Which device delivers a guaranteed oxygen concentration and is often used for patients with unstable COPD?

• A. Nasal Cannula
• B. Simple Face Mask
• C. Non-Rebreather
• D. Venturi Mask

Answer: (D)

The main concept here is delivering a precise, fixed oxygen concentration. A Venturi mask uses calibrated adapters (Venturi valves) that mix room air with oxygen to deliver a specific FiO2 regardless of the patient’s inspiratory effort. This guarantees the exact oxygen concentration and allows careful titration, which is crucial in unstable COPD to avoid both hypoxemia and CO2 retention. Clinicians target a modest, controlled oxygen level (often in the 88–92% SpO2 range for COPD), and the Venturi mask makes this precise delivery possible by selecting the appropriate adapter for the desired FiO2.

Other devices don’t provide that same fixed concentration. A nasal cannula offers a low, variable FiO2 that depends on flow and breathing pattern. A simple face mask delivers a broader, less predictable range of FiO2 that changes with fit and ventilation. A non-rebreather can deliver high oxygen concentrations but relies on a good seal and patient inspiratory effort, so the exact FiO2 isn’t guaranteed and it’s less ideal for fine titration in COPD.