Final answer:
The absence of fluctuation in the water seal chamber of a closed chest drainage system is an indication of lung re-expansion, as it suggests the air leak has resolved and the lung is no longer pulling air.
Step-by-step explanation:
A nurse caring for a client with pneumothorax who is attached to a closed chest drainage system needs to monitor for signs of lung re-expansion to ensure proper healing. Regarding the options provided, an absence of fluctuation in the water seal chamber of a drainage system can suggest that the lungs have re-expanded and no longer pull air in and out with breathing, indicating that the air leak has sealed and the lung has re-expanded. Continuous bubbling would suggest an ongoing air leak, decreased drainage could simply mean less fluid production, and increased chest pain is not a reliable indicator of lung re-expansion. Suction applied to the chest cavity in such medical situations helps to reestablish negative pressure and inflate the lungs.