| Summary: | <p>Abstract</p> <p>Introduction</p> <p>Methemoglobinemia is a rare cause of hypoxemia, characterized by abnormal levels of oxidized hemoglobin that cannot bind to and transport oxygen.</p> <p>Case presentation</p> <p>A 62-year-old male underwent bronchoscopy where lidocaine oral solution and Hurricaine spray (20% benzocaine) were used. He developed central cyanosis and his oxygen saturation was 85% via pulse oximetry. An arterial blood gas revealed pH 7.45, P<sub>CO2 </sub>42, P<sub>O2 </sub>282, oxygen saturation 85%. Co-oximetry performed revealed a methemoglobin level of 17.5% (normal 0.6–2.5%). The patient was continued on 15 L/minute nonrebreathing face mask and subsequent oxygen saturation improved to 92% within two hours. With hemodynamic stability and improved SpO<sub>2</sub>, treatment with methylene blue was withheld.</p> <p>Conclusion</p> <p>Methemoglobinemia is a potentially lethal condition after exposure to routinely used drugs. Physicians should be aware of this complication for early diagnosis and treatment.</p>
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