Final answer:
Two chest tubes are needed for a bilateral pneumothorax, which involves the placement of one tube on each side of the chest to remove air from the chest cavity and allow the lungs to re-expand.
Step-by-step explanation:
For a bilateral pneumothorax, which is a medical condition where air escapes into the chest cavity on both sides of the chest and causes both lungs to collapse, two chest tubes are typically required. One tube is inserted into each side of the chest to reestablish the negative pressure paramount for lung inflation. These chest tubes are placed in the pleural space, usually in the anterior chest wall around the 4th or 5th intercostal space, and lateral to the pectoralis major muscle, under suction to effectively remove the air and allow the lungs to re-expand.