What does the suction control in a chest drainage system regulate?

• A. The amount of suction delivered to the patient based on the amount of water.
• B. The rate of drainage collection.
• C. The height of the water seal.
• D. The air flow in ambient chest.

Answer: (A)

Suction control sets how much negative pressure is delivered to the pleural space, using a water column to regulate it. The height of the water in the suction control chamber determines the amount of suction transmitted to the chest—more water means more suction (within the device’s safe range), and less water means less suction. This keeps the suction at a prescribed level to promote drainage without causing tissue injury. It’s not about the rate of drainage itself, nor does it regulate the water seal height in the other chamber or ambient air flow.