What is the first action to take if the water seal on a chest tube breaks?

When the water seal on a chest tube breaks, clamping the tube first is essential to prevent air from entering the pleural space. This action helps to maintain the negative pressure that is critical for lung re-expansion and prevents the risk of a pneumothorax, which can occur if air enters the pleural cavity during a malfunction of the chest tube system.

After clamping the tube, the next steps would involve covering the chest tube insertion site with a sterile dressing to create an airtight seal and then ensuring that the tube is replaced or fixed as soon as possible to restore the water seal function. Promptly calling for help can also follow these initial actions to ensure proper intervention. However, the immediate priority is to protect the patient from further complications by clamping the tube first.