Airway Impedance to Objectively Assess Airway Mucosal Integrity

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R Rosen et al. J Pediatr 2023; 256: 5-10. Airway Impedance: A Novel Diagnostic Tool to Predict Extraesophageal Airway Inflammation

Airway appearance is not a reliable marker for aerodigestive disorders. This study (n=73 completed full study) sought to use airway impedance to provide an objective measure of airway mucosal integrity.

Methods: The direct laryngoscopy was performed and videotaped for blinded scoring by 3 otolaryngologists and a specially-designed impedance catheter was placed onto the posterior larynx to obtain measurements; the impedance sensors were placed immediately below vocal cords. Following this, an endoscopy was performed and impedance measurements and biopsies were taken.

Key findings:

  • 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)

Discussion:

  • Low impedance values have been correlated with esophageal inflammation. For example, in patients with active eosinophilic esophagitis impedance values of <1000 Ω are typical compared to >2500-3000 Ω in those without inflammation.
  • This study suggests that low laryngeal impedance prior to EGD can provide an objective marker of laryngeal mucosal integrity. Values were lower in those with impaired swallowing/aspiration. The association with lower values in those taking PPIs may be due to ongoing GERD (acid or nonacid) and/or ongoing pepsin exposure.
  • It is noted that airway impedance values were, “on average, 3-fold lower than esophageal impedance values, highlighting the differences in these microenvironments.”
  • Limitations: No healthy controls

My take: Frequently, aerodigestive patients undergo extensive evaluations. This is a simple technique that could easily be added; it may be an objective marker of airway disorders “and may help reduce acid suppression use previously driven by these visual exams.”

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