High Ambient Oxygen Levels Present Combustion Risks

The use of anesthesia is not unusual during oral surgery, and the risk of surgical fires increases with high oxygen saturation levels.

Practitioners, then, need to establish and follow standards to decrease the risk of combustion, according to researchers from the Riley Hospital for Children/Indiana University School of Dentistry, Indiana University School of Medicine, and Purdue University.

In a controlled environment, under a vented chemical hood, the researchers performed 30 trials at 60%, 80%, and 100% oxygen saturation levels each with flow rates of either 4 or 10 liters per minute to detect latency time to combustion. To mimic the oral cavity, they used a raw chicken carcass, which allowed for the use of an oxygen-supplied tube to be secured and two gauze sponges to be placed for a more realistic surgical setting.

Additionally, a standard electrosurgical tip was inserted to provide an ignition source. The researchers were able to obtain real-time data with a thermometer, dew point hygrometer, and oxygen sensor, which were all connected to a computer during each trial. The readings obtained confirmed that conditions were consistent throughout all trials.

The researchers categorized their data according to specific occurrences during the trials: the time to the first event, the time to the first pop, and the time to the first flash or fire. The total number of fire events increased significantly as the oxygen saturation levels increased. Specifically, saturation levels at 60% were much lower than at 80% or 100%.

Also, there was a correlation between the flow rate and the time to the initial fire event, and the 10-L/min flow rate increased the number of events. Ignitions were significantly higher at 100% than at 60% or 80%. Similarly, ignitions were much higher at the 10-L/min flow rate with 100% oxygen than at the 4-L/min rate. Overall, the higher the oxygen saturation and flow rate, the more likely a surgical fire is to occur.

“This research is interesting and exciting to me because dental anesthesia is something that is becoming more widely used every day but cannot be taken lightly,” said researcher Leah Davis, DMD, resident in the Department of Pediatric Dentistry at the Riley Hospital for Children/Indiana University School of Dentistry. “More research and regulations need to be put in place to make sure all procedures will keep patients safe.”

The study confirms that the previously recommended oxygen saturation levels and flow rates remain safe, the researchers said. However, they suggested that future study is warranted to determine the minimum concentration and flow rates that could cause combustion during oral surgery. The current literature on surgical fires in oral surgery is lacking, they said, and more data points are needed to set a standard of care as more office-based surgeries are occurring.