#$%^&*AU2010206082B220130627.pdf#####Abstract of the Disclosure A method and apparatus for providing ventilatory assistance to a spontaneously breathing patient. An error signal is computed that is the difference between a function 5 of respiratory airflow over a period of time and a target value. Using a servo loop, air is delivered to the patient at a pressure that is a function of the error signal, the phase of the current breathing cycle, and a loop gain that varies depending on the magnitude of the error signal. The loop gain increases with the magnitude of the error signal, and the gain is greater for error signals below a ventilation target value than for error signals 10 above the ventilation target value. The target value is an alveolar ventilation that takes into account the patient's physiologic dead space. 15 20 281/I/ 8 6 a 0 4p 13 F(t) 4 Switches oi Pmask~t T Controller Interface impeller air inlet FIG. 1
