In the NICU, nasal cannulas almost always deliver warmed, humidified oxygen. The oxygen they deliver can help babies in two ways. First, nasal cannulas provide a small amount of pressure as the oxygen blows into the nose, which can help babies’ lungs to stay inflated and can remind them to breathe. Parents may hear this called “flow” or a certain number of “liters.” Second, they can deliver a higher than normal amount of oxygen to help babies oxygenate their bodies. Regular room air contains 21% oxygen, and the nasal cannulas used in most NICUs can deliver up to pure (100%) oxygen.
When a baby breathes in she gets a mixture of room air and the oxygen from the nasal cannula. The actual oxygen concentration that the baby breathes in is determined by the flow of oxygen through the nasal cannula (lower flow rates deliver less oxygen), the size of the baby (larger babies receive less oxygen into their lungs), and whether or not a special blender is used to mix the oxygen with air.