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