Minimal illumination for direct laryngoscopy and intubation in different ambient light settings

Objectives: This study sought to investigate the minimal laryngoscope illumination required for proper laryngoscopy and intubation in different ambient light settings as determined by paramedics. Methods: Paramedics qualified to intubate patients in the field were recruited to intubate a cadaver embalmed with a minimal fixation technique designed to maintain tissue integrity. All paramedic participants intubated the cadaver under three different ambient light settings representing possible out-of-hospital settings: an outdoor night setting, an indoor setting, and an outdoor day setting. Paramedics were asked to determine the minimal illumination required for intubation of the cadaver under each of these settings. Results: Twenty-three paramedics participated in the study. The mean (±SD) minimal illumination required for intubation was 39.1 (±35.4) lux at the night setting, 92.5 (±57.3) lux at the indoor setting, and 209.7 (±117.4) lux at the day setting. There was a statistically significant difference in minimal illumination required between each of the three light settings (p < 0.0001). Conclusions: Minimal illumination requirements in the out-of-hospital setting may be lower than previously recommended. Ambient light intensity affects this minimal illumination requirement, with brighter ambient light conditions necessitating more laryngoscope light output. Further studies assessing out-of-hospital laryngoscope illumination should consider ambient light conditions.