T71.20XD Asphyxiation due to systemic oxygen deficiency due to low oxygen content in ambient air due to unspecified cause, subsequent encounter

T71.20XD is a billable/specific and POA-exempt diagnosis code from the 2025 ICD-10-CM used to classify the following condition: Asphyxiation due to systemic oxygen deficiency due to low oxygen content in ambient air due to unspecified cause, subsequent encounter.