Patent ID: 8261742

Claim:
A method for adjusting a desired pressure in a positive airway pressure device, the method comprising: a) providing a breathing gas under positive pressure to a patient via a positive airway pressure device based at least in part on a current desired pressure; b) monitoring a characteristic of the breathing gas that is indicative of respiration; c) creating a breathing cycle signal with a first level associated with inhalation and a second level different from the first level and associated with exhalation, the breathing cycle signal being based at least in part on the monitored respiration characteristic; d) performing one or more abnormal breathing checks based at least in part on the monitored respiration characteristic and the breathing cycle signal, wherein one or more abnormal breathing checks comprises a hypopnea check, the hypopnea check comprising: creating a filtered respiration signal based at least in part on bandpass filtering the monitored respiration characteristic; monitoring the breathing cycle signal; clearing a positive surge counter and a negative surge counter each time the breathing cycle signal transitions from the second level to the first level to reset the hypopnea check at a start of each breathing cycle; creating a triggered respiration signal with a first level associated with a positive surge and a second level different from the first level and associated with a negative surge, the triggered respiration signal being based at least in part on the filtered respiration signal; monitoring the triggered respiration signal; incrementing the positive surge counter each time the triggered respiration signal transitions from the second level to the first level to count a positive surge after an initial positive surge associated with inhalation; incrementing the negative surge counter each time the triggered respiration signal transitions from the first level to the second level to count a negative surge; reading the positive surge counter and the negative surge counter each time the breathing cycle signal transitions from the first level to the second level; determining if the positive surge count is not equal to zero or the negative surge count is not equal to one; and if either the positive surge count is not equal to zero or the negative surge count is not equal to one, abnormal breathing is detected based on the hypopnea check; and e) if abnormal breathing is detected, increasing the current desired pressure by a first increment until a maximum desired pressure is reached, otherwise, decreasing the current desired pressure by a second increment until a minimum desired pressure is reached.