# Visibility of video laryngoscope in high-illuminance environment simulating outdoor conditions: effects of screen conditions and polarized sunglasses

## TL;DR

This study examines how polarized sunglasses and screen cleaning affect the visibility of a video laryngoscope in bright outdoor-like conditions.

## Contribution

The study identifies practical interventions to improve video laryngoscope visibility in high-illuminance environments.

## Key findings

- Polarized sunglasses significantly improved visibility compared to no sunglasses.
- Cleaning the monitor screen had a greater impact on visibility than wearing sunglasses alone.
- Combining screen cleaning with sunglasses provided the best visibility improvement.

## Abstract

Video laryngoscopes generally increase the success rate of tracheal intubation and clinical outcome compared to traditional direct laryngoscopes. However, there is a concern that their effectiveness can be compromised in bright outdoor environments. The impact of polarized sunglasses on the visibility of a video laryngoscope in a high-illumination environment simulating outdoor conditions was assessed. Additionally, the effect of screen smudges on screen visibility was examined.

A high-illumination environment was created using artificial light equivalent to daylight outdoors. Twenty-four anesthesiologists participated in this study. A commercially available laryngoscope was utilized to evaluate the visibility of the monitor screen and visualize the larynx. The experiment involved a fixed order sequence, including viewing with the naked eye, wearing sunglasses, cleaning the screen without wearing sunglasses, and cleaning the screen while wearing sunglasses, to evaluate visibility with each intervention. A visual analog scale (VAS) (0–100 mm) was used to evaluate the visibility of the larynx displayed on the screen.

Polarized sunglasses significantly enhanced visibility, with a median VAS score of 12 compared to 5 (P = 0.004). Moreover, cleaning the monitor screen significantly improved visibility more than wearing sunglasses alone, with a median VAS score of 38 compared to 12 (P = 0.002). Additionally, wearing sunglasses after cleaning the monitor screen provided even better visibility compared to only cleaning the screen, with a median VAS score of 57 compared to 38 (P = 0.002).

Based on these findings, it is suggested that when using a video laryngoscope outdoors in sunny conditions, the first step to address impaired visibility should be to clean the screen. Wearing sunglasses, if possible, can also be effective in improving visibility.