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American Journal of Hematology Dec 2021Methemoglobinemia is a rare disorder associated with oxidization of divalent ferro-iron of hemoglobin (Hb) to ferri-iron of methemoglobin (MetHb). Methemoglobinemia can... (Review)
Review
Methemoglobinemia is a rare disorder associated with oxidization of divalent ferro-iron of hemoglobin (Hb) to ferri-iron of methemoglobin (MetHb). Methemoglobinemia can result from either inherited or acquired processes. Acquired forms are the most common, mainly due to the exposure to substances that cause oxidation of the Hb both directly or indirectly. Inherited forms are due either to autosomal recessive variants in the CYB5R3 gene or to autosomal dominant variants in the globin genes, collectively known as HbM disease. Our recommendations are based on a systematic literature search. A series of questions regarding the key signs and symptoms, the methods for diagnosis, the clinical management in neonatal/childhood/adulthood period, and the therapeutic approach of methemoglobinemia were formulated and the relative recommendations were produced. An agreement was obtained using a Delphi-like approach and the experts panel reached a final consensus >75% of agreement for all the questions.
Topics: Consensus; Diagnosis, Differential; Disease Management; Humans; Methemoglobinemia
PubMed: 34467556
DOI: 10.1002/ajh.26340 -
Journal of Education & Teaching in... Oct 2022The targeted audience for this simulation are emergency medicine providers, including residents as well as advanced practice providers, to properly educate on...
AUDIENCE
The targeted audience for this simulation are emergency medicine providers, including residents as well as advanced practice providers, to properly educate on recognizing, diagnosing, and managing methemoglobinemia.
INTRODUCTION
Methemoglobinemia is a blood disorder characterized by the presence of ferric form of hemoglobin in the blood. This form of hemoglobin can carry oxygen but is unable to release it effectively causing a range of symptoms including headache, dizziness, nausea, and cyanosis. It is rarely congenital and mostly caused by the exposure to oxidizing agents, such as local anesthetics and quinolones.1 Normally, oxygen can bind to hemoglobin while it is in the ferrous state (Fe2+). In cases of methemoglobinemia, the heme iron configuration is converted from ferrous (Fe2+) to ferric (Fe3+), making it unable to bind to oxygen. As a result, normal ferrous hemes experience an increased affinity for oxygen causing a leftward shift in the oxygen dissociation curve. This in turn causes functional anemia due to reduced oxygen carrying capacity.1 Methemoglobinemia can result from exposure to different medications as well as environmental factors and presents like other disease processes including chronic obstructive pulmonary disease exacerbations. Congenital methemoglobinemia due to cytochrome b5 reductase deficiency is very rare, but the actual incidence is not known. Increased frequency of disease has been found in Siberian Yakuts, Athabaskans, Eskimos, and Navajo.2 Although it is also an unusual occurrence, acquired methemoglobinemia is much more frequently encountered than the congenital form.1In a 10-year retrospective study looking at the incidence rate of topical anesthetic-induced methemoglobinemia, it was found that the overall prevalence was 0.035%. A major risk factor was hospitalization at the time of a procedure being performed. An increased risk was also seen with benzocaine-based anesthetics.3.
EDUCATIONAL OBJECTIVES
At the end of this simulation case, participants should be able to: 1) recognize shortness of breath, cyanosis and respiratory distress, and the difference between all of them based on the clinical presentation 2) identify the underlying cause of the condition by conducting a thorough history and physical 3) know how to identify and treat methemoglobinemia by ordering necessary labs and interventions and understand the pathophysiology leading to methemoglobinemia 4) recognize patient's response to treatment and continue to reassess.
EDUCATIONAL METHODS
This is a high-fidelity simulation case that allows participants to evaluate and treat methemoglobinemia in a safe environment. The case is followed by a debriefing and small group discussion to review patient care skills, medical knowledge, interpersonal communication, practice-based learning, and improvement.
RESEARCH METHODS
The educational content and efficacy were evaluated by oral feedback and a debriefing session immediately after completion of the simulation. A 5-point Likert scale was sent out to participants pre-simulation and post-simulation. Questions on the survey included whether they felt confident in their ability to recognize methemoglobinemia, understood the physiology and causes of methemoglobinemia, and felt confident in their ability to treat methemoglobinemia.
RESULTS
Sixteen learners responded to the survey, consisting of EM residents and medical students. Post simulation, approximately 92% of EM residents answered agree or strongly agree in their ability to recognize and treat methemoglobinemia compared to pre-sim survey of about 62.5%. Post-simulation feedback also resulted in positive reception, and learners found it useful to run through an uncommonly seen case in the hospital. Results showed overall improvement in recognition and treatment of methemoglobinemia among residents and medical students.
DISCUSSION
This simulation improved recognition of methemoglobinemia including signs and symptoms associated with it. Proper management and treatment options were included such as administration of methylene blue. Overall, this simulation was helpful in teaching EM residents how to recognize, manage, and treat methemoglobinemia. In addition, post-simulation debriefing allowed further discussion among residents, which they found valuable.
