Blue in the face: Unraveling a hypoxic mystery

Affiliations

Advocate Children's Hospital

Presentation Notes

Clinical Conundrum poster presentation at: Pediatric Hospital Medicine Conference; July 2025; Anaheim, CA.

Abstract

Initial History/Presentation: A 5-year-old recently immigrated male with history of asthma and prior admissions for hypoxia presented to the emergency department for left ear pain. He was noted to have central cyanosis and hypoxia which was attributed to asthma exacerbation and treated with albuterol, steroids, and supplemental oxygen. He was also treated with antibiotics for left acute otitis media. The patient was admitted due to hypoxia requiring supplemental oxygen.

Physical Exam: The patient appeared well-developed and in no acute distress. He was mildly tachycardic but other vital signs were normal. His left tympanic membrane showed erythema and serous fluid. He had normal respiratory effort and clear auscultation of lungs, saturating 88-89% on room air and 90-91% on 1.5 liters of nasal cannula. His skin was noted to be blue-grey colored diffusely.

Diagnostic Evaluation: His respiratory viral panel returned positive for human metapneumovirus and enterovirus/rhinovirus. His complete blood count, complete metabolic panel, and procalcitonin were all within normal limits. His hemoglobin electrophoresis was normal. A G6PD level was mildly high at 17 .2 U/g Hb. The patient’s methemoglobin levels were elevated on blood gas and serum testing at 13.6% and 9.8% respectively. His cytochrome B5 reductase level was low at 3.2%.

Diagnosis/Treatment: The patient’s hypoxia and cyanosis were initially attributed to asthma exacerbation, but further evaluation was pursued due to persistent symptoms in the absence of respiratory distress. Furthermore, increases in nasal cannula flow rate did not improve the patient’s cyanosis or hypoxia . Additional laboratory workup revealed an elevated methemoglobin level, which combined with cytochrome B5 reductase deficiency confirmed the diagnosis of congenital methemoglobinemia. Upon identifying the cause of his persistent hypoxia, his oxygen saturation goals were modified to avoid unnecessary interventions based on inaccurate readings, and he was weaned to room air.

Discussion/Conclusion: Methemoglobinemia, especially congenital forms due to enzyme deficiencies, can present subtly with hypoxia and cyanosis, often misattributed to other respiratory conditions like asthma. Clues to diagnosis may be refractory hypoxemia or a cyanosis-saturation gap. This case emphasizes the importance of recognizing limitations in standard oxygen saturation monitoring when methemoglobin is elevated. Adjusting the oxygen saturation target range in these patients is critical to avoid overtreatment . Early recognition and genetic testing are essential for confirming congenital methemoglobinemia and guiding long-term care.

Type

Poster


 

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