In a chest tube drainage system, where is gentle, continuous bubbling considered normal?

• A. Water-seal chamber
• B. Suction control chamber
• C. Collection chamber
• D. Air leak monitor

Answer: (B)

Gentle, continuous bubbling is normal in the suction control chamber because this part of the chest tube system is designed to regulate and transmit the suction to the pleural space. The suction control chamber sits between the wall suction and the patient, with a column of water that creates resistance. As the wall suction draws air through, bubbles form in this water, and that bubbling signifies that negative pressure is being delivered to the chest. If suction is functioning, you’ll typically see steady, gentle bubbles; if there’s no bubbling, suction may not be reaching the system due to a kink, occlusion, or a disconnect. If the bubbling is excessive, the suction may be too strong or there could be an upstream obstruction. In contrast, the water-seal chamber is where tidaling with respiration is expected; continuous bubbling there usually indicates an air leak, not normal. The collection chamber collects drainage and should not routinely bubble. The air leak monitor helps detect leaks, but the normal, expected bubbling you look for with active suction is in the suction control chamber.