If a patient with a coronary artery bypass graft (CABG) has a chest tube, what might indicate an air leak in the collection unit?

The presence of bubbling in the water seal chamber of a chest tube collection unit is a significant indicator of an air leak. Normally, when a chest tube is functioning correctly and there is no air leak, the water seal chamber should remain relatively still without bubbling. However, if there is an air leak, you will observe consistent bubbling in this chamber.

This bubbling occurs because air is escaping from the pleural space through the chest tube and entering the water seal chamber, indicating that air is present in the thoracic cavity, which should not be the case in a normally functioning chest tube drainage system. Recognizing this sign is crucial as it necessitates further evaluation and possible intervention to address the leak in order to restore proper drainage and prevent complications associated with pneumothorax or inadequate lung expansion.

Other options do not indicate an air leak: no bubbling suggests a sealed system, increased drainage may indicate normal fluid output, and decreased drainage could signal other issues unrelated to air leaks.