An apparatus for providing pressurized ventilatory assistance to a patient comprises a ventilatory device for delivering pressure support ventilation to a patient； a controller for regulating the pressure support adjustment rate of the delivered ventilation； a sensor for measuring respiratory flow； and a filter for filtering the respiratory flow so as to estimate an uncompensated for leak. The controller is programmed for regulating the pressure support adjustment ate as a function of the estimated uncompensated-for leak.
