How is suction engagement verified on a closed chest drainage system?

• A. The bellow is engaged to the delta mark in the E chamber
• B. The suction control chamber shows bubbling in the expected pattern
• C. The water-seal level remains constant
• D. The collection chamber is empty

Answer: (A)

Suction engagement is verified by checking the suction control chamber’s indicator: the bellows should be aligned with the delta mark. This delta mark is the calibration that tells you the system is delivering the prescribed negative pressure to the chest. When the bellows sits at that mark, the suction pathway is sealed and actively pulling air, which means suction is engaged.

Bubbling in the suction control chamber can occur for various reasons and doesn’t reliably confirm the exact level of suction being applied, so it isn’t a dependable indicator on its own. The water-seal level and the amount of drainage in the collection chamber don’t directly reflect whether suction is active; the seal level can be influenced by breathing effort and leaks, and drainage quantity varies with the patient and injury.