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Despite eliminating flammable gases such as ether and cyclopropane from operating rooms (ORs), OR fires are just as relevant today as they were when those agents were in use. Fire ignition requires three components, commonly referred to as the fire triad: source, fuel, and an oxidizer. At the molecular level, a fire is a chemical reaction of a fuel plus an oxidizer that produces heat and light. It has been estimated that annually in the United States, there are 50-200 OR fires. To improve patient safety in the OR, the American Society of Anesthesiologists has issued a practice advisory on how to prevent and manage OR fires (Figure 35-1).
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An oxidizer is a substance that removes electrons from another reactant. In the OR, the main oxidizers are O2 and N2O. Closed or semi-closed breathing systems create oxidizer-rich atmospheres that promote combustion.
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Ignition sources are also prevalent in an OR environment. Surgeons often make use of cautery, lasers, argon beams, fiber optic cables, and defibrillator pads. Any of these devices can be the fire source.
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The OR fuel sources are common on the surgical drapes, gauze pads, antibiotic preparation solution, dressings, and surgical caps and gowns. There are also many fuel sources emanating from the anesthesiologist’s equipment: endotracheal tubes, oxygen masks, nasal cannulae, and suction catheters can readily fuel a fire. Patient hair is another combustible fuel.
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Fires cause burn damage and risk damage from fire byproducts. For example, an endotracheal tube on fire produces damaging substances such as carbon monoxide (CO), cyanide (CN), and hydrogen chloride (HCl).
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LINE ISOLATION MONITOR
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Numerous electrical devices operate in an OR. Electrical power is typically grounded in people’s homes but ungrounded in the OR. This is accomplished by using an isolation transformer to induce a current via electromagnetic induction between the primary circuit coming from the electrical company and the secondary circuit going to the OR. Consequently, the power going to the OR is isolated from ground. To receive a shock, a person needs to make contact between two conductive materials at different voltages, thereby completing a circuit. Since the power going to the OR has no connection to ground, a person can touch one side of the isolated power system and not receive a shock due to the incomplete circuit.
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The line isolation system (transformer and monitor) is designed to protect people from electrocution in the OR by power isolation and continuous monitoring of the isolated power system integrity. It is designed to detect short circuits (or leakage ...