How is the level of cyanide (CN) intoxication assessed in the workup of smoke inhalation injury?

Updated: Oct 15, 2021
  • Author: Keith A Lafferty, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Cyanide (CN) levels correlate closely with the level of exposure and toxicity, but these values may not be readily available. Many hospitals send out tests for CN levels, and results may not return for several days to a week. In a setting consistent with potential CN exposure, institute specific empiric therapy while waiting for laboratory confirmation of the diagnosis.

Findings indicative of CN intoxication include the following:

  • Persistent neurologic dysfunction unresponsive to use of supplemental oxygen

  • Cardiac dysfunction

  • Severe lactic acidosis, particularly in the presence of high mixed venous oxygen saturation

  • “Arterialization” of the venous blood gas, with PO2 values similar to arterial levels due to lack of oxygen utilization by tissues

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