Carbon Monoxide Toxicity in Emergency Medicine Clinical Presentation

  • Author: Guy N Shochat, MD; Chief Editor: Asim Tarabar, MD   more...
 
Updated: May 19, 2011
 

History

Misdiagnosis commonly occurs because of the vagueness and broad spectrum of complaints; symptoms often are attributed to a viral illness. Specifically inquiring about possible exposures when considering the diagnosis is important. Any of the following should alert suspicion in the winter months, especially in relation to the previously named sources and when more than one patient in a group or household presents with similar complaints. Symptoms may not correlate well with HbCO levels. For nonfatal nonintentional non – fire-related exposures, the most common symptom was headache (37%) followed by dizziness (18%) and nausea (17%).[4]

  • Acute poisoning
    • Malaise, flulike symptoms, fatigue
    • Dyspnea on exertion
    • Chest pain, palpitations
    • Lethargy
    • Confusion
    • Depression
    • Impulsiveness
    • Distractibility
    • Hallucination, confabulation
    • Agitation
    • Nausea, vomiting, diarrhea
    • Abdominal pain
    • Headache, drowsiness
    • Dizziness, weakness, confusion
    • Visual disturbance, syncope, seizure
    • Fecal and urinary incontinence
    • Memory and gait disturbances
    • Bizarre neurologic symptoms, coma
  • Chronic exposures also present with the above symptoms; however, they may present with loss of dentition, gradual-onset neuropsychiatric symptoms, or, simply, recent impairment of cognitive ability.
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Physical

Physical examination is of limited value. Inhalation injury or burns should always alert the clinician to the possibility of CO exposure.

  • Vital signs
    • Tachycardia
    • Hypertension or hypotension
    • Hyperthermia
    • Marked tachypnea (rare; severe intoxication often associated with mild or no tachypnea)
  • Skin: Classic cherry red skin is rare (ie, "When you're cherry red, you're dead"); pallor is present more often.
  • Ophthalmologic
    • Flame-shaped retinal hemorrhages
    • Bright red retinal veins (a sensitive early sign)
    • Papilledema
    • Homonymous hemianopsia
  • Noncardiogenic pulmonary edema
  • Neurologic and/or neuropsychiatric
    • Patients display memory disturbance (most common), including retrograde and anterograde amnesia with amnestic confabulatory states.
    • Patients may experience emotional lability, impaired judgment, and decreased cognitive ability.
    • Other signs include stupor, coma, gait disturbance, movement disorders, and rigidity.
    • Patients display brisk reflexes, apraxia, agnosia, tic disorders, hearing and vestibular dysfunction, blindness, and psychosis.
    • Long-term exposures or severe acute exposures frequently result in long-term neuropsychiatric sequelae. Additionally, some individuals develop delayed neuropsychiatric symptoms, often after severe intoxications associated with coma.
    • After recovery from the initial incident, patients present several days to weeks later with neuropsychiatric symptoms such as those just described. Two thirds of patients eventually recover completely.
    • MRI changes may remain long after clinical recovery. Predicting and preventing long-term complications and delayed encephalopathy have been the object of recent studies, many of which focus on the role of hyperbaric oxygen therapy.
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Causes

  • Most unintentional fatalities occur in stationary vehicles from preventable causes such as malfunctioning exhaust systems, inadequately ventilated passenger compartments, operation in an enclosed space, and utilization of auxiliary fuel-burning heaters inside a car or camper.
  • Most unintentional automobile-related CO deaths in garages have occurred despite open garage doors or windows, demonstrating the inadequacy of passive ventilation in such situations.
  • Colorado state data revealed that sources of 1149 poisonings were residential furnaces (40%), automobile exhaust (24%), and fires (12%).
  • Furnaces were determined to be the source in 46% of nonfatal CO poisonings but in only 10% of fatal poisonings. This suggests that the role of home heating appliances is prominent in the large group of underreported nonfatal exposures.
  • In the setting of structure fires, CO presents greater risk to firefighters and victims than thermal injury or oxygen deprivation.[8]
  • Most developing countries utilize unvented cookstoves, burning wood, charcoal, animal dung, or agricultural waste. Studies have shown a concurrent rise in HbCO with these types of exposure in developing countries.
  • Boats and houseboats represent a significant and underappreciated source of exposure with multiple case reports and studies. These have been compiled in an NIOSH Web page.[9]
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Contributor Information and Disclosures
Author

Guy N Shochat, MD  Associate Clinical Professor of Emergency Medicine, University of California at San Francisco

Guy N Shochat, MD is a member of the following medical societies: Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Michael Lucchesi, MD  Chair, Associate Professor, Department of Emergency Medicine, State University of New York at Brooklyn

Michael Lucchesi, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Peter MC DeBlieux, MD  Professor of Clinical Medicine and Pediatrics, Section of Pulmonary and Critical Care Medicine, Program Director, Department of Emergency Medicine, Louisiana State University School of Medicine in New Orleans

Peter MC DeBlieux, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Radiological Society of North America, and Society of Critical Care Medicine

Disclosure: Nothing to disclose.

John T VanDeVoort, PharmD  Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

John G Benitez, MD, MPH  Associate Professor, Department of Medicine, Medical Toxicology, Vanderbilt University Medical Center; Managing Director, Tennessee Poison Center

John G Benitez, MD, MPH is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Preventive Medicine, Society for Academic Emergency Medicine, Undersea and Hyperbaric Medical Society, and Wilderness Medical Society

Disclosure: Nothing to disclose.

John D Halamka, MD, MS  Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD  Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

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Monoplace hyperbaric chamber. Courtesy JG Benitez, MD, MPH.
 
 
 
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