Which device delivers low-flow oxygen (1-6 L/min)?

• A. Nasal Cannula
• B. Simple Mask
• C. Nonrebreather Mask
• D. Bag-Valve Mask

Answer: (A)

Low-flow oxygen delivery provides oxygen at modest rates, relying on the patient’s own inhalation to determine the final inspired concentration. The nasal cannula fits in the nostrils and delivers oxygen at about 1 to 6 liters per minute. Because of this relatively low flow, the FiO2 provided is modest—roughly in the 24% to mid-40s% range, increasing with flow and the patient’s breathing. It’s comfortable, unobtrusive, and allows talking and eating, making it ideal for mild to moderate oxygen needs and long-term use. In contrast, higher-flow interfaces require much more oxygen flow to function properly: a simple face mask needs around 5 L/min or more to avoid rebreathing and can deliver higher FiO2; a nonrebreather mask uses about 10–15 L/min to keep the reservoir inflated and provides the highest FiO2 among noninvasive options; a bag-valve mask delivers very high flow during manual ventilation and can provide nearly 100% FiO2, but it’s reserved for emergency use.