A system configured to deliver medicament to a subject and to monitor respiratory parameters and/or adherence parameters, the system comprising: a respiratory medicament delivery device configured to combine breathable gas and medicament for delivery to an airway of a subject, wherein the respiratory medicament delivery device includes a valve (16, 83) configured to open responsive to respiratory actuation by the subject; a source of ultrasonic energy (102, 103) configured to emit ultrasonic energy such that at least some emitted ultrasonic energy enters the respiratory medicament delivery device; a sensor configured to generate output signals conveying information related to one or more characteristics of the ultrasonic energy emitted by the source of ultrasonic energy; and one or more processors configured to execute computer program modules, the computer program modules comprising: a parameter determination module configured to determine, based on the generated output signals, a first parameter that indicates energy amplitude of the emitted ultrasonic energy; and a flow module configured to detect one or more flow changes through the valve based on one or more changes of the first parameter, wherein the one or more flow changes are responsive to respiratory actuation by the subject, and wherein the parameter determination module is further configured to determine patient adherence based on the detected one or more flow changes. a respiratory medicament delivery device configured to combine breathable gas and medicament for delivery to an airway of a subject, wherein the respiratory medicament delivery device includes a valve (16, 83) configured to open responsive to respiratory actuation by the subject; a source of ultrasonic energy (102, 103) configured to emit ultrasonic energy such that at least some emitted ultrasonic energy enters the respiratory medicament delivery device; a sensor configured to generate output signals conveying information related to one or more characteristics of the ultrasonic energy emitted by the source of ultrasonic energy; and one or more processors configured to execute computer program modules, the computer program modules comprising: a parameter determination module configured to determine, based on the generated output signals, a first parameter that indicates energy amplitude of the emitted ultrasonic energy; and a flow module configured to detect one or more flow changes through the valve based on one or more changes of the first parameter, wherein the one or more flow changes are responsive to respiratory actuation by the subject, and wherein the parameter determination module is further configured to determine patient adherence based on the detected one or more flow changes. a parameter determination module configured to determine, based on the generated output signals, a first parameter that indicates energy amplitude of the emitted ultrasonic energy; and a flow module configured to detect one or more flow changes through the valve based on one or more changes of the first parameter, wherein the one or more flow changes are responsive to respiratory actuation by the subject, and wherein the parameter determination module is further configured to determine patient adherence based on the detected one or more flow changes.