What are the effects of carbon monoxide (CO) poisoning?

From the Guidelines

Carbon monoxide poisoning is a life-threatening condition that requires immediate medical attention, and treatment typically involves high-flow oxygen therapy and, in severe cases, hyperbaric oxygen therapy to prevent long-term neurocognitive dysfunction and improve outcomes. The effects of carbon monoxide poisoning can be severe and long-lasting, including tissue hypoxia, organ damage, and neurologic sequelae such as memory loss, impairments of concentration or language, affective changes, and parkinsonism 1.

Key Considerations

• Carbon monoxide binds to hemoglobin with an affinity approximately 220 times that of oxygen, impairing delivery of oxygen to tissues and causing tissue hypoxia 1.
• Administration of oxygen, either through a tight-fitting mask or in a hyperbaric oxygen chamber, is crucial in treating carbon monoxide poisoning, as it speeds the elimination of carbon monoxide from the body 1.
• Hyperbaric oxygen therapy may be particularly beneficial for patients with severe carbon monoxide poisoning, including those with significant neurological symptoms, very high carboxyhemoglobin levels, or those who are pregnant or pediatric patients 1.
• The optimal dose and frequency of hyperbaric oxygen treatments for acute carbon monoxide poisoning remain unknown, but it is reasonable to retreat persistently symptomatic patients to a maximum of three treatments 1.

Prevention and Management

• Prevention is crucial, and individuals should install carbon monoxide detectors in their homes, maintain fuel-burning appliances properly, and never use gas-powered equipment or run vehicles in enclosed spaces.
• If carbon monoxide poisoning is suspected, immediate action should be taken to get the individual to fresh air and call emergency services.
• Treatment decisions should be made on a case-by-case basis, taking into account the severity of the poisoning, the patient's overall health, and the availability of hyperbaric oxygen therapy.
• Patients treated for acute accidental carbon monoxide poisoning should be seen in clinical follow-up 1-2 months after the event to monitor for late or evolving cognitive impairments 1.

From the Research

Effects of Carbon Monoxide Poisoning

• The effects of carbon monoxide (CO) poisoning can range from nonspecific symptoms such as dizziness, headache, and angina pectoris to severe symptoms like unconsciousness and death 2, 3, 4, 5.
• CO poisoning can cause reduced oxygen-carrying capacity, impairment of the cellular respiratory chain, and immunomodulatory processes, leading to myocardial and central nervous tissue damage 2, 4.
• The diagnosis of CO poisoning is based on clinical symptoms and proven or probable exposure to CO, and negative carboxyhemoglobin (COHb) levels should not rule out CO poisoning if the history and symptoms are consistent with this phenomenon 2.

Treatment and Management

• The cornerstone of treatment for CO poisoning is 100% oxygen therapy, which should be initiated immediately in the prehospital setting 2, 4, 5.
• Hyperbaric oxygen therapy (HBOT) may be beneficial in severe cases of CO poisoning, but its use is still controversial and should be initiated within 6 hours if required 2, 3, 6.
• Clinical symptoms do not correlate with COHb elimination from the blood, and COHb monitoring alone is unsuitable for treatment management 2.

Delayed Neurological Sequelae

• CO poisoning can lead to delayed neurological sequelae (DNS), which can occur 2-40 days after the initial exposure and may include symptoms such as lethargy, behavior changes, forgetfulness, memory loss, and parkinsonian features 3, 4.
• Seventy-five percent of patients with DNS recover within 1 year, but some may experience persistent neuropsychologic abnormalities and white-matter damage in the brain 4.