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==Overview== | ==Overview== | ||
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*Initial management of [[methemoglobinemia]] patients includes administration of supplemental [[oxygen]] and if the toxin is still present on the skin, the clothes should be promptly removed and the skin washed. If the patient cannot provide information on the cause of the presenting symptoms, we could check the blood levels of [[MetHb]] and also perform [[gastric lavage]]. In asymptomatic patients, we can measure the serum levels of MetHb multiple times until the levels normalize, which usually happens.<ref name="pmid19082413">{{cite journal| author=do Nascimento TS, Pereira RO, de Mello HL, Costa J| title=Methemoglobinemia: from diagnosis to treatment. | journal=Rev Bras Anestesiol | year= 2008 | volume= 58 | issue= 6 | pages= 651-64 | pmid=19082413 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19082413 }} </ref> <ref name="pmid22024786">{{cite journal| author=Skold A, Cosco DL, Klein R| title=Methemoglobinemia: pathogenesis, diagnosis, and management. | journal=South Med J | year= 2011 | volume= 104 | issue= 11 | pages= 757-61 | pmid=22024786 | doi=10.1097/SMJ.0b013e318232139f | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22024786 }} </ref> | *Initial management of [[methemoglobinemia]] patients includes administration of supplemental [[oxygen]] and if the toxin is still present on the skin, the clothes should be promptly removed and the skin washed. If the patient cannot provide information on the cause of the presenting symptoms, we could check the blood levels of [[MetHb]] and also perform [[gastric lavage]]. In asymptomatic patients, we can measure the serum levels of MetHb multiple times until the levels normalize, which usually happens.<ref name="pmid19082413">{{cite journal| author=do Nascimento TS, Pereira RO, de Mello HL, Costa J| title=Methemoglobinemia: from diagnosis to treatment. | journal=Rev Bras Anestesiol | year= 2008 | volume= 58 | issue= 6 | pages= 651-64 | pmid=19082413 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19082413 }} </ref> <ref name="pmid22024786">{{cite journal| author=Skold A, Cosco DL, Klein R| title=Methemoglobinemia: pathogenesis, diagnosis, and management. | journal=South Med J | year= 2011 | volume= 104 | issue= 11 | pages= 757-61 | pmid=22024786 | doi=10.1097/SMJ.0b013e318232139f | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22024786 }} </ref> | ||
*Patients who are symptomatic and have [[MetHb]] levels above 20% or less than 20% but with multiple comorbidities, should be admitted to the hospital and treated with intravenous (IV) [[methylene blue]] as this is the first-line [[antidotal]] agent, 1% solution (10mg/ml) 1-2mg/kg administered intravenously slowly over five minutes followed by IV flush with [[normal saline]]. [[Methylene blue]] restores the iron in [[hemoglobin]] to its normal ([[reduced]]) oxygen-carrying state. This is achieved through the [[enzyme induction|enzyme inducing]] effect of [[methylene blue]] on levels of [[diaphorase II]] ([[NADPH methemoglobin reductase]]). [[Diaphorase II]] normally contributes only a small percentage of the [[red blood cells | *Patients who are symptomatic and have [[MetHb]] levels above 20% or less than 20% but with multiple comorbidities, should be admitted to the hospital and treated with intravenous (IV) [[methylene blue]] as this is the first-line [[antidotal]] agent, 1% solution (10mg/ml) 1-2mg/kg administered intravenously slowly over five minutes followed by IV flush with [[normal saline]]. [[Methylene blue]] restores the iron in [[hemoglobin]] to its normal ([[reduced]]) oxygen-carrying state. This is achieved through the [[enzyme induction|enzyme inducing]] effect of [[methylene blue]] on levels of [[diaphorase II]] ([[NADPH methemoglobin reductase]]). [[Diaphorase II]] normally contributes only a small percentage of the [[red blood cells]] reducing capacity but is pharmacologically activated by exogenous cofactors, such as [[methylene blue]], to 5 times its normal level of activity.<ref name="pmid21954509">{{cite journal| author=Ashurst J, Wasson M| title=Methemoglobinemia: a systematic review of the pathophysiology, detection, and treatment. | journal=Del Med J | year= 2011 | volume= 83 | issue= 7 | pages= 203-8 | pmid=21954509 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21954509 }} </ref> | ||
*[[Methylene blue]] should not be used in patients with [[G6PD deficiency]], as the [[antidote]] requires [[G6PD]] to work. The use of [[methylene blue]] in [[G6PD deficient]] patients can lead to [[hemolysis]]. In [[G6PD deficient]] patients we can use [[exchange transfusion]] as treatment. [[Exchange transfusion]] as the name implies, replaces abnormal [[hemoglobin]] with normal [[hemoglobin]] | *[[Methylene blue]] should not be used in patients with [[G6PD deficiency]], as the [[antidote]] requires [[G6PD]] to work. The use of [[methylene blue]] in [[G6PD deficient]] patients can lead to [[hemolysis]]. In [[G6PD deficient]] patients we can use [[exchange transfusion]] as treatment. [[Exchange transfusion]] as the name implies, replaces abnormal [[hemoglobin]] with normal [[hemoglobin]]. We can also use it to treat patients presenting with severe symptoms and unresponsive to [[methylene blue]] treatment.<ref name="pmid29592989">{{cite journal| author=Rehman A, Shehadeh M, Khirfan D, Jones A| title=Severe acute haemolytic anaemia associated with severe methaemoglobinaemia in a G6PD-deficient man. | journal=BMJ Case Rep | year= 2018 | volume= 2018 | issue= | pages= | pmid=29592989 | doi=10.1136/bcr-2017-223369 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29592989 }} </ref> | ||
