Which priority action should a nurse take for a patient with a chest tube that has become disconnected?

When a chest tube becomes disconnected, the priority action is to reestablish the system by placing the end of the tube in sterile water. This action is critical because it helps to prevent air from entering the pleural space, which could lead to a tension pneumothorax or worsen any existing respiratory distress. By submerging the tube in sterile water, a water seal is created, allowing for the escape of air or fluid from the pleural cavity while preventing air from entering.

The other options, while they may seem relevant, could lead to complications. For example, clamping the chest tube can cause increased pressure in the pleural space and potentially lead to a collapsed lung. Although notifying the physician is important, it does not address the immediate need to manage the disconnection. Simply attaching a new drainage system does not quickly resolve the situation and could further increase risk during the transition.

Thus, placing the disconnected end of the chest tube in sterile water is the most effective immediate measure to ensure patient safety and maintain the integrity of the chest drainage system.