A method of operating a ventilator that includes steps of (a) providing a specified ventilation therapy to a patient through a ventilator according to a specification； (b) determining and storing a backup parameter relating to the operation of the ventilator or the breathing of the patient during the step of providing the specified ventilation therapy； (c) determining that an alarm condition exists that indicates a problem with the ventilator that would prevent the ventilator from providing the specified ventilation therapy to the patient according to the specification； and (d) responsive to determining that the alarm condition exists, providing backup ventilation therapy to the patient through the ventilator that is based at least partially on the stored backup parameter. Also, a ventilator that is adapted to perform the method just described.
