Potentially life-threatening emergency
Carbon monoxide poisoning
Alerts and Notices
Synopsis
- Assess neurological status.
- Apply oxygen (nonrebreather is preferred unless endotracheal intubation is required).
- Place patient on cardiopulmonary monitoring.
Carbon monoxide (CO) is a colorless, tasteless, odorless gas that commonly causes both accidental and intentional poisoning. It is produced from the combustion of carbon-containing materials, most frequently from fires, faulty furnaces, and car exhausts. CO binds to the hemoglobin in red blood cells with a 250-fold greater affinity than oxygen. Displacement of oxygen forms carboxyhemoglobin (COHb), which results in tissue hypoxia. A small amount of COHb is normal in the blood, typically up to 2% COHb in nonsmokers and up to 10% COHb in smokers.
Mild exposure to CO may mimic flu-like symptoms, causing headaches, myalgias, dizziness, nausea, or neuropsychological impairment. More extreme exposures can cause confusion, loss of consciousness, coma, or death. Central nervous system (CNS) effects are of high concern, as well as cardiac effect. Although cherry-red skin and mucous membranes have been considered characteristic of CO poisoning, they are not always visible. If an individual is chronically exposed to CO, they may experience persistent headaches, cognitive impairment, more generalized fatigue, and dizziness.
Those subjected to CO poisoning acutely or chronically may experience permanent, long-term neurocognitive deficits, including impairments of memory and cognition, as well as impairments of motor and vestibular function. Neuropsychological effects may also occur, including depression and anxiety. Although improvement may be seen by 6 months or 1 year, these sequelae are mostly irreversible.
Higher short-term mortality is seen in patients with low pH (less than 7.2), in those with loss of consciousness, in those who require intubation, or in those exposed to fire.
Treatment is rooted in excellent supportive care, including prompt removal from the contaminated environment and rapid administration of 100% oxygen administration. After removal of CO from the environment, CO will dissociate from hemoglobin within hours. The half-life of COHb is significantly reduced by administration of 100% oxygen.
Pediatric Patient Considerations: Infants and younger children may experience the effects of CO poisoning before older children and adults in the household. They may be symptomatic at levels less than 10% COHb. Symptoms may be atypical, including seizure, emesis, lethargy, irritability, and poor feeding.
Codes
ICD10CM:T58.94XA – Toxic effect of carbon monoxide from unspecified source, undetermined, initial encounter
SNOMEDCT:
17383000 – Toxic effect of carbon monoxide
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Differential Diagnosis & Pitfalls
- Hypoventilation due to drug ingestion (opiates, alcohol)
- Cyanide poisoning – May occur simultaneously with CO poisoning if the patient suffered from smoke inhalation.
- Methemoglobinemia
- Myocardial infarction
- Other environmental exposures or toxins – Consider other asphyxiant agents relevant to clinical history.
- Infectious syndromes – Consider influenza and viral upper respiratory infections.
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Last Reviewed:03/12/2023
Last Updated:03/26/2023
Last Updated:03/26/2023
Potentially life-threatening emergency
Carbon monoxide poisoning