What is the typical setting for an effective suction unit?

• A. 50 L/min and 500 mmHg
• B. 10 L/min and 50 mmHg
• C. 20 L/min and 100 mmHg
• D. 30 L/min and 300 mmHg

Answer: (D)

Effective airway suction relies on a balance between enough vacuum to pull secretions out and sufficient flow to clear the airway without causing tissue injury. For an adult patient, a typical, effective setting is about 300 mmHg of negative pressure with a flow around 30 L/min. This combination clears secretions efficiently while minimizing the risk of mucosal trauma or hypoxia. Settings with much lower vacuum may fail to remove thicker secretions, while much higher vacuum increases injury risk. Similarly, insufficient flow can make suction ineffective even if the pressure is adequate. So 30 L/min at 300 mmHg best matches standard practice.