Airway Impedance: A Novel Diagnostic Tool to Predict Extraesophageal Airway Inflammation.

OBJECTIVE: To validate a novel biomarker, airway impedance for extraesophageal disease.

STUDY DESIGN: We prospectively recruited patients with respiratory symptoms undergoing combined endoscopy and direct laryngoscopy for the evaluation of symptoms. The direct laryngoscopy was performed and videotaped for blinded scoring by 3 otolaryngologists and an impedance catheter was placed onto the posterior larynx to obtain measurements. Following this, an endoscopy was performed and impedance measurements and biopsies were taken at 3 esophageal heights. Impedance values were compared within and between patients.

RESULTS: Eighty-eight patients were recruited, of which 73 had complete airway and endoscopic exams. There was no significant correlation between airway impedance values and mean reflux finding scores (r2 = 0.45, P = .07). There was no significant positive correlation between airway impedance and esophageal impedance values (r2 = 0.097-0.138, P > .2). Patients taking proton pump inhibitors had significantly lower mean airway impedance values (706 ± 450 Ω) than patients not taking them (1069 ± 809 Ω, P = .06). Patients who had evidence of aspiration on video fluoroscopic swallow studies had lower airway impedance (871 ± 615 Ω) than patients without aspiration (1247 ± 360 Ω, P = .008). Inhaled steroids did not impact airway impedance levels (P = .7).

CONCLUSIONS: Airway impedance may be an important diagnostic tool to diagnose gastroesophageal reflux or aspiration, eliminating the subjectivity of airway appearance alone.