A patient receiving continuous positive airway pressure of 7.5 cm H2O via a mask and freestand-ing system appears to be in distress. The patient is using accessory muscles and is diaphoretic

The manometer is fluctuating between –5 cm H2O on inspiration and 7.5 cm H2O on expiration. The most apparent cause of the patient's distress is which of the following?
a. Leak in the system c. Inadequate flow rate
b. Improper mask fit-ting d. Obstruction of the threshold resistor

ANS: C
The patient is pulling in more than the flow of the continuous positive airway pressure system was set to deliver. This is apparent because of the wide fluctuation in the pressures. If there was a leak or improperly fitting mask, the pressure on expiration would not be at the set pressure. If there was an obstruction of the threshold resistor, it would prevent the patient's exhaled gas from exiting and cause the pressure-release valve to pop off.