#$%^&*AU2009230737B220130307.pdf#####12 ABSTRACT A ventilator device delivers ventilatory support to a patient in a back up timed mode when patient respiration is not detected or a spontaneous mode when patient respiration is detected. The timing threshold governing the back-up mode is chosen to deviate from normal expected respiration time for the patient to promote patient initiated ventilation in the spontaneous mode but permit back-up ventilation in the event of apnea. Automated adjustments to the timing threshold during the timed mode are made from the less vigilant timing threshold to a more vigilant threshold at or near a timing of normal expected breathing of the patient. Such adjustments may be made from a minimum to a maximum vigilance timing settings or incrementally there between as a function of time in the timed mode which is preferably the number of delivered machine breaths. In one embodiment, within the timed mode the device periodically returns the timing threshold to a less vigilant timing threshold to promote resynchronization with the patient. In another embodiment, changes to the timing threshold are made as a function of a determined ventilation adequacy.1/4 6 5 1 P t) Sw itch e s 0 1 Ft 15 Interface Dipas ev 8 3 air inlet FIG. 1
