The Drug-Induced Respiratory Disease Website
See also under XIVa-b-e. Cyanosis is slate-greay rather that purple. SpO2 is low or spurious/erratic. Cyanosis is resistant to oxygen therapy. SpO2 low or spurious. PaO2 measured by the Clarke electrode is normal. The hallmarks of methemoglobinemia. Diagnosis is confirmed by chocolate-brown color of blood; which does not turn bright red when bubbled with O2 and/or by spectrophotometric measurement of blood methemoglobin (normally <2%). Four-wavelength pulse CO-oxymetry can also measure methemoglobin and COHb. Methemoglobinemia can be life-threatening or fatal if >40%. Treatment is with oxygen and methylene blue. Severe cases may require HBO or exchange transfusion. Oxidant-induced hemolytic anemia can be found in association
Publications
Topical Benzocaine and Methemoglobinemia.
American journal of therapeutics 2017 Sep/Oct;24;e596-e598 — 2017 Sep/Oct — e596-e598
Methemoglobinemia in bronchoscopy: a case series and a review of the literature.
Journal of bronchology & interventional pulmonology 2013 Jul;20;241-6 — 2013 Jul — 241-6
Benzocaine and lidocaine induced methemoglobinemia after bronchoscopy: a case report.
Journal of medical case reports 2008 Jan 23;2;16 — 2008 Jan 23 — 16