Correct!
5. All of the above

Methylene blue 1 to 2 mg/kg IV infused over five minutes is the treatment of choice for methemoglobinemia (4). In patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, the reducing agent NADPH is not present in sufficient quantity to allow forward the methemoblogin reductase pathway, for which methylene blue is a cofactor. Large doses of oxidizing ascorbic acid can be used in this situation. In methemoglobinemia pulse oximetry is a highly unreliable method of monitoring for hypoxia, with a 6 to 44% underestimate of true hemoglobin saturation. Methemoglobin levels should be monitored for treatment response, repeating doses every hour as necessary.

References

1. Sigell LT, Kapp FT, Fusaro GA, Nelson ED, Falck RS.Popping and snorting volatile nitrites: a current fad for getting high. Am J Psychiatry. 1978 Oct;135(10):1216-8. [CrossRef] [PubMed]
2. Haverkos HW, Kopstein AN, Wilson H, Drotman P. Nitrite inhalants: history, epidemiology, and possible links to AIDS. Environ Health Perspect. 1994 Oct;102(10):858-61. [CrossRef] [PubMed]
3. Durack DT. Opportunistic infections and Kaposi's sarcoma in homosexual men. N Engl J Med. 1981 Dec 10;305(24):1465-7. [CrossRef] [PubMed]
4. Guay J. Methemoglobinemia related to local anesthetics: a summary of 242 episodes. Anesth Analg. 2009 Mar;108(3):837-45. [CrossRef] [PubMed]

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