Devices, systems, and methods for measuring the diameter of an airway in a human or animal subject are disclosed. The device comprises a flexible catheter body having a proximal end and a distal end. Flexible sizing elements are disposed along and extend approximately orthogonally from the catheter body. The sizing elements have different heights from one another and are configured to fit through the working channel of a bronchoscope. Devices, systems, and methods for redirecting airflow through a lung airway are also disclosed. The method comprises introducing into the airway a catheter comprising a distal end, a proximal end and an elongated portion therebetween, wherein the distal end comprises an airway closing mechanism, and wherein the proximal end comprises an actuator to actuate the airway closing mechanism； and actuating the airway closing mechanism to at least partially close the airway.
