Chapter 217

Carbon monoxide is one of the most common causes of fatal poisoning in the U.S., by either intentional (suicidal) or accidental exposure, and may be the most common worldwide cause of fatal poisoning.1 Despite a great deal of clinical experience and randomized trials, there remains a great deal of controversy about the ideal approach to managing carbon monoxide exposures.

Exact statistics for carbon monoxide poisoning are difficult to ascertain, mainly due to incomplete reporting and misdiagnosis. Data from the American Association of Poison Control Centers Toxic Exposure Surveillance System in 20052 reported 16,449 exposures, with 66 deaths. However, this information is limited, as many exposures and some deaths are not reported to the local poison control center. It is also unclear how often patients with milder carbon monoxide poisoning are misdiagnosed and thus are not included in the database. Data from the Centers for Disease Control and Prevention paint a much broader picture of exposures than the Toxic Exposure Surveillance System database. The most recent large epidemiologic report from the center on the subject, the 2001–2003 data on non–fire-related carbon monoxide exposures, revealed 480 deaths and 15,200 exposures.3 The incidence of carbon monoxide exposure has not decreased despite more widespread use of carbon monoxide detectors.3,4

In the past, vehicular emissions were the major source of carbon monoxide poisoning in adults. In recent years, nonvehicular sources have become more common as use of catalytic converters has reduced carbon monoxide in vehicular exhaust emissions5 (Table 217-0.1).

Table 217-0.1 Sources of Carbon Monoxide

Peak incidence occurs in the fall and winter months, generally due to increased use of space heaters, wood-burning stoves, charcoal burning for heat, or portable generators without adequate ventilation.3 Whole families may be affected in such exposures. Additional sources of carbon monoxide exposure include air conditioners, portable generators in camping tents, exhausts on motorboats, and from Zamboni® machines used in ice rinks.6–8 Exposures have been reported in persons riding in the back of a pickup truck and riding in a vehicle whose exhaust pipe was occluded by snow.

Carbon monoxide poisoning is probably the most toxic component in smoke inhalation and is a major contributor to fire-related deaths.

One other source for carbon monoxide poisoning is methylene chloride, which is found in varnishes and paint strippers, and is the bubbling fluid in Christmas lights. Routes of exposure are inhalational or by ingestion. Methylene chloride is metabolized in the liver to carbon monoxide. As a result of ongoing methylene chloride metabolism, persistent elevation of serum carboxyhemoglobin (COHb) occurs despite oxygen therapy.9 Time to peak carbon monoxide levels may be 8 ...

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