Intermittent bubbling in the water seal chamber usually indicates?

• A. Air leak.
• B. Pneumothorax.
• C. Obstruction.
• D. Dislodged chest tube.

Answer: (B)

Air movement through the chest-tube water-seal chamber reflects air escaping from the pleural space during breathing. When a pneumothorax is present, air from the lung enters the pleural space and is vented out through the chest tube into the water seal. This venting often occurs during exhalation or coughing, so you see bubbles that come and go with respiration. That intermittent bubbling indicates that air is intermittently entering and leaving the pleural space, which is typical of a pneumothorax that still has air to evacuate.

In contrast, continuous bubbling would suggest a constant air leak somewhere in the tubing, while no bubbling could point to obstruction or no air movement. If the chest tube were dislodged, you’d expect a loss of function in the drainage system rather than a pattern of intermittent bubbling.