Which oxygen delivery device provides the most precise and adjustable FiO2 for general care settings?

• A. Venturi mask
• B. Nasal cannula
• C. Simple face mask
• D. Nonrebreather mask

Answer: (A)

Precise control of FiO2 is essential when you need a predictable oxygen concentration regardless of how the patient is breathing. The Venturi mask is designed to deliver a fixed, known FiO2 through calibrated adapters that blend room air with pure oxygen. Each adapter corresponds to a specific oxygen concentration, so the delivered FiO2 stays consistent even as the patient’s tidal volume or inspiratory flow changes. That makes it the most reliable choice for achieving a precise, adjustable oxygen level in general care.

Nasal cannula provides oxygen more loosely, with FiO2 ranging roughly from 24% to 44% depending on the flow and how the patient breathes, but it’s affected by mouth breathing and varying inspiratory effort, so it’s not as precise. A simple face mask can deliver higher FiO2 than a cannula, but its actual concentration varies with fit, breathing pattern, and flow, making it less predictable. A nonrebreather mask can deliver very high oxygen concentrations, but FiO2 depends on bag inflation and patient breathing; it’s good for short-term, high-oxygen needs, not for precise control over FiO2.