 Normally, the parietal and visceral pleura are closely adhered together. In a pneumothorax, there is a puncture of visceral pleura, and now air rushes out into the pleural cavity. In a tension pneumothorax, there is a one-way valve where the air keeps accumulating in this space. You will compress the heart to the opposite side. This is a tension pneumothorax. To treat this emergently, we release the air by a needle third costumey. We choose a 14 or 16 gauge IV catheter. Feel for the second intercostal space in the mid-clavicular line on the affected side. We insert the needle, that should release a gush of air. Once the patient's blood pressure has stabilized, we also insert a chest tube.