What is the function of the "flow trigger" in a ventilator?

• A. To filter air
• B. To sense patient’s effort based on flow
• C. To provide oxygen enrichment
• D. To measure tidal volume

Answer: (B)

The function of the "flow trigger" in a ventilator is to sense the patient’s effort based on flow. This mechanism detects the initial flow of air that a patient generates when they attempt to inhale. When the flow rate exceeds a preset threshold, it signals the ventilator to assist or take over the breath. This allows for a more responsive and patient-centered approach to ventilation, as it enables the ventilator to accommodate the patient’s spontaneous breathing efforts effectively.

In contrast, filtering air primarily involves removing particulates and contaminants from the air supply, which is not related to flow triggering. Oxygen enrichment, while important in providing the appropriate concentration of oxygen, does not operate based on the flow of air with respect to a patient’s effort. Measuring tidal volume relates to assessing the volume of air inhaled or exhaled in each breath, but it is separate from the mechanisms that trigger or initiate breaths based on patient effort. Therefore, the flow trigger's primary role is directly linked to recognizing the flow that indicates patient inspiratory demand.