Toxic effect of carb monx from oth source, undet, sequela

This code signifies a long-term or residual health problem resulting from a past exposure to carbon monoxide originating from a source other than those specifically classified. It indicates that the specific source of the carbon monoxide poisoning is unknown or unidentifiable. The sequela could manifest as neurological deficits, cardiac issues, or other chronic conditions.

Apply this code when documenting a patient presenting with a chronic condition or lasting impairment clearly attributed to a previous carbon monoxide poisoning event. This is appropriate when the initial poisoning occurred in the past, and the specific source of the carbon monoxide exposure could not be determined at that time or is no longer ascertainable.

• Always use this code as a secondary diagnosis, following the code for the specific sequela (e.g., chronic encephalopathy).
• Ensure documentation clearly links the current condition to a past carbon monoxide exposure and indicates the undetermined nature of the source.
• Do not use for acute carbon monoxide poisoning or when the source is known (e.g., motor vehicle exhaust, utility gas).