Revisiting Fire Safety Guidelines in CO2 Laser Airway Surgery

Abstract

Introduction: 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.

Materials and methods: 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.

Results: 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).

Conclusion: 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.

Keywords: CO2 laser; FiO2 limit; airway surgery; experimental study; fire risk; microlaryngoscopy; porcine laryngeal model.