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Mitigating the Risk of Spontaneous Surgical Fires During GA Dental Procedures

Anesthesia Progress – Preparing for dental procedures involving general anesthesia (GA) can be daunting, especially considering that 50 to 600 fires per year occur in operating rooms (ORs), and 20% result in serious injury or even death. Spontaneous surgical fires are especially concerning when oxygen concentrations around the procedure site increase to more than 21%—the normal atmospheric level—known as oxygen pooling. In dental procedures, oxygen pooling can happen during sedation or GA- when supplemental oxygen is introduced through a nasal cannula or during administration of nitrous oxide.

To examine the risk of oxygen pooling during dental procedures, researchers from private practice and the Indiana University School of Dentistry in Indianapolis, Indiana, recently published a study in the current issue of Anesthesia Progress. Lead author Rebecca R. Rafla, DMD, MSD, and colleagues lay out two primary objectives: “The first aim of our study was to determine if oxygen concentrations in the oral cavity rise during general anesthesia. A second aim of the study was to determine if the introduction of high-speed intraoral suction during dental procedures affected oxygen pooling in the oropharynx.”

A total of 31 participants (16 male, 15 female), aged between 2 and 6 years, who underwent GA for dental rehabilitation were assessed for oxygen concentration levels around the procedure site, end-tidal CO2, and changes in respiratory rates after the introduction of an uncuffed endotracheal tube (ETT) or nasopharyngeal airway (NPA) and then after high-speed suctioning of the oral cavity. Measurements were taken at the following three time periods:

1. Baseline: The initial 15 seconds after the first high-speed oral cavity suctioning.
2. Dormant period: A 60-second timeframe when no high-speed suction or dental tool was used; taken immediately after baseline.
3. Active period: A 60-second period when high-speed suction and a dental tool were used; taken immediately after the dormant period

Rafla et al. found that oxygen concentrations were higher across all three time periods when a NPA was used: 46% at baseline, 72.1% by the end of the dormant period and 31.2% at the end of the active period. This suggests that oxygen pooling occurred immediately, and the level continued to increase until the high-speed suction was introduced. The ETT group had significantly better oxygen concentration throughout all three measurement points. At baseline, concentrations were 24.1%, then 26.6% for the dormant period and 21.1% at the conclusion of the active period.

The results show that using an ETT for GA procedures is more effective at minimizing oxygen pooling as concentrations remained below the maximum safety limit of 30% at all time points; the NPA technique surpassed this safety level at all time points. They also indicate that employing high-speed intraoral suction was extremely effective in reducing oxygen pooling, and in turn, mitigating spontaneous fire risk in both procedures.

Study researcher Juan F. Yepes, DDS, MD, MPH, MS, DrPH, believes this research is critical because “The risk of spontaneous surgical fire increases as oxygen concentrations in the surgical site rises above the normal atmospheric level (21%). Previously published in vitro findings imply this phenomenon (termed “oxygen pooling”) occurs during dental procedures under sedation and anesthesia; however, it has not been documented in clinical settings. A high oxygen pooling concentration is a serious risk factor for spontaneous surgical fires. We demonstrated that significant oxygen pooling with nasopharyngeal airways occurred before and after high-speed suctioning. Uncuffed endotracheal intubation showed mild pooling, which was reversed to room air ambient oxygen concentrations after one minute of suctioning. Keeping the oxygen pooling low is critical to avoid the risk of spontaneous surgical fires.”

Full text of the article, “Comparison of Oropharyngeal Oxygen Pooling and Suctioning During Intubated and Nonintubated Dental Office-Based Anesthesia,” Anesthesia Progress, Vol. 70, No. 1, 2023, is now available at https://doi.org/10.2344/anpr-70-01-02

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About Anesthesia Progress

Anesthesia Progress is the official publication of the American Dental Society of Anesthesiology (ADSA). The quarterly journal is dedicated to providing a better understanding of the advances being made in the science of pain and anxiety control in dentistry. The journal invites submissions of review articles, reports on clinical techniques, case reports, and conference summaries. To learn more about the ADSA, visit: http://www.adsahome.org/.

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