Hazard of CO2 laser-induced airway fire in laryngeal surgery: experimental data of contributing factors

Abstract

In carbon dioxide (CO2) laser surgery of the larynx, the potentially dangerous combination of laser-induced heat in an oxygen-enriched atmosphere typically occurs when jet ventilation is used or due to an insufficiently blocked endotracheal tube. Until now, no limitations for safe oxygen concentrations or laser intervals have been established. The aim of this study was to investigate and quantify the factors that may contribute to an airway fire in laryngeal laser surgery. Fat, muscle and cartilage were irradiated with a CO2 laser at 2, 4, 6 and 8 W in five different oxygen concentrations with and without smoke exhaustion. The time to ignition was recorded for each different experimental setup. Fat burnt fastest, followed by cartilage and muscle. The elevation of laser energy or oxygen concentration reduced the time to inflammation of any tissue. The elevation of oxygen by 10 % increases the risk of inflammation more than the elevation of laser power by 2 W. Under smoke exhaustion, inflammation and burning occurred delayed or were even inhibited at lower oxygen concentrations. Lasing in more than 50 % oxygen is comparatively dangerous and can cause airway fire in less than 5 s, especially when laser energies of more than 5 W are applied. In equal or lower than 50 % oxygen, an irradiation interval of 5 s can be considered a comparatively safe time limit to prevent inflammation in laryngeal laser surgery. Smoke exhaustion should always be applied.

Predictors for failure of supraglottic superimposed high‐frequency jet ventilation during upper airway surgery in adult patients; a retrospective cohort study of 224 cases

“…The application of CO 2 laser requires low oxygen concentration of the ventilating gas in order to avoid airway fire; even though, experts do not unanimously agree on this issue . In our practice, we routinely reduce the O 2 concentration of the ventilating gas to lower than 40%.…”

Airway laser procedures in children and the American Society of Anesthesiologists’ Practice Advisory: A survey among pediatric anesthesiologists

“…This view was presented by several respondents in the comment section of this survey. However, it is important to recognize that the patient's own tissue as well as the combustible smoke that forms during laser use can still provide fuel for an airway fire [12]. Lastly, providers may underestimate the time interval required for the FiO 2 to fall to safe limits after discontinuation of oxygen.…”

Anesthetic Challenges During Laser Surgery of the Larynx Part 2. Operating Room Fire

“…Few clinicians would agree to allow laser use in the presence of a FiO 2 level greater than 0.4, or 0.5, which is considered dangerous in in vitro studies. 14 Most want the FiO2 under 0.3 in high-risk fire settings. A 2013 analysis of the ASA Closed Claims database, which dates back to 1985, found that laser fires during general anesthesia occurred with inspired oxygen concentrations greater than 30%.…”