Operative Fires: Variables Associated with Polymethylmethacrylate Flammability.

Background: Operative fires are rare but unforgettable events, with the potential for devastating outcomes. It is estimated that 650 operating room (OR) fires occur each year in the United States, with the use of electrocautery devices and polymethylmethacrylate (PMMA) as the primary ignition and fuel sources. There are several case reports of OR fires caused by PMMA and electrocautery in the literature, but, to our knowledge, no formal studies have been performed exposing the flammability of PMMA and how PMMA reacts to an electrocautery ignition source.

Methods: We studied the flammability of PMMA with electrocautery as an ignition source in a controlled laboratory setting. We used 2 different brands of PMMA, both with and without antibiotics. The PMMA was prepared according to the manufacturer's guidelines. In our model, which used a cadaveric leg, the PMMA was placed next to a femoral component that is used in total knee arthroplasty (TKA). Electrocautery was applied at 30-second intervals for a total of 15 minutes. Flammability was defined as any visualized spark or flame while using an electrocautery device. The heat resulting from the chemical reaction was recorded every 30 seconds with a thermal imaging camera (TIC). Video recording was used during the experiment to document the flammability events. A total of 108 tests were performed.

Results: PMMA with and without antibiotics proved to be flammable with the use of electrocautery. All flammability occurred within 7 minutes of combining the monomer and the powder. Increased flammability was seen with the use of antibiotic additives.

Conclusions: PMMA was found to be highly flammable in the initial curing period when exposed to electrocautery as an ignition source. When PMMA is ready for application, we recommend that an "electrocautery timeout" be performed, wherein the electrocautery device is removed from the operating field for a minimum of 7 minutes or until the PMMA has fully hardened.