A respiratory delivery system comprising: a) a holding chamber comprising: an input end; an output end comprising a user interface having an outlet; and an interior volume of space defined between said input and output ends; b) a metered dose inhaler ("MDI") applicator comprising: a housing (23,906) configured to hold an MDI, wherein one or both of the MDI and housing are configured to communicate with the input end of the holding chamber; a lever moveably connected to the housing, wherein the lever is moveable relative to the housing between an at-rest position and an actuation position, wherein the lever is configured to transfer a force applied to the lever to a canister of the MDI and to actuate the MDI to dispense an aerosolized medicine when the lever is moved to the actuation position; characterised in that - the holding chamber comprises a flow indicator moveable in response to inhalation or exhalation or both by a user through said outlet and configured to send a first input signal when the flow indicator is moved; - the metered dose inhaler ("MDI") applicator comprises a sensor disposed on one of the housing or lever, the sensor configured to send a second input signal when the lever is moved to the actuation position; and - the respiratory delivery system comprises: c) a processor operative to receive the first input signal from the flow indicator and the second input signal from the sensor and generate an output signal. a) a holding chamber comprising: an input end; an output end comprising a user interface having an outlet; and an interior volume of space defined between said input and output ends; an input end; an output end comprising a user interface having an outlet; and an interior volume of space defined between said input and output ends; b) a metered dose inhaler ("MDI") applicator comprising: a housing (23,906) configured to hold an MDI, wherein one or both of the MDI and housing are configured to communicate with the input end of the holding chamber; a lever moveably connected to the housing, wherein the lever is moveable relative to the housing between an at-rest position and an actuation position, wherein the lever is configured to transfer a force applied to the lever to a canister of the MDI and to actuate the MDI to dispense an aerosolized medicine when the lever is moved to the actuation position; characterised in that - the holding chamber comprises a flow indicator moveable in response to inhalation or exhalation or both by a user through said outlet and configured to send a first input signal when the flow indicator is moved; - the metered dose inhaler ("MDI") applicator comprises a sensor disposed on one of the housing or lever, the sensor configured to send a second input signal when the lever is moved to the actuation position; and - the respiratory delivery system comprises: c) a processor operative to receive the first input signal from the flow indicator and the second input signal from the sensor and generate an output signal. a housing (23,906) configured to hold an MDI, wherein one or both of the MDI and housing are configured to communicate with the input end of the holding chamber; a lever moveably connected to the housing, wherein the lever is moveable relative to the housing between an at-rest position and an actuation position, wherein the lever is configured to transfer a force applied to the lever to a canister of the MDI and to actuate the MDI to dispense an aerosolized medicine when the lever is moved to the actuation position; characterised in that - the holding chamber comprises a flow indicator moveable in response to inhalation or exhalation or both by a user through said outlet and configured to send a first input signal when the flow indicator is moved; - the metered dose inhaler ("MDI") applicator comprises a sensor disposed on one of the housing or lever, the sensor configured to send a second input signal when the lever is moved to the actuation position; and - the respiratory delivery system comprises: c) a processor operative to receive the first input signal from the flow indicator and the second input signal from the sensor and generate an output signal. - the holding chamber comprises a flow indicator moveable in response to inhalation or exhalation or both by a user through said outlet and configured to send a first input signal when the flow indicator is moved; - the metered dose inhaler ("MDI") applicator comprises a sensor disposed on one of the housing or lever, the sensor configured to send a second input signal when the lever is moved to the actuation position; and - the respiratory delivery system comprises: