A portable handheld pressure support system configured to deliver a pressurized flow of breathable gas to the airway of a subject, the pressure support system comprising: (a) a pressure generator configured to generate the pressurized flow of breathable gas; (b) a subject interface configured to communicate the pressurized flow of breathable gas to the airway of the subject; (c) one or more sensors configured to generate output signals conveying information related to one or more gas parameters of the pressurized flow of breathable gas; (d) one or more processors configured to execute computer program modules, the computer program modules comprising: a control module configured to control operation of the pressure generator to generate the pressurized flow of breathable gas based on the output signals from the one or more sensors according to a positive pressure support therapy regime, the positive pressure support therapy regime dictating an inspiratory pressure level and an expiratory pressure level, a hyperinflation module configured to identify hyperinflation during exhalation based on the output signals by comparing a first pressure in the lungs of the subject at the end of a first exhalation to a second pressure in the lungs of the subject at the end of a second inhalation to identify air trapping in the lungs of the subject, and an expiratory pressure module configured to control the pressure generator to adjust, responsive to identification of hyperinflation by the hyperinflation module, the expiratory pressure level to relieve hyperinflation during exhalation; (e) a portable power system configured to power the pressure generator, the one or more sensors, and the one or more processors; (f) a housing configured to contain the pressure generator, the subject-interface, the one or more sensors, the one or more processors, and the power system; and (g) a handle attached to and/or formed by the housing configured to be grasped by the subject to hold the housing in position with respect to the airway of the subject as the pressurized flow of breathable gas is delivered to the airway of the subject. (a) a pressure generator configured to generate the pressurized flow of breathable gas; (b) a subject interface configured to communicate the pressurized flow of breathable gas to the airway of the subject; (c) one or more sensors configured to generate output signals conveying information related to one or more gas parameters of the pressurized flow of breathable gas; (d) one or more processors configured to execute computer program modules, the computer program modules comprising: a control module configured to control operation of the pressure generator to generate the pressurized flow of breathable gas based on the output signals from the one or more sensors according to a positive pressure support therapy regime, the positive pressure support therapy regime dictating an inspiratory pressure level and an expiratory pressure level, a hyperinflation module configured to identify hyperinflation during exhalation based on the output signals by comparing a first pressure in the lungs of the subject at the end of a first exhalation to a second pressure in the lungs of the subject at the end of a second inhalation to identify air trapping in the lungs of the subject, and an expiratory pressure module configured to control the pressure generator to adjust, responsive to identification of hyperinflation by the hyperinflation module, the expiratory pressure level to relieve hyperinflation during exhalation; a control module configured to control operation of the pressure generator to generate the pressurized flow of breathable gas based on the output signals from the one or more sensors according to a positive pressure support therapy regime, the positive pressure support therapy regime dictating an inspiratory pressure level and an expiratory pressure level, a hyperinflation module configured to identify hyperinflation during exhalation based on the output signals by comparing a first pressure in the lungs of the subject at the end of a first exhalation to a second pressure in the lungs of the subject at the end of a second inhalation to identify air trapping in the lungs of the subject, and an expiratory pressure module configured to control the pressure generator to adjust, responsive to identification of hyperinflation by the hyperinflation module, the expiratory pressure level to relieve hyperinflation during exhalation; (e) a portable power system configured to power the pressure generator, the one or more sensors, and the one or more processors; (f) a housing configured to contain the pressure generator, the subject-interface, the one or more sensors, the one or more processors, and the power system; and (g) a handle attached to and/or formed by the housing configured to be grasped by the subject to hold the housing in position with respect to the airway of the subject as the pressurized flow of breathable gas is delivered to the airway of the subject.