Which device uses a Venturi mechanism to deliver a fixed oxygen concentration by mixing with room air?

Which device uses a Venturi mechanism to deliver a fixed oxygen concentration by mixing with room air?

• A. Venturi mask
• B. Nasal cannula
• C. Pocket mask
• D. Bag-valve-mask with reservoir

Answer: (A)

The device uses the Venturi principle to deliver a fixed oxygen concentration by mixing with room air. It directs oxygen through a narrow jet that creates a region where ambient air is drawn in through entrainment ports. The entrainment ratio is set by a color‑coded adapter, so the resulting gas mixture has a specific, known FiO2 regardless of the patient’s breathing pattern (as long as the total flow meets the patient’s inspiratory demand). That fixed concentration is the key advantage when you need precise oxygen levels. In contrast, other options don’t enforce a set FiO2. A nasal cannula provides oxygen that mixes with room air, but the exact fraction delivered varies with how deeply and rapidly the patient breathes. Pocket masks and bag‑valve‑masks with reservoirs can deliver high oxygen concentrations, but the actual FiO2 depends on how the mask seals, how much the bag is squeezed, and the patient’s breathing, so the concentration isn’t fixed by design.

The device uses the Venturi principle to deliver a fixed oxygen concentration by mixing with room air. It directs oxygen through a narrow jet that creates a region where ambient air is drawn in through entrainment ports. The entrainment ratio is set by a color‑coded adapter, so the resulting gas mixture has a specific, known FiO2 regardless of the patient’s breathing pattern (as long as the total flow meets the patient’s inspiratory demand). That fixed concentration is the key advantage when you need precise oxygen levels.

In contrast, other options don’t enforce a set FiO2. A nasal cannula provides oxygen that mixes with room air, but the exact fraction delivered varies with how deeply and rapidly the patient breathes. Pocket masks and bag‑valve‑masks with reservoirs can deliver high oxygen concentrations, but the actual FiO2 depends on how the mask seals, how much the bag is squeezed, and the patient’s breathing, so the concentration isn’t fixed by design.