CFTR and Airway obstruction: Primary structural and physiological changes that occur within the pulmonary system, including low airway surface fluid, attenuated mucociliary clearance, and airway obstruction are caused by mechanisms that impair chloride (Cl−) and sodium (Na+) regulation specifically related to malfunctioning or absent cystic fibrosis transmembrane conductance regulator (CFTR) protein, and impaired epithelial Na+ channel (ENaC) inhibition [2, 7–10].