|Year : 2019 | Volume
| Issue : 1 | Page : 108-110
Role of red blood cell exchange for treatment of acquired methemoglobinemia in a patient of aniline dye poisoning
Dolly Gohel, Nidhi Bhatnagar, MD Gajjar, Tarak Patel, Nihar Chaudhari
Department of IHBT, B.J. Medical College, Ahmedabad, Gujarat, India
|Date of Web Publication||22-Apr-2019|
Dr. Dolly Gohel
Department of IHBT, B.J. Medical College, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Typical indication for red blood cell (RBC) exchange is sickle cell disease and its related complications. However, one of the miscellaneous indications of RBC exchange is for the patients of methemoglobinemia who are refractory to treatment by methylene blue. Acquired methemoglobinemia is more common than any genetic causes. Acquired methemoglobinemia is caused by toxins that oxidize heme iron, notably nitrate and nitrite-containing compounds. For patients failing to respond to the standard treatment with methylene blue or in whom its use is contraindicated, hyperbaric oxygen or RBC exchange is indicated. We report a case which was refractory to methylene blue.
Keywords: Acquired methemoglobinemia, red blood cell exchange, refractory to methylene blue
|How to cite this article:|
Gohel D, Bhatnagar N, Gajjar M D, Patel T, Chaudhari N. Role of red blood cell exchange for treatment of acquired methemoglobinemia in a patient of aniline dye poisoning. Glob J Transfus Med 2019;4:108-10
|How to cite this URL:|
Gohel D, Bhatnagar N, Gajjar M D, Patel T, Chaudhari N. Role of red blood cell exchange for treatment of acquired methemoglobinemia in a patient of aniline dye poisoning. Glob J Transfus Med [serial online] 2019 [cited 2020 Oct 25];4:108-10. Available from: https://www.gjtmonline.com/text.asp?2019/4/1/108/256773
| Introduction|| |
Erythrocytapheresis/red blood cell (RBC) exchange involves removing of a large number of RBCs from the patient and returning the patient's plasma and platelets along with compatible allogenic donor RBCs. The donor RBCs selected for transfusion should be ABO- and Rh-compatible, relatively fresh (<10 days is preferable to allow maximum in vivo survival) and partially phenotype matched for Rh (C, c, E, e) antigen to avoid future alloimmunization. In general, one red cell volume (RCV) exchange will remove 70% of patient's RBCs (percentage [fraction] of cells remaining of 30%) and two RCV exchange will remove about 90%. Typical indication for RBC exchange is sickle cell disease and its related complications. However, one of the miscellaneous indications of RBC exchange is for the patients of methemoglobinemia who are refractory to treatment by methylene blue. Methemoglobin is generated by oxidation of heme iron moieties to ferric state, causing a characteristic bluish-brown muddy color of blood resembling cyanosis. Methemoglobinemia should be suspected in patients with hypoxic symptoms who appear cyanotic but have PaO2 sufficiently high that hemoglobin should be fully saturated with oxygen. A history of nitrite or other oxidant ingestions may not always be available; some exposures may be unapparent to the patient, and others may result from suicide attempts. The characteristic muddy appearance of freshly drawn blood can be a critical clue. The best diagnostic test is methemoglobin assay. Injectable (intravenous [IV]) 1 mg/kg of methylene blue is effective first line of treatment. We report a case which was refractory to methylene blue.
| Case Report|| |
A 24-year-old conscious male patient presented to the emergency ward with discoloration of skin, cyanosis of nail bed, tongue and conjunctiva, and labored respiration of 14/min. Blood pressure was 100/84 mmHg, pulse rate was 84/min, and oxygen saturation (SpO2) was 87% on air. Immediate intubation and ventilation with 100% oxygen improved SpO2 – 89% only. There was a history of ingestion of 500 mL of crop poison (aniline dye/nitrobenzene) about 6–8 h before admission. Blood samples drawn for arterial-blood gas had a chocolate brown color which did not improve on exposure to 100% oxygen [Table 1]. Methemoglobin level was moderately high (5.5%) than biological reference level (<1.5%).
|Table 1: Blood chemistry parameters of the patient before erythrocytapheresis|
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X-ray of the chest and electrocardiogram were within normal limits. White blood cell count, liver enzymes, serum creatinine, and electrolytes were within normal range. A clinical diagnosis of severe acute acquired methemoglobinemia due to nitrobenzene (aniline dye) poisoning was made.
