Blue Despite O2: A Rare Case of Methemoglobinemia

First Author(s)

• AM

  Alisha Menon

  Northwell Health - Lenox Hill Hospital
  New York, NY

  Disclosure information not submitted.

  Slides

Co-Author(s)

• AM

  Anu Menon, MD

  Physician
  Lenox Hill Hospital, New York, United States

  Disclosure information not submitted.
• NK

  Niharika Kottapalli, MD

  Resident Physician
  Montefiore Medical Center- Wakefield, United States

  Disclosure information not submitted.

Title: Blue Despite O2- A Rare Case of Methemoglobinemia

Case Report Body:

Introduction: The diagnosis of methemoglobinemia is infrequently thought of in cases of hypoxia, given its rarity. The most common inciting factor is an exposure to oxidizing agents, such as various antibiotics (sulfonamides, trimethoprim, and dapsone), local anesthetics, nitrites, and aniline dyes. This is a case of methemoglobinemia in a patient who was initially treated for COVID 19 with outpatient vitamin infusions.

Description: A 76-year-old man was brought to the emergency department after collapsing at home. He was treated for COVID-19 the week prior with ivermectin and vitamin infusions, however developed high fevers, up to 102 F, with worsening cough and fatigue. On arrival his oxygen saturation was 50%, which improved with non-rebreather. Chest CT revealed multifocal ground glass opacities, consistent with COVID pneumonia. Shortly after admission, a rapid response was initiated as the patient was becoming more hypoxic with worsening altered mental status. Pulse oximetry revealed oxygen saturation of 60%; the patient was quickly intubated and transferred to the intensive care unit – oxygen saturation continued to read 70% despite a FiO2 100%. An arterial blood gas appeared brown in color and revealed a normal paO2 and pCO2. The patient was found to have a methemoglobin level of 21%. The patient underwent exchange transfusion of 7 units, with subsequent resolution of his hypoxia.

Discussion: Methemoglobinemia is a life threatening disorder, and diagnosis is dependent on a high degree of clinical suspicion. Patients typically present with shortness of breath, fatigue, cyanosis, and can ultimately develop loss of consciousness. An arterial blood gas, with its classic chocolate-brown appearance, a normal Po2, and CO-oximetry panel confirms diagnosis. Methemoglobinemia is routinely treated with methylene blue and, in severe cases, requires red cell exchange. There are reports that have shown benefits of high-dose vitamin C for safe and effective treatment of methemoglobinemia in centers with no access to methylene blue, through its anti-oxidant effect. Interestingly, this patient developed this condition after being treated for COVID 19 with vitamin infusions. This case highlights the importance of careful history taking, as certain medications can have unknown and fatal side effects.