A ventilator comprising: (a) a housing having an interior and an exterior; (b) an inlet port extending from the exterior to the interior of the housing; (c) a flow generator disposed within the ventilator and being structured to generate a flow of gas; (d) an outlet port for discharging the flow of gas from the housing; (e) a patient circuit (65; 115) in fluid communication with the outlet port and being structured to deliver the flow of gas to an airway of a patient during an inspiratory phase of a ventilatory cycle; and (f) a controller disposed in the housing and being operatively coupled to the flow generator, the controller being adapted to: provide a specified ventilation therapy to a patient through the patient circuit according to a specification, characterised in that the controller is further adapted to: determine and store a backup parameter relating to the operation of the ventilator or the breathing of the patient while the specified ventilation therapy is being provided, determine that an alarm condition exists, wherein the alarm condition 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 provide a backup ventilation therapy to the patient through the patient circuit wherein the backup ventilation therapy is based at least partially on the stored backup parameter. (a) a housing having an interior and an exterior; (b) an inlet port extending from the exterior to the interior of the housing; (c) a flow generator disposed within the ventilator and being structured to generate a flow of gas; (d) an outlet port for discharging the flow of gas from the housing; (e) a patient circuit (65; 115) in fluid communication with the outlet port and being structured to deliver the flow of gas to an airway of a patient during an inspiratory phase of a ventilatory cycle; and (f) a controller disposed in the housing and being operatively coupled to the flow generator, the controller being adapted to: provide a specified ventilation therapy to a patient through the patient circuit according to a specification, characterised in that the controller is further adapted to: determine and store a backup parameter relating to the operation of the ventilator or the breathing of the patient while the specified ventilation therapy is being provided, determine that an alarm condition exists, wherein the alarm condition 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 provide a backup ventilation therapy to the patient through the patient circuit wherein the backup ventilation therapy is based at least partially on the stored backup parameter. provide a specified ventilation therapy to a patient through the patient circuit according to a specification, determine and store a backup parameter relating to the operation of the ventilator or the breathing of the patient while the specified ventilation therapy is being provided, determine that an alarm condition exists, wherein the alarm condition 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 provide a backup ventilation therapy to the patient through the patient circuit wherein the backup ventilation therapy is based at least partially on the stored backup parameter.