Which Venturi mask color adapter delivers approximately 40% FiO₂ (10-12 L/min)?

• A. Blue - 24% at 2-4 L/min.
• B. Red - 40% at 10-12 L/min.
• C. Yellow - 35% at 8-10 L/min.
• D. Green - 60% at 12-15 L/min.

Answer: (B)

Venturi masks are designed to deliver a precise, fixed fraction of inspired oxygen using color-coded adapters. The adapter size and the jet inside determine how much room air is entrained, so the FiO2 stays around a set value regardless of how hard the patient is breathing.

For an approximate 40% FiO2 at a flow of 10–12 L/min, the red adapter is the one that matches this requirement. The color system maps to specific FiO2/fio2 and flow ranges, so that red corresponds to about 40% at that higher flow.

Context for the other colors helps visualize the range: blue delivers about 24% FiO2 at 2–4 L/min (lower oxygen need, lower flow); yellow delivers around 35% FiO2 at 8–10 L/min; green delivers roughly 60% FiO2 at 12–15 L/min.