The operating room combines oxygen-enriched atmosphere, electrocautery sparks and alcohol-based skin prep into a surgical fire. The US reports 550-650 OR fires per year. NFPA 99 (Health Care Facilities Code) defines oxygen concentration limits, ignition-source control and personnel training.
Surgical Fire Triangle
- Oxidizer: O2 or N2O (100 percent O2 atmosphere)
- Ignition: electrocautery (Bovie), laser, fiber optic
- Fuel: alcohol prep, drape, patient hair, alcohol-based disinfectant
- All three together ignite in 1-3 seconds
Oxygen-Enriched Atmosphere
- Normal O2: 21 percent
- Oxygen-enriched: >23.5 percent
- OR face mask: accumulates under drape - 80-100 percent
- Solution: endotracheal tube or laryngeal mask
- Minimum FiO2: 30 percent suffices for sedation
NFPA 99 Medical Gas Rules
- Gas storage: detached building, 6 m separation
- Copper pipe: Type K or L, no oil-lubricated work
- Zone valve: per OR, shut-off at door
- Pressure alarm: line +/- 20 percent
- Area alarm: control center + corridor
Ignition Source Management
- Electrocautery: O2 off, 3-min dry time after alcohol prep
- Laser ETT: laser-resistant tube (Mallinckrodt Lasertubus)
- Defib pad: dry - no wet alcohol
- Fiber optic: keep active tip away from drapes
Emergency Response
- Step 1: cut O2 (anesthesiologist)
- Step 2: lift drape, douse burning cloth with water
- Step 3: patient secured, then CO2 extinguisher (5 lb mandatory in OR)
- Training: annual OR fire drill - NFPA 99 18.5.2
OR fire with SprinkCalc
SprinkCalc sizes hospital medical-gas zone valves, CO2 extinguisher placement and line alarm setpoints per NFPA 99.
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Sources & Further Reading
NFPA 99, ECRI Institute Surgical Fire Prevention, APSF, AORN Fire Safety Toolkit. NFPA 99 Health Care Facilities standard.