Carbon Monoxide Poisoning

CO is the predominant toxic gas in smoke. (COHb can reach 10% in tobacco smokers.)

CO poisoning is a major cause of death (early symptoms may be only headache and dizziness).

CO is produced by all internal combustion engines, incomplete oxidative combustion (e.g., house fires, charcoal and gas grills, malfunctioning butane/propane stoves), and endogenous sources (e.g., by the liver from exogenous exposure to paint stripper).

No odor, taste, or color and causes no irritation.

Toxicity potentiated by low inspired O ₂ concentration (e.g., smoke inhalation).

To minimize CO in circle circuit carbon dioxide absorbers, use fresh soda lime, use sevoflurane, and minimize drying (lower FGF and stop FGF during use).

During GA, use semiclosed circuits, especially when machine has not been used for 2–3 d (e.g., Monday morning).

Main target organs: Heart and brain

Heart: Effect can resemble ischemia; potentiated by CAD.

Brain: Acute loss of consciousness; after initial improvement (lucid window), up to 30% risk of secondary syndrome: chronic psychiatric dysfunction and cerebral and cerebellar syndromes.

Seek other smoke inhalation injury.

Consider concomitant cyanide poisoning, which potentiates CO toxicity.

Be alert for CO poisoning in donor for organ transplantation.

CO, a colorless, nonirritating, odorless gas, is a natural byproduct of combustion.

CO binds avidly to Hgb (>200 times more than O ₂ ) to form COHb, which carries no O ₂ and causes a left shift in the oxyhemoglobin dissociation curve (decreases O ₂ off-loading to tissues).

CO binds to intracellular hemoproteins such as myoglobin and cytochrome aa ₃ (esp cardiac) to inhibit O ₂ uptake and metabolism.

”Classic” cherry-red complexion rarely observed (need COHb >40%; may be obscured by coexistent hypoxia and cyanosis).

COHb level correlates poorly with clinical condition (symptoms with “normal” COHb).

Treatment should be guided by symptoms and signs, not by blood COHb concentration.

CO produced by incomplete oxidative combustion (e.g., house fires, malfunctioning butane/propane stoves, home heaters, all internal combustion engines)

Suicide attempts