Which of the following are disadvantages of the nasal cannula? 1. Pressure necrosis 2. Drying nasal mucosa 3. FIO2 not precise 4. Claustrophobia

a. 1 and 4 c. 1, 2, and 3
b. 1 and 2 d. 2 and 3

ANS: C
With straight prongs, oxygen flow is directed toward the superior aspects of the nasal cavity, thus promoting turbulent flow; with curved prongs, oxygen entering the nose is directed across the nasal turbinate, thus enhancing laminar flow as the gas flows through the nasal cavity. Thus, both types of prongs can cause the aforementioned disadvantages.