Mechanical ventilation in the presence of sleep disordered breathing

A method of a microprocessor for detecting presence of mouth leak associated with use of a blower adapted to provide a flow of air at positive pressure via a nasal patient interface and a delivery tube, the method comprising:

• receiving data representing a signal from a flow sensor that is adapted to monitor the flow of air to the nasal patient interface;
• determining leak flow during a respiratory cycle of a patient from the data representing the signal from the flow sensor;
• calculating a leak volume from the leak flow during an inspiratory portion;
• calculating a leak volume from the leak flow during an expiratory portion;
• and
• generating an indication that a mouth leak event has occurred when leak volume during exhalation exceeds leak volume during inhalation by a threshold.

In apparatus comprising a blower adapted to provide a flow of air at positive pressure for a patient interface via an air delivery tube connecting the blower to the patient interface, a flow sensor adapted to monitor the flow of air to the patient interface, and a microprocessor, a method of detecting presence of mouth leak comprising:

• determining leak flow during an inspiratory portion of the respiratory cycle of the patient from a signal from the flow sensor;
• calculating a leak volume during inspiration from the leak flow during an inspiratory portion;
• determining leak flow during an expiratory portion of the respiratory cycle of the patient;
• calculating a leak volume during exhalation from the leak flow during the expiratory portion;
• and
• flagging that mouth leak has occurred when leak volume during exhalation exceeds leak volume during inhalation by a threshold.