You note that the air intake ports surrounding the jet of a 35% air-entrainment mask are partially obstructed by the patient's bedding. Which of the following would you expect?

1. Decrease in the device's total output flow
2. Increase in the percent O2 delivered by the device
3. Change in the FiO2 received by the patient
a. 1 and 2 only
b. 2 and 3 only
c. 1 and 3 only
d. 1, 2, and 3

ANS: A
In the presence of flow resistance distal to the jet, the volume of air entrained always decreases. With less air being entrained, total flow output decreases, and the delivered O2 concentration in-creases.