A system configured to adjust the tidal volume of the breathing of a self-ventilating subject, the system comprising: a device configured to provide a pressurized flow of breathable gas in a bi-level positive air pressure (BiPAP) mode to the airway of the self-ventilating subject, wherein a HI level of positive air pressure is delivered to the subject during an inhalation phase of each breathing cycle and a LO level of positive air pressure is delivered to the subject during an exhalation phase of each breathing cycle, and to provide breathing cues to the self-ventilating subject that prompt the self-ventilating subject to breathe such that the tidal volume of the breathing of the self-ventilating subject is greater than or equal to a target tidal volume; one or more sensors that generate one or more output signals conveying information related to one or more gas parameters of a gas breathed by the self-ventilating subject that are related to the tidal volume of the breathing of the self-ventilating subject; and a processor configured to execute one or more modules (30, 32, 34, 36, 38, 40), the one or more modules (30, 32, 34, 36, 38, 40) comprising: a parameter determination module configured to determine a breathing parameter from the one or more output signals generated by the one or more sensors, wherein the breathing parameter is either ( i) the tidal volume of the breathing of the self-ventilating subject, or ( ii) a gas parameter of the gas breathed by the self-ventilating subject that is related to the tidal volume of the breathing of the self-ventilating subject; and a comparison module configured to compare the breathing parameter to a threshold that corresponds to the target tidal volume; characterized in that the breathing cues provided to the self-ventilating subject by the device includes changes to one or more parameters including a pressure, a flow rate and/or a volume of the pressurized flow of breathable gas, and in that the one or more modules further comprises: a control module configured to control the device to adjust the pressure, the flow rate and/or the volume of the pressurized flow of breathable gas from breathing cycle to breathing cycle, said adjustment being made while the pressurized flow of breathable gas is provided to the self-ventilating subject at the HI level or at the LO level, and said adjustment being based on the comparison between the breathing parameter and the threshold by the comparison module. a device configured to provide a pressurized flow of breathable gas in a bi-level positive air pressure (BiPAP) mode to the airway of the self-ventilating subject, wherein a HI level of positive air pressure is delivered to the subject during an inhalation phase of each breathing cycle and a LO level of positive air pressure is delivered to the subject during an exhalation phase of each breathing cycle, and to provide breathing cues to the self-ventilating subject that prompt the self-ventilating subject to breathe such that the tidal volume of the breathing of the self-ventilating subject is greater than or equal to a target tidal volume; one or more sensors that generate one or more output signals conveying information related to one or more gas parameters of a gas breathed by the self-ventilating subject that are related to the tidal volume of the breathing of the self-ventilating subject; and a processor configured to execute one or more modules (30, 32, 34, 36, 38, 40), the one or more modules (30, 32, 34, 36, 38, 40) comprising: a parameter determination module configured to determine a breathing parameter from the one or more output signals generated by the one or more sensors, wherein the breathing parameter is either ( i) the tidal volume of the breathing of the self-ventilating subject, or ( ii) a gas parameter of the gas breathed by the self-ventilating subject that is related to the tidal volume of the breathing of the self-ventilating subject; and a comparison module configured to compare the breathing parameter to a threshold that corresponds to the target tidal volume; a parameter determination module configured to determine a breathing parameter from the one or more output signals generated by the one or more sensors, wherein the breathing parameter is either ( i) the tidal volume of the breathing of the self-ventilating subject, or ( ii) a gas parameter of the gas breathed by the self-ventilating subject that is related to the tidal volume of the breathing of the self-ventilating subject; and a comparison module configured to compare the breathing parameter to a threshold that corresponds to the target tidal volume; characterized in that the breathing cues provided to the self-ventilating subject by the device includes changes to one or more parameters including a pressure, a flow rate and/or a volume of the pressurized flow of breathable gas, and in that the one or more modules further comprises: a control module configured to control the device to adjust the pressure, the flow rate and/or the volume of the pressurized flow of breathable gas from breathing cycle to breathing cycle, said adjustment being made while the pressurized flow of breathable gas is provided to the self-ventilating subject at the HI level or at the LO level, and said adjustment being based on the comparison between the breathing parameter and the threshold by the comparison module.