Quick memory:
Blue 24 at 2
White 28 at 4
Yellow 35 at 8
Red 40 at 10
Green 60 at 15

Venturi masks provide a fixed, controlled FiO₂ by entraining room air. They are commonly used when precise oxygen delivery is needed, such as in patients at risk of hypercapnic respiratory failure. Morgan and Mikhail's Clinical Anesthesiology, p. 2508-2509.

For COPD or other hypercapnia-risk patients, common initial options are 24% Venturi at 2-4 L/min or 28% at 4 L/min, then titrate to the prescribed saturation target, often 88%-92%, per the British Thoracic Society emergency oxygen guidance.

Important: Colour codes and exact flow ranges can vary by manufacturer. Always use the FiO₂ and minimum flow printed on that specific Venturi barrel.