Revisiting Fire Safety Guidelines in CO₂ Laser Airway Surgery.

Abstract

The potential for airway fire during endoscopic laser surgery is well known, typically addressed by reducing FiO₂ levels. This study revisits these established practices in CO₂ laser tubeless airway surgery. Using a cadaveric porcine larynx and lung model, we conducted trials with high-flow (HFV) and jet ventilation. We varied FiO₂ levels and laser power settings to record the onset and number of brief, expansive, and blowtorch flames. Flames were observed in all jet ventilation trials. Multivariable model results showed that increasing laser wattage decreased onset times for expansive/blowtorch flames and increased their frequency (p < 0.05). Increased FiO₂ changes were not significant (p > 0.05). HFV trials revealed no expansive flames at 4 W at 100%, 6 W at 70%, and 10 W at 50% FiO₂. Increasing wattage shortened flame onset and increased frequency across all flames (p < 0.01), while increasing FiO₂ only reduced onset time for brief flames (p < 0.05). Jet ventilation led to higher flame incidence and shorter onset times than HFV (p < 0.05). Fire risk during CO₂ laser surgery in oxygen-rich environments is influenced more by wattage, rather than FiO₂ levels. Jet ventilation consistently produced expansive flames, even at lower FiO₂ levels and wattage, supporting a FiO₂ limit of 30% for this ventilation technique. Our findings support HFV as a potentially safer option for CO₂ laser surgery, with safe zones of 4 W at 100%, 6 W at 70%, and 10 W at 50% FiO₂, provided laser application is under 30 s. Our model's calculation of excess risk from wattage increments can help surgeons assess this fire risk.