progressed, life-threatening state requiring immediate intervention.