Tension pneumothorax is associated with -

In tension pneumothorax the pressure in pleural space is positive throughout the respiratory cycle. This condition usually occurs during mechanical ventilation and resuscitative effos. Difficulty in ventilation during resuscitation or high peak inspiratory pressures during mechanical ventilation strongly suggest the diagnosis. Physical examination shows : Enlarged hemithorax Absent breath sounds Hyperresonance on percussion Shift of mediastinum to contralateral side The positive pleural pressure in tension pneumothorax is life threatening because ventilation is severely compromised and the positive pressure is transmitted to mediastinum resulting in decreased venous return to hea and reduced cardiac output. Hence it should be treated as a medical emergency. If not treated immediately the patient may die of inadequate cardiac output and hypoxemia. Ref Davidson edition23rd pg 627