Which chamber in a closed chest drainage system is used to regulate suction and may show bubbling?

• A. Water seal chamber
• B. Drainage reservoir
• C. Suction control chamber
• D. Collection chamber

Answer: (C)

The suction control chamber is responsible for setting and regulating the negative pressure applied to the chest. It uses a column of water to create a controlled suction level: as the wall suction draws air through, bubbles rise in this water column, and those bubbles show that suction is being transmitted to the system at the prescribed level. If the bubbling in this chamber is absent or inconsistent, the suction may not be properly delivered, and connections or the water level should be checked.

The water seal chamber, by contrast, acts as a one-way valve to prevent air from flowing back into the chest; it can bubble when there’s an air leak or during respiration, but it does not regulate suction. The drainage or collection chamber simply collects pleural fluid and does not control suction.