Ivacaftor for Acquired CFTR Dysfunction in Chronic Rhinosinusitis

Inclusion Criteria: * 18 years of age * Patient has provided informed consent * Diagnosis of CRS made by one of the investigators * Standard of care CT scan with definitive demonstration of isolated or diffuse mucosal thickening, bone changes, and air fluid levels, obtained within 30 days of treatment * Positive culture of at least one gram negative bacteria (e.g. Pseudomonas, E. coli, Steenotrophomonas) within 30 days prior to testing * Previous surgery with (at least) exposed maxillary and ethmoid sinuses * Ability to perform EDSPD testing such that nasal cavity space and sinus openings are sufficient for catheter placement * Negative pregnancy test for females of childbearing potential within 72 hours of testing and start of study treatment Exclusion Criteria: * \< 18 years of age * Acute illness other than sinusitis within 2 weeks before start of study treatment that, in the opinion of the investigator, would preclude participation * Currently taking medications that are moderate or strong CP3A inhibitors * History of asthma attack requiring emergency room visit or treatment with oral steroids within 2 months prior to study treatment * History of solid organ or hematological transplantation * History of known immunodeficiency, autoimmune or granulomatous disorder * Serum creatinine \> 1.5x upper normal limit * Abnormal liver function, as defined by serum AST \> 2x upper normal limit, serum ALT \> 2x upper normal limit, Alkaline phosphatase \> 2x upper normal limit, Total bilirubin \> 2x upper normal limit * Women who are pregnant or breastfeeding