What is known and objective: Formation of methaemoglobinaemia (MetHb) decreases oxygen capacity in the blood, leading to tissue hypoxia. This condition may be acquired following exposure to certain drugs.
Case summary: A critically ill patient with necrotizing fasciitis unexpectedly developed marked and unexplained MetHb (6.7%). Her digital medication list did not reveal the causative factor. However, deeper exploration showed the use of other compounds (acetone, hydrogen peroxide) not routinely visible on the medication list.
What is new and conclusion: Elevated MetHb likely resulted from high-volume hydrogen peroxide 3% exposure. Clinicians should be cautious rinsing large open wounds with hydrogen peroxide. When MetHb is diagnosed, less familiar compounds, usually not on the medication list, should be considered in the differential diagnosis and extensive hetero-anamnesis is mandatory.
Keywords: MetHb; acetone; hydrogen peroxide; toxicology.
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