12 mL (120 mg) of methylene blue (prepared as 1% sterile solution) and ascorbic acid (500 mg) were given intravenously over duration of 10 min (2 mg/kg). This improved his SpO2 – 90% which dropped after 12 h to 83%, when 6 mL (60 mg) IV methylene blue was repeated. Since the patient was not responding well to treatment with methylene blue (SpO2 not improving from 83%), the decision was made to proceed with RBC exchange. Using Fresenius Kabi COM-TEC cell separator, one RBC volume RBC exchange was completed, using eight units of type “A” positive packed RBC (PRBC). After the 88 min long uncomplicated procedure, the patient's SpO2 was 91%, and he felt much better and signs of cyanosis were reduced. The SpO2 dropped again to 88% after 24 h of one cycle of RBC exchange, and decision was made to proceed with the second cycle of RBC exchange. One RBC volume RBC exchange was done the second time, using six units of type “A” positive PRBC. His SpO2 was 97% after 12 h of second cycle of RBC exchange. The patient improved significantly after two cycles of RBC exchange and was discharged on the 5th day on oral iron, folate, and ascorbic acid.
| Discussion|| |
Hereditary methemoglobinemia is a rare recessively inherited disorder due to deficiency of an enzyme, called reduced nicotinamide adenine dinucleotide cytochrome b5 reductase. However, many chemical agents and drugs can induce methemoglobinemia in normal people. Acquired methemoglobinemia is caused notably by nitrate and nitrite-containing compounds, including drugs commonly used in cardiology and anesthesiology [Table 2].
Under the stress of oxidant drugs, severe cyanosis may develop because of methemoglobinemia. Neurologic abnormalities do not respond to methylene blue therapy.,
Methemoglobin has such high oxygen affinity that virtually no oxygen is delivered. Methemoglobinemia often causes symptoms of cerebral ischemia at levels >15%; levels >60% are usually lethal. IV injection of methylene blue is effective emergency therapy. Rapid improvement in cyanosis and methemoglobin level occurs in 30–60 min after methylene blue injection. Transient drop in pulse oximeter arterial SpO2 can be seen following methylene blue injection, as a result of interference by methylene blue with light-wave emission of pulse oximeter. Milder cases and follow-up of severe cases can be treated orally with methylene blue (60 mg three to four times each day) or ascorbic acid (300–600 mg/d). However, methylene blue therapy is not advisable in patients of acquired methemoglobinemia who are taking selective serotonin reuptake inhibitors, as there is concern for the precipitation of serotonin syndrome. In aniline dye-induced methemoglobinemia, methylene blue can couple with oxyhemoglobin to generate free radicals and can produce hemolysis. If there is coexistent glucose-6-phosphate dehydrogenase (G6PD) deficiency, methylene blue is not effective because of lack of NADPH production, and its use may result in hemolysis. Hence, it is also contradicted in patients who are deficient in G6PD. If methylene blue is contraindicated or ineffective, ascorbic acid is often mentioned as an alternative therapy, but its reducing effect is probably too slow to have significant benefit. Exchange transfusion is indicated in severe cases, when both fail. Transfusions equal to or less than the total volume and up to greater than twice the volume have been used. Few cases have been reported similar to our case where RBC exchange has successfully treated patients of acquired methemoglobinemia who are not responding to treatment with methylene blue or where use of methylene blue is contraindicated. One of the cases is of severe toxic methemoglobinemia in a 18-month-old male patient, who was cyanotic and was admitted with SpO2 level of 86% and methemoglobin (MetHb) level of 39.2%. Despite treatment with methylene blue, he continued to be cyanotic and the MetHb level by co-oximetry, as well as that estimated by adding sodium cyanide, remained elevated. In view of refractory methemoglobinemia, single-volume exchange transfusion was performed twice in an interval of 12 h. Following the procedure, the SpO2 increased to 92%, sensorium improved, and MetHb level gradually decreased to 1%. Another case is of a 57-year-old female patient, who came with acute confusion and diaphoresis and was admitted with SpO2 level of 73%–75%. The MetHb level was too high to be quantified. The treatment with methylene blue was contraindicated in this patient, as she was on selective serotonin reuptake inhibitors at the time. In view of this, one cycle of two-volume RBC exchange was performed. After the 108-min uncomplicated procedure, the SpO2 raised to 97% and MetHb level decreased to 5.8%. The RBC exchange transfusion and hyperbaric oxygen therapy are usually reserved for patients who are resistant to standard treatment and for those with severe symptoms.
| Conclusion|| |
Severe methemoglobinemia is a medical emergency. A good history and high level of suspicion is required to make a diagnosis. It should be considered as a differential diagnosis in all patients with cyanosis that is refractory to oxygen therapy, without any prior history of cardiac or respiratory problems. IV methylene blue is the treatment of choice, but in refractory cases, automated exchange transfusion can be tried. For patients failing to respond to standard treatment with methylene blue or in whom its use is contraindicated, hyperbaric oxygen, blood, or RBC exchange is indicated. Case reports on its use in methemoglobinemia are few, and indications are based on anecdotal reports., Automated RBC exchange has been used successfully when methylene blue is ineffective and may be superior to manual one.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]