What is the role of carboxyhemoglobin blood levels in the assessment of smoke inhalation injury?

Updated: Oct 15, 2021
  • Author: Keith A Lafferty, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Answer

Carboxyhemoglobin levels in the blood and the corresponding clinical manifestations are as follows [1] :

  • 0-10% - Usually no symptoms

  • 10-20% - Mild headache, atypical dyspnea

  • 20-30% - Throbbing headache, impaired concentration

  • 30-40% - Severe headache, impaired thinking

  • 40-50% - Confusion, lethargy, syncope

  • 50-60% - Respiratory failure, seizures

  • >70% - Coma, death

Blood carboxyhemoglobin levels may underestimate the degree of CO intoxication because of oxygen administered to the patient before arrival to the hospital. The use of nomograms to extrapolate levels to the time of rescue has been shown to have prognostic value.

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