Variability of the Pressure Measurements Exerted by the Tip of Laryngoscope During Laryngeal Sensory Testing: A Clinical Demonstration

Abstract

Clinicians often test laryngeal sensation by touching the laryngeal mucosa with the tip of a flexible laryngoscope. However, the pressure applied to the larynx by using this touch method is unknown, and the expected responses elicited by this method are uncertain. The variability in pressure delivered by clinicians using the touch method was investigated, and the subject responses to the touches were also reported. A fiberoptic pressure sensor passed through the working channel of a laryngoscope, with its tip positioned at the distal port of the channel. Two examiners each tested 8 healthy adults. Each examiner touched the mucosa covering the left arytenoid 3 times. The sensor recorded the pressure exerted by each touch. An investigator noted subject responses to the touches. From the recorded videos, the absence or presence of the laryngeal adductor reflex in response to touch was judged. Pressure values obtained for 46 of the 48 possible samples ranged from 17.9 mmHg to the measurement ceiling of 350.0 mmHg. The most frequently observed response was positive subject report followed by the laryngeal adductor reflex. Pressure applied to the larynx by using the touch method was highly variable, indicating potential diagnostic inaccuracy in determining laryngeal sensory function.