What is the purpose of the suction-control chamber in a three-chamber chest drainage system?

• A. To regulate the amount of suction transmitted to the chest.
• B. To store drainage fluid.
• C. To seal the system from ambient air.
• D. To measure patient respiratory rate.

Answer: (A)

Regulating suction delivered to the chest is the primary job of the suction-control chamber. It uses a column of sterile water as a valve to set the maximum negative pressure that can be transmitted to the pleural space. When suction pulls on the system, air bubbles through the water, and the depth of that water column fixes the level of suction. This keeps the negative pressure within a safe, steady range, protecting tissues from injury and ensuring consistent drainage even if the suction source or patient pressure fluctuates.

Other parts of the system have different roles: the collection chamber stores the drained fluid, and the water-seal chamber provides a one-way barrier against ambient air while allowing air from the chest to escape. Measuring respiratory rate is not a function of this suction-control chamber.