TOPICS
Methemoglobinemia, shortness of breath, cyanosis, respiratory distress, anemia, methemoglobin, oxygen dissociation curve, emergency medicine simulation.
PubMed: 37465138
DOI: 10.21980/J8PH1B -
Cureus Apr 2021Methemoglobinemia occurs as iron in heme is oxidized to its ferric state, resulting in a decreased ability of hemoglobin to bind and release oxygen. Rasburicase is a...
Methemoglobinemia occurs as iron in heme is oxidized to its ferric state, resulting in a decreased ability of hemoglobin to bind and release oxygen. Rasburicase is a recombinant urate-oxidase enzyme used in the prevention of tumor lysis syndrome. Methemoglobinemia can occur as a rare complication of treatment with rasburicase, primarily in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Methylene blue, an agent used for treating methemoglobinemia, should be avoided in patients with G6PD deficiency. In patients with G6PD deficiency, methylene blue is inadequately reduced to its active form, which then causes the methylene blue to further the oxidize the hemoglobin to methemoglobin that can result in hemolysis.
PubMed: 33987056
DOI: 10.7759/cureus.14406 -
Proceedings (Baylor University. Medical... 2022Methemoglobinemia is a blood disorder in which red blood cells contain methemoglobin, a form of hemoglobin that contains iron in its oxidized state, at levels >1%, often...
Methemoglobinemia is a blood disorder in which red blood cells contain methemoglobin, a form of hemoglobin that contains iron in its oxidized state, at levels >1%, often leading to a hypoxic state. It can be acquired or congenital and has been associated with nitrate or nitrite exposure. "Poppers" and "Rush" are slang terms given to drugs of the chemical class called amyl nitrate or isobutyl nitrite, which are typically inhaled and can be found over the counter. They are used with the intention of enhancing sexual performance due to their vasodilator effects, anal sphincter relaxation, and aphrodisia. We report a case of a man who developed methemoglobinemia secondary to "popper" abuse.
PubMed: 35518804
DOI: 10.1080/08998280.2022.2030188 -
Journal of Clinical Medicine Dec 2020Following the outbreak of a novel coronavirus (SARS-CoV-2) associated with pneumonia in China (Corona Virus Disease 2019, COVID-19) at the end of 2019, the world is... (Review)
Review
Following the outbreak of a novel coronavirus (SARS-CoV-2) associated with pneumonia in China (Corona Virus Disease 2019, COVID-19) at the end of 2019, the world is currently facing a global pandemic of infections with SARS-CoV-2 and cases of COVID-19. Since severely ill patients often show elevated methemoglobin (MetHb) and carboxyhemoglobin (COHb) concentrations in their blood as a marker of disease severity, we aimed to summarize the currently available published study results (case reports and cross-sectional studies) on MetHb and COHb concentrations in the blood of COVID-19 patients. To this end, a systematic literature research was performed. For the case of MetHb, seven publications were identified (five case reports and two cross-sectional studies), and for the case of COHb, three studies were found (two cross-sectional studies and one case report). The findings reported in the publications show that an increase in MetHb and COHb can happen in COVID-19 patients, especially in critically ill ones, and that MetHb and COHb can increase to dangerously high levels during the course of the disease in some patients. The medications given to the patient and the patient's glucose-6-phospate dehydrogenase (G6PD) status seem to be important factors determining the severity of the methemoglobinemia and carboxyhemoglobinemia. Therefore, G6PD status should be determined before medications such as hydroxychloroquine are administered. In conclusion, MetHb and COHb can be elevated in COVID-19 patients and should be checked routinely in order to provide adequate medical treatment as well as to avoid misinterpretation of fingertip pulse oximetry readings, which can be inaccurate and unreliable in case of elevated MetHb and COHb levels in the blood.
PubMed: 33375707
DOI: 10.3390/jcm10010050 -
Frontiers in Pharmacology 2022Pneumocystis pneumonia (PCP) is an opportunity acquired infection, which is usually easy to occur in patients with AIDS, organ transplantation, and immunosuppressive... (Review)
Review
Pneumocystis pneumonia (PCP) is an opportunity acquired infection, which is usually easy to occur in patients with AIDS, organ transplantation, and immunosuppressive drugs. The prevention and treatment must be necessary for PCP patients with immunocompromise. And the oxidants are currently a typical regimen, including sulfanilamide, dapsone, primaquine, etc. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked gene-disease that affects about 400 million people worldwide. The lack of G6PD in this population results in a decrease in intracellular glutathione synthesis and a weakening of the detoxification ability of the oxidants. As a result, oxidants can directly damage haemoglobin in red blood cells, inducing methemoglobin and hemolysis. When patients with G6PD deficiency have low immunity, they are prone to PCP infection, so choosing drugs that do not induce hemolysis is essential. There are no clear guidelines to recommend the drug choice of this kind of population at home and abroad. This paper aims to demonstrate the drug choice for PCP patients with G6PD deficiency through theoretical research combined with clinical cases.
PubMed: 36160421
DOI: 10.3389/fphar.2022.957376