Toxic effect of hydrogen cyanide, undetermined, sequela

This code signifies the long-term or residual health problems resulting from a past exposure to hydrogen cyanide, where the intent of the exposure (e.g., accidental, intentional self-harm, assault) cannot be determined. These sequelae can manifest as chronic neurological deficits, respiratory issues, or other persistent organ damage.

Apply this code when documenting a patient presenting with a current, lasting condition directly attributable to a previous hydrogen cyanide poisoning, and the circumstances surrounding the original exposure remain unknown or unspecifiable. This is appropriate for follow-up encounters addressing these chronic effects, not the initial acute poisoning.

• Always sequence this sequela code after the code(s) for the specific manifestation(s) of the sequela.
• Ensure documentation clearly links the current condition to a past hydrogen cyanide exposure.
• Do not use this code for acute poisoning; it is exclusively for the late effects.