*The use of [[methylene blue]] is contraindicated in patients concurrently taking [[serotonergic psychiatric drugs]], as the risk for inducing [[serotonin syndrome]] increases. Furthermore, [[methylene blue]] is not used in patients with [[Hemoglobin M]] (Hb M), [[nicotinamide adenine dinucleotide phosphate ([[NADPH]]) methemoglobin reductase]] (ie, [[diaphorase II]] deficiency]] and [[sulfhemoglobinemia]], due to lack of effect. In such cases we can use [[hyperbaric oxygen]] treatment, that allows tissue oxygenation via dissolving [[oxygen]] directly in the [[plasma]]. <ref name="pmid14579544">{{cite journal| author=Bradberry SM| title=Occupational methaemoglobinaemia. Mechanisms of production, features, diagnosis and management including the use of methylene blue. | journal=Toxicol Rev | year= 2003 | volume= 22 | issue= 1 | pages= 13-27 | pmid=14579544 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14579544 }} </ref> | *The use of [[methylene blue]] is contraindicated in patients concurrently taking [[serotonergic psychiatric drugs]], as the risk for inducing [[serotonin syndrome]] increases. Furthermore, [[methylene blue]] is not used in patients with [[Hemoglobin M]] (Hb M), [[nicotinamide adenine dinucleotide phosphate ([[NADPH]]) methemoglobin reductase]] (ie, [[diaphorase II]] deficiency]] and [[sulfhemoglobinemia]], due to lack of effect. In such cases we can use [[hyperbaric oxygen]] treatment, that allows tissue oxygenation via dissolving [[oxygen]] directly in the [[plasma]]. <ref name="pmid14579544">{{cite journal| author=Bradberry SM| title=Occupational methaemoglobinaemia. Mechanisms of production, features, diagnosis and management including the use of methylene blue. | journal=Toxicol Rev | year= 2003 | volume= 22 | issue= 1 | pages= 13-27 | pmid=14579544 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14579544 }} </ref> | ||
Latest revision as of 05:18, 22 January 2019
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aksiniya Stevasarova, M.D.
Overview
Methemoglobinemia should be promptly treated once diagnosed.
Medical Therapy
- Initial management of methemoglobinemia patients includes administration of supplemental oxygen and if the toxin is still present on the skin, the clothes should be promptly removed and the skin washed. If the patient cannot provide information on the cause of the presenting symptoms, we could check the blood levels of MetHb and also perform gastric lavage. In asymptomatic patients, we can measure the serum levels of MetHb multiple times until the levels normalize, which usually happens.[1] [2]
- Patients who are symptomatic and have MetHb levels above 20% or less than 20% but with multiple comorbidities, should be admitted to the hospital and treated with intravenous (IV) methylene blue as this is the first-line antidotal agent, 1% solution (10mg/ml) 1-2mg/kg administered intravenously slowly over five minutes followed by IV flush with normal saline. Methylene blue restores the iron in hemoglobin to its normal (reduced) oxygen-carrying state. This is achieved through the enzyme inducing effect of methylene blue on levels of diaphorase II (NADPH methemoglobin reductase). Diaphorase II normally contributes only a small percentage of the red blood cells reducing capacity but is pharmacologically activated by exogenous cofactors, such as methylene blue, to 5 times its normal level of activity.[3]
- Methylene blue should not be used in patients with G6PD deficiency, as the antidote requires G6PD to work. The use of methylene blue in G6PD deficient patients can lead to hemolysis. In G6PD deficient patients we can use exchange transfusion as treatment. Exchange transfusion as the name implies, replaces abnormal hemoglobin with normal hemoglobin. We can also use it to treat patients presenting with severe symptoms and unresponsive to methylene blue treatment.[4]
- The use of methylene blue is contraindicated in patients concurrently taking serotonergic psychiatric drugs, as the risk for inducing serotonin syndrome increases. Furthermore, methylene blue is not used in patients with Hemoglobin M (Hb M), [[nicotinamide adenine dinucleotide phosphate (NADPH) methemoglobin reductase]] (ie, diaphorase II deficiency]] and sulfhemoglobinemia, due to lack of effect. In such cases we can use hyperbaric oxygen treatment, that allows tissue oxygenation via dissolving oxygen directly in the plasma. [5]
- Genetically induced chronic low-level methemoglobinemia may be treated with oral methylene blue daily, ascorbic acid or riboflavin in order to decrease cyanosis.
References
- ↑ do Nascimento TS, Pereira RO, de Mello HL, Costa J (2008). "Methemoglobinemia: from diagnosis to treatment". Rev Bras Anestesiol. 58 (6): 651–64. PMID 19082413.
- ↑ Skold A, Cosco DL, Klein R (2011). "Methemoglobinemia: pathogenesis, diagnosis, and management". South Med J. 104 (11): 757–61. doi:10.1097/SMJ.0b013e318232139f. PMID 22024786.
- ↑ Ashurst J, Wasson M (2011). "Methemoglobinemia: a systematic review of the pathophysiology, detection, and treatment". Del Med J. 83 (7): 203–8. PMID 21954509.
- ↑ Rehman A, Shehadeh M, Khirfan D, Jones A (2018). "Severe acute haemolytic anaemia associated with severe methaemoglobinaemia in a G6PD-deficient man". BMJ Case Rep. 2018. doi:10.1136/bcr-2017-223369. PMID 29592989.
- ↑ Bradberry SM (2003). "Occupational methaemoglobinaemia. Mechanisms of production, features, diagnosis and management including the use of methylene blue". Toxicol Rev. 22 (1): 13–27. PMID 14579544.