A patient is being ventilated with pressure-controlled intermittent mandatory ventilation (PC-IMV) of 12 breaths/min. The apnea alarm time setting should be which of the following?

a. 4 seconds
b. 10 seconds
c. 15 seconds
d. 20 seconds

ANS: B
Apnea alarms are usually set so the patient will not miss two consecutive machine breaths (apnea time > total cycle time [TCT] and < [TCT ? 2]). The TCT would be 5 sec/cycle (60 sec/12 breaths/min = 5 sec). Considering that the alarm should be activated after two missed mandatory breaths, then that would be 10 sec or 2 ? TCT.