Low-Flow Devices
A nasal cannula delivers about 24 to 44 percent oxygen at 1 to 6 liters per minute and is appropriate for patients with mild hypoxia who tolerate it. A non-rebreather mask at 10 to 15 liters per minute delivers up to 90 percent or more when the reservoir remains inflated.
Selecting the Right Device
Choose based on the patient's presentation, not just the pulse oximetry reading. A patient in respiratory distress with signs of hypoxia such as cyanosis, altered mental status, or accessory muscle use needs high-flow oxygen. A patient who cannot tolerate a mask may do better with a nasal cannula.
Common Exam Points
Always prefill the reservoir of a non-rebreather before placing it on the patient. If breathing is inadequate, no oxygen device is enough, and the patient needs positive pressure ventilation with a BVM. Remember that oxygen is a drug, so give it when indicated and titrate to a target saturation when appropriate.