A Randomized Controlled Trial Comparing the Effect of Anti-Fog Agents on Flexible Nasendoscopy View

Flexible nasendoscopy (FNE) is an essential part of otolaryngological examination, and accurate visualization of the upper aerodigestive tract is crucial in order to detect pathological findings and guide further management. Fogging of the endoscopic lens poses a threat to picture quality. Studies comparing the efficacy of anti-fog agents for FNE are lacking. The aim of this study was to assess whether the choice of commercial versus natural anti-fog agents versus no anti-fog agents had an impact on picture quality obtained from FNE.

178 patients undergoing assessment for laryngeal pathology were randomly allocated to one of three groups to receive commercial anti-fog spray, natural anti-fog (patient's own saliva), or no anti-fog agent prior to FNE examination. Video recordings of the larynx from each participant were collected, which were independently assessed by two consultant otolaryngologists blinded to the patient groups, with visual analogue scale (VAS) scores assigned as outcome measures, ranging from 0 to 10. The VAS scores were analyzed with one-way ANOVA.

No significant difference in mean VAS scores was observed by either consultant otolaryngologist in picture quality when comparing anti-fog spray, saliva and no agent (ANOVA, P = 0.09 for Consultant A and P = 0.06 for Consultant B). There was inter-rater reliability between Consultant A and B with percentage agreement of 75%.

The choice between commercial anti-fog spray, saliva and no anti-fog agent does not affect view obtained from FNE. This study's findings have the potential to inform FNE guidelines, thereby minimizing the economical and environmental impacts of unnecessary additional equipment.

Level II evidence.