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Carbon Monoxide Poisoning

General Considerations

  • Leading cause of accidental poisoning deaths in the United States
  • Most fatalities result from fires, malfunctioning stoves, exhaust systems, heaters, suicide attempts
  • Impairs oxygen delivery and has its most lethal effects on organs requiring high levels of oxygen, i.e. the brain and heart
  • Binds reversibly to hemoglobin much more avidly than oxygen (200-250 times more avidly) leading to high levels of carboxyhemoglobin
  • It also binds to myoglobin with an even greater affinity than to hemoglobin
  • Populations at risk for mortality are those over the age of 75, those with underlying cardiopulmonary disorders, neonates and the fetus in utero
  • Pathology in brain
  • White matter demyelination
  • Edema and necrosis bilaterally in the globus pallidus, caudate nucleus and cerebellum

Clinical findings

  • May be subtle and suggest merely a viral illness
  • Headaches, confusion, chest pain, nausea and vomiting, drowsiness, memory impairment, agitation
  • Cherry red skin is not often present

Imaging findings

  • Non-cardiogenic pulmonary edema
  • CT may be positive within 24 hours and MRI even sooner
  • Characteristic finding is bilaterally symmetric low attenuation lesions in the globus palladi
  • There may also be low density lesions in the cerebral and cerebellar white matter, sparing subcortical fibers
  • Positive CT findings herald long-term neurologic complications occasionally following a period of lucidity that lasts from days to weeks
    • High intensity on T2 in the corpus callosum, internal and external capsules and low intensity signal on T2 in thalamus and putamen (from iron deposition)
  • On MRI, CO poisoning produces low or high signal intensity lesions on T1 and high intensity on T2 in the globus pallidus

Differential Diagnosis

  • Carbon monoxide poisoning has a predilection for affecting the globus pallidus; hypoxic-anoxic injuries additionally involve the caudate nucleus and other central gray nuclei
  • Wilson’s disease may have hypodensities in the basal ganglia and thalami
  • Cyanide can produce globus pallidus infarctions and early diffuse cerebral edema


  • 100% oxygen
  • Hyperbaric oxygen treatment remains controversial

carbon monoxide poisoning

Carbon monoxide poisoning. Unenhanced CT scan of the brain about 16 hours after injury shows bilaterally symmetrical low attenuation lesions in the cerebellum (blue arrows), globus pallidus (red arrows) and caudate nuclei (white arrows). The patient's space heater malfunctioned.
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eMedicine   Carbon Monoxide Toxicity Guy Shochat, MD and Michael Lucchesi, MD