Patent ID: 8857430

Claim:
An apparatus for the treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, the apparatus comprising: a controllable source of breathable gas at positive pressure; means for delivering said breathable gas at positive pressure to a subject's airway; means for deriving a measure of respiratory airflow of the subject; and a servo-controller configured to accept an input variable and a reference quantity, and produce an output to bring the value of the input variable towards the value of the reference quantity; wherein (i) said input variable is a measure of instantaneous ventilation, and (ii) said reference quantity is a percentage of a long-term measure of ventilation continuously derived as half the absolute value of the respiratory airflow, the long-term measure of ventilation being low-pass filtered with a time constant that is long compared with the lung-chemoreceptor delay in patients with Cheyne-Stokes breathing or central sleep apnea.