Methods and apparatus for treatment of respiratory disorders

A method of operating a respiratory treatment apparatus configured to generate a flow of air so as to provide ventilatory support to a patient, the method comprising:

• measuring a property of the flow of air, using a transducer;
• analysing, in a controller, the measured property to estimate an inspiratory volume and an expiratory volume of a breath of the patient;
• calculating, in a controller, a gain dependent on a difference between the estimated inspiratory volume and the estimated expiratory volume;
• and
• servo-controlling, by a controller, a degree of the ventilatory support using the calculated gain to adjust an estimated tidal volume for the patient toward a target tidal volume.

A system for treating a respiratory disorder in a patient, comprising:

• means for generating a flow of air so as to provide ventilatory support to the patient;
• means for generating a signal representing a property of the flow of air;
• means for analysing the signal to estimate an inspiratory volume and an expiratory volume of a breath of the patient;
• and
• means for servo-controlling a degree of the ventilatory support to adjust an estimated tidal volume toward a target tidal volume,
• wherein a gain of the servo-control is dependent on a difference between the estimated inspiratory volume and the estimated expiratory volume.

Apparatus for treating a respiratory disorder in a patient, the apparatus comprising:

• a blower configured to deliver a supply of air that provides ventilatory support to the patient;
• a transducer configured to generate a signal representing a property of the supply of air;
• and
• a controller configured to:
• analyse the signal to estimate an inspiratory volume and an expiratory volume of a breath of the patient;
• and
• adjust servo-control gain based on a difference between the estimated inspiratory volume and the estimated expiratory volume.