Which action should you take to confirm the suction system is correctly set after adjusting?

• A. Refill underwater seal with saline
• B. Ensure the bellow is at the delta mark
• C. Cap the chest tube
• D. Increase the collection drainage

Answer: (B)

Verifying the suction level is done by checking the suction control chamber's indicator—the bellows—and making sure it sits at the delta mark. That delta line shows the target negative pressure; when the bellows reach it, you can be confident the suction is set correctly. If the bellows aren’t on the delta mark, adjust the suction regulator or wall suction until they are. This step directly confirms the system is delivering the intended suction. Other actions don’t verify suction: refilling the underwater seal with saline relates to maintaining the seal fluid, not confirming suction; capping the chest tube blocks drainage and can cause harm; and increasing the collection drainage changes output, not the suction setting.