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Intern Emerg Med. 2018 Mar;13(2):223-229. doi: 10.1007/s11739-018-1798-x. Epub 2018 Feb 12.

Clinical chameleons: an emergency medicine focused review of carbon monoxide poisoning.

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Medical Toxicology, Rocky Mountain Poison and Drug Center, Denver Health and Hospital, 1391 Speer Blvd, Denver, CO, 80204, USA.
Department of Emergency Medicine, San Antonio Military Medical Center, 3841 Roger Brooke Dr, Fort Sam Houston, San Antonio, TX, 78234, USA.
Department of Emergency Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA.


Carbon monoxide (CO) is a colorless, odorless gas that is found in the environment, in the home, and in the human body as a normal part of mammalian metabolism. Poisoning from CO, a common exposure, is associated with significant morbidity and mortality if not recognized and treated in a timely manner. This review evaluates the signs and symptoms of CO poisoning, conditions that present similar to CO poisoning, and an approach to the recognition and management for CO poisoning. CO poisoning accounts for thousands of emergency department visits annually. If not promptly recognized and treated, it leads to significant morbidity and mortality. CO poisoning poses a challenge to the emergency physician because it classically presents with non-specific symptoms such as headache, dizziness, nausea, and vomiting. Due to nonspecific presentations, it is easily mistaken for other, more benign diagnoses such as viral infection. The use of specific historical clues such as exposure to non-conventional heat sources or suicide attempts in garages, as well as the use of targeted diagnostic testing with CO-oximetry, can confirm the diagnosis of CO poisoning. Once diagnosed, treatment options range from observation to the use of hyperbaric oxygen. CO poisoning is an elusive diagnosis. This review evaluates the signs and symptoms CO poisoning, common chameleons or mimics, and an approach to management of CO poisoning.


Carbon monoxide; Chameleon; Headache; Hyperbaric oxygen; Vomiting

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