An apparatus for setting backup support ventilation for a patient includes a processor controlled ventilator, a sensor for sensing patient breathing, and a timer. The apparatus is operated to determine the patient's spontaneous breathing period and the patient's respiratory cycle and to deliver pressure support ventilation 22 to the patient in synchrony with the patient's respiratory cycle. The backup support includes setting 18 a first timing period to be longer than the determined patient's respiratory cycle, delivering first backup ventilatory support 24 upon detecting a lack of spontaneous breathing during a length of time within the first timing period, setting a second timing period 26 that is shorter than the first timing period and delivering a second backup ventilatory support 28 at the end of the second timing period upon detecting 24, 26 a further lack of spontaneous breathing during the second timing period.
