Abstract
Airway surgery presents a unique environment for operating room fire to occur. This study aims to explore the factors of combustion when using KTP laser with high flow oxygen in an ex-vivo model. The variables tested were varying tissue type, tissue condition, oxygen concentration, laser setting, and smoke evacuation in a stainless-steel model. Outcome measures were time of lasing to the first spark and/or flame. A multivariate Cox proportional hazard model was used to determine the risk of spark and flame across the different risk factors. For every 10% increase in oxygen concentration above 60% the risk of flame increased by a factor of 2.3. Continuous laser setting at 2.6 W increased the risk by a factor of 72.8. The risk of lasing adipose tissue is 7.3 times higher than that of muscle. Charred tissue increases the risk of flame by a factor of 92.8. Flame occurred without a preceding spark 93.6% of the time. Using KTP laser in the pulsed mode with low wattages, minimising lasing time, reducing the oxygen concentration and avoiding lasing adipose or charred tissue produce a relatively low estimated risk of spark or flame.
Highlights
Airway surgery presents a unique environment for operating room fire to occur
Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) is a method of oxygenating patients in a shared airway setting by delivering oxygen at a high flow rate to the lungs via nasal cannulae without an endotracheal tube
The hazards rate was defined from the Cox proportional hazard model where h0(t) is the baseline hazard function; β is the vector of regression coefficients; X is the vector of observed covariates and Z is the frailty variable
Summary
Airway surgery presents a unique environment for operating room fire to occur. This study aims to explore the factors of combustion when using KTP laser with high flow oxygen in an ex-vivo model. A subsequent study by Stuermer et al confirmed laser power and oxygen concentration as risk factors and identified tissue type (adipose, cartilage, muscle), tissue quality (fresh, charred) and the use of smoke evacuation as additional independent risk factors for combustion in an ex-vivo plexiglass model using C O2 laser[4]. These two studies were conducted using non-humidified oxygen sources at flow rates significantly lower (jet ventilation at 2 bar and low flow rate at 10L/minute) than those generated when using THRIVE (70L/min)[4,16]. It is possible that 100% humidification of the gas mixture and the high flow rate provided by THRIVE reduces the risk of c ombustion[18]
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