Oxygen delivery systems are a critical component of patient care in hospitals, especially in critical settings like operating rooms (ORs) and intensive care units (ICUs). They are used to treat respiratory ailments, administer anesthesia, and support patients in respiratory distress, including those with conditions like COVID-19. The two main types of oxygen delivery systems are open and closed systems, each with inherent risks and safety concerns. Open oxygen delivery systems, which include methods like nasal cannulas and face masks, present a higher risk of fire hazards due to the unconfined nature of oxygen flow and the increased likelihood of creating an oxygen-enriched environment.
Open oxygen delivery systems allow oxygen to flow freely into the surrounding environment. Common devices used in open systems include:
Nasal cannulas: A lightweight tube delivering oxygen through the nostrils.
Face masks: Used to provide a higher concentration of oxygen to the patient.
These devices deliver oxygen without forming a sealed barrier between the patient and the environment, allowing oxygen to disperse into the room. This can increase the ambient oxygen concentration in the immediate vicinity of the patient and potentially throughout the entire room.
Fire Risks in Open Oxygen Systems
One of the major concerns with open oxygen delivery systems is the heightened risk of fire. Oxygen is an oxidizer, meaning it can accelerate combustion when in contact with a heat or ignition source. Under normal conditions, the air we breathe contains approximately 21% oxygen, but in open oxygen delivery systems, local concentrations can rise significantly, sometimes exceeding 30%. Even materials that are not normally flammable, such as certain metals and fabrics, can ignite or burn more vigorously in these oxygen-enriched atmospheres.
Oxygen delivery near surgical sites, particularly in the head, neck, and chest regions, is especially dangerous. These areas are prone to fire risks due to the proximity of open oxygen sources to potential ignition devices, such as electrosurgical units, lasers, and even fiber optic light cords. According to research, 85% of OR fires occur in these regions, often involving open oxygen delivery during monitored anesthesia care. The combination of supplemental oxygen, heat from surgical devices, and combustible materials (such as surgical drapes, alcohol-based skin preps, or even hair) completes the "fire triangle" (fuel, oxygen, and ignition), creating a dangerous environment for fire.
Increased Flammability of Materials
In oxygen-enriched environments created by open oxygen delivery systems, materials that would normally be non-combustible or fire-resistant in room air can burn rapidly. Items such as surgical drapes, gauze, linens, and even medical devices made of plastics or elastomers can ignite when oxygen concentrations are elevated. The intensity of combustion increases proportionally with oxygen levels, meaning fires that start in these settings can be difficult to control and spread quickly, increasing the risk of serious injury or death.
Flammable substances such as alcohol-based skin preps, oils, or cleaning solvents become even more dangerous in oxygen-rich environments. If oxygen from an open system accumulates under surgical drapes or near these materials, even a small spark can result in a fast-spreading, high-temperature fire that can engulf the operative field.
| Factor | Effect on combustion |
|---|---|
| Ambient air at sea level, about 21% oxygen | Generally safe and not conducive to fire |
| Open delivery into the surgical field | Local concentrations can rise significantly, sometimes exceeding 30% |
| Concentrations above 30% | Nearly all materials in the operating room, even those considered non-flammable under normal conditions, can become combustible |
| Oxygen acting as an oxidizer | Accelerates combustion when it comes into contact with a heat or ignition source |
| Nitrous oxide | Also acts as an oxidizer, so it carries the same concern |
| Materials normally regarded as non-combustible | Ignite or burn more vigorously once the atmosphere is enriched, including certain metals and fabrics |
| Intensity of combustion | Increases proportionally with the oxygen level, so fires spread quickly and are difficult to control |
| Anatomic distribution of fires | 85% of operating room fires occur in the head, neck, and chest, often with open oxygen delivery during monitored anesthesia care |
Ignition Sources and Fire Prevention
Ignition sources, such as electrosurgical units, lasers, or faulty electrical equipment, are common in hospital environments and particularly in the OR. These devices can easily provide the heat or spark needed to ignite a fire when oxygen concentrations are elevated.
To reduce fire risk, hospitals and operating rooms must implement strict safety measures:
Minimize oxygen concentration: When open oxygen systems are used, healthcare providers must titrate the oxygen to the lowest concentration necessary for patient care, ideally below 30%, as recommended by safety organizations like the Joint Commission and the Anesthesia Patient Safety Foundation. This reduces the likelihood of creating a dangerously oxygen-enriched environment.
Proper ventilation: Operating rooms are typically required to have at least 20 air exchanges per hour to prevent oxygen from accumulating to hazardous levels. Ensuring proper room ventilation helps disperse excess oxygen and lowers fire risk.
Suction and scavenging systems: Suction systems designed to remove excess oxygen around the surgical field can be used to prevent oxygen buildup under drapes. These systems reduce ambient oxygen concentrations and thus lower the risk of fire.
