(1205) Welcome to the Jungle: Methemoglobinemia in a Patient at High Risk for Serotonin Syndrome

Introduction: Methemoglobinemia (MetHb) is a rare form of hemoglobinopathy that is characterized by persistent oxidation of iron molecules within hemoglobin. Ferric iron decreases the binding capacity of hemoglobin; therefore, leading to hypoxemia. While MetHb can be congenital, it is most often encountered in patients who have had a toxic exposure or who have recently undergone a procedure. The mainstay of MetHB treatment is Methylene Blue (MB), which works to reduce iron back to its ferrous state. MB has been well documented as a powerful instigator of serotonin syndrome in patients who take serotonergic drugs

Description: A 30-year-old female with history of decompensated alcoholic cirrhosis, chronic alcohol and tobacco use, and depression/anxiety (on buspirone, trazodone, and escitalopram) was admitted for evaluation and management of nausea, vomiting, and hematemesis secondary to gastritis and gastrointestinal bleed. On Hospital Day 4 the patient developed hypotension with blood pressure 69/33 mmHg and SpO2 of 86% on room air. When oxygen levels would not improve and the patient continued to appear cyanotic on exam with blue lips, decision was made to transfer patient to medical ICU. Imaging obtained at time of transfer was without any acute findings. An arterial blood gas (ABG) demonstrated pH 7.39, pCO2 40 mmHg, pO2 323 mmHg, Oxyhemoglobin 70%, and MetHb >20%. After extensive conversations, the patient admitted to inhalation of “Jungle Juice,” or amyl nitrate, which prompted development of acute MetHb. Poison control was contacted and recommended discontinuation of buspirone, trazodone, and escitalopram and initiation of low-dose MB with very close-monitoring for signs of serotonin syndrome. After receiving 1 mg/kg dose MB, SpO2 improved to 95% with pO2 100 mmHg, oxyhemoglobin 94%, and MetHb 1.1%.

Discussion: This case demonstrates the effective use of MB for treatment of acute MetHb in a patient who was at high risk for development of serotonin syndrome and suggests that MB should still be considered as a treatment option in patients on serotonergic agents. This case also highlights the importance of a thorough physical exam and close examination of blood gas results, as a toxic ingestion several days into a hospital course could reasonably be missed if MetHb is not in the differential.