During the evaluation of a chest tube system, what indicates that the chest tube is not functioning effectively?

The indication that the chest tube is not functioning effectively is demonstrated by continuous bubbling in the water-seal chamber. A chest tube is designed to promote the evacuation of air or fluid from the pleural space, and the water-seal chamber should ideally maintain a level of water that allows for fluctuations in response to respiratory movements. Continuous bubbling in this chamber suggests a possible air leak in the system, indicating that air is entering the pleural space instead of being effectively drained. This leak could undermine the therapy's effectiveness and compromise lung expansion.

Fluctuation in the water-seal chamber is a normal finding that indicates the system is working properly, as it corresponds to intrathoracic pressure changes during breathing. Absence of bubbling in the suction chamber is a normal state if the suction is not being actively used or if the system is properly functioning without needing additional suction pressure. An increase in respiratory rate may not directly correlate with the effectiveness of the chest tube, as it can occur for a variety of reasons unrelated to tube function. Thus, option C is the most definitive indicator of improper function in this scenario.