(1148) An Unexpected Case of Methemoglobinemia

Introduction: Methemoglobin is an oxidized form of hemoglobin that has low oxygen-carrying capacity and is associated with life-threatening complications. Acquired methemoglobinemia results from exposure to substances that causes hemoglobin oxidation, such as medications, fertilizers, or foods with nitrite-based preservatives. Poppers (alkylated nitrites), when excessively inhaled or accidentally ingested due to similarities to energy drinks, can induce severe methemoglobinemia.

Description: A 60-year-old man presented to the emergency center after a motor vehicle collision. Before the accident, the patient had called emergency services stating that he felt strange after consuming an over-the-counter energy shot. On examination, he was hypotensive, tachycardic, and in respiratory distress with an oxygen saturation of 80% with perioral cyanosis. Laboratory tests were unremarkable, except for a positive urine drug screen for benzodiazepines. Chest imaging showed normal parenchyma along with sternal manubrium and costal cartilage fractures secondary to the collision. Due to persistent hypoxemia with worsening perioral cyanosis and decreased level of consciousness, the patient underwent rapid sequence intubation complicated by a brief cardiac arrest secondary to profound hypoxemia requiring ECMO evaluation for further support. Arterial blood gas showed chocolate-colored blood with an elevated methemoglobin level (28.7). The patient received 1 dose of methylene blue with improvement and was successfully extubated the next day.

Discussion: Poppers are liquids containing high amounts of amyl nitrate, a potent vasodilator, and muscle relaxant used recreationally to enhance sexual experiences. Despite FDA warnings, there are cases where people mistakenly consume poppers because their packaging is like energy beverages sold at stores. If methemoglobin levels are higher than 20%, encephalopathy, arrhythmias, and hypotension can occur. Reducing agents like methylene blue, ascorbic acid, or exchange transfusion are mainstays of treatment. This case highlights the importance of obtaining an ABG in ruling out methemoglobinemia as a cause of unexplained hypoxemic respiratory failure as delays in recognizing this abnormality may lead to invasive procedures and imaging that could be avoided with appropriate therapy.