When testing a mechanical suctioning unit, you should turn on the device, clamp the tubing, and ensure that it generates a vacuum pressure of more than:

• A. 100 mm Hg
• B. 300 mm Hg
• C. 400 mm Hg
• D. 200 mm Hg

Answer: (B)

When testing a mechanical suction unit, you’re verifying that it can generate enough negative pressure to effectively clear airway secretions. Clamping the tubing blocks airflow so the device’s vacuum isn’t diminished by the load and you can read the unit’s true suction capability. The standard minimum you’re checking for is about three hundred millimeters of mercury. This level is considered sufficient to reliably suction secretions without requiring unusually high effort, and it helps ensure the device will work in real patient scenarios. Values well below that threshold (around the hundred or two hundred range) might fail to remove thick mucus, while higher readings (such as four hundred) are acceptable but represent more than the minimum needed. If the unit cannot reach at least three hundred, it should be serviced or repaired before use.