lung conditions are diagnosed and optionally treated using a functional assessment catheter or a functional lung assessment and treatment catheter . a flow restrictive component is initially placed in a bronchus or lung passageway upstream from a diseased lung region . the isolated lung region is then functionally assessed through the catheter , while the flow restrictive component remains in place . if the patient is a good candidate for treatment by occlusive or restrictive treatment techniques , the flow resistive component may be left in place . if the patient is not suitable for such treatment , the flow resistive component may be removed .