What does lack of fluctuation (tidaling) in the water seal chamber of a chest tube indicate?

Lack of fluctuation, or tidaling, in the water seal chamber of a chest tube indicates that the lung has likely fully expanded. When a chest tube is in place, the water seal chamber should demonstrate fluctuations that correspond with the patient's breathing cycle. This fluctuation occurs as the lung expands and contracts, allowing the water seal to rise and fall with each breath.

If there is no movement in the water seal chamber, it suggests that there is no ongoing pleural pressure change, which typically occurs when the lung is properly inflated and adheres to the chest wall. This can also imply that the pleural space is no longer collecting fluid or air, signaling that the primary issue that led to the chest tube insertion may have been resolved. Therefore, lack of tidaling is often a positive indicator that the lung has re-expanded, and the monitoring of the water seal chamber can provide valuable information regarding the status of the lung and the effectiveness of the treatment administered.