A Patient with "Rebound Methemoglobinemia" during Treatment of Methemoglobinemia Caused by Propanil Intoxication

Methemoglobinemia results from the oxidation of ferrous iron (Fe++) to ferric iron (Fe+++) within hemoglobin. It is caused by various etiologies, including the herbicide Propanil. Patients with low levels of methemoglobin (metHb) are asymptomatic but symptomatic patients and patients with high levels of metHb require treatment. Methylene blue is the first choice for the treatment of methemoblobinemia, but has some complications such as hemolytic anemia and rebound methemoglobinemia. We report the case of a 91-year-old woman who died of aniline herbicides poisoning. The level of metHb in her blood was initially 20.7% and her mental status was drowsy. She was intravenously treated with methylene blue within a therapeutic range for methemoglobinemia. After treatment with methylene blue, the level of metHb decreased but later increased above 20%. Methylene blue treatment was repeatedly attempted, but the patient suffered from hemolytic anemia and rebound methemoglobinemia. The patient finally died from renal failure and cardiopulmonary collapse. We must be careful because methemoglobinemia can occur even when treated pesticides such as propranil.

A Patient with Methemoglobinemia after Herbicide Intoxication has Hemolytic Anemia Induced by Methylene Blue

Methylene blue is the first choice for treating methemoglobinemia, any increase in normal methemoglobin levels. Methemoglobin is an abnormal hemoglobin in which the iron has been oxidized to the ferric(+3) state, making it incapable of oxygen transport. Methemoglobinemia most commonly results from exposure to oxidizing chemicals, but may also arise form genetic, dietary, or even idiopathic etiologies. Patients with low methemoglobin levels are asymptomatic, but high methemoglobin levels can lead to headaches or even death. Methylene blue, the first-line treatment for methemoglobinemia, can also produce hemolytic anemia. Jaundice or dark urine during methylene blue treatment may indicate hemolytic anemia. A 47-year-old female patient with a history of depressive mood disorder developed significant methemoglobinemia after ingesting a Propanil overdose. Twenty-two hours after ingestion, methemoglobin levels in the blood were 73.2%. She was treated with intravenous methylene blue in the therapeutic range (1 mg/kg every 4 h for 3days). The 2nd day after methylene blue use, methemoglobin levels in the blood were 33%, and the 5th day decreased to 10% with better general condition. The patient had hyperbilirubinemia after hemolytic anemia, but she recovered completely.

Fatal Propanil Pesticide Poisoning Presenting with Methemoglobinemia

Acute propanil pesticide poisoning is rare and propanil is known to have a low toxicity. Propanil metabolite induces the conversion of Fe2+ in hemoglobin to Fe3+, forming methemoglobin. Patients with low metHb levels are asymptomatic, but severe methemoglobinemia produces headache, dizziness, decreased consciousness, convulsion, and death. Thus, delayed diagnosis in patients with severe methemoglobinemia can be lethal. We describe the case of a 60-year-old man who died of acute propanil pesticide poisoning. He presented with severe methemoglobinemia. Early methylene blue therapy is recommended for propanil pesticide poisoning patients with symptoms and signs of methemoglobinemia.

A Case of Pendipronil(R) Poisoning Treated by Hemoperfusion and Methylene Blue / 대한신장학회잡지

Pendipronil(R) overdose is uncommon in Korea. Pendipronil(R) is a selective herbicide used to control most annual grasses and certain broadleaf weeds in field corn, potatoes, rice, etc. and is the substance including pendimethalin and propanil. Pendimethalin is slightly to practically nontoxic by ingestion but may be mildly to moderately irritating to the linings of the mouth, nose, throat, and lungs. Propanil toxicity is evidenced by varying clinical pictures ranging from deep cyanosis in an otherwise alert normal appearing individual to restlessness, dyspnea, extensive hemolytic anemia, methemoglobinemia, sulfhemoglobinemia and serious central nervous system dysfunction. For the treatment of methemoglobinemia, gastric lavage, activated charcoal, methylene blue and exchange transfusion should be used. We experienced a case of acute massive Pendipronil(R) intoxication in 31 years old woman due to voluntary ingestion of 48g of this drug as a suicide attempt. A moderate methemoglobinemia developed, accompanied by drowsy mental status, nausea, vomiting, headache, intensive cyanosis. The patient recovered completely after intravenous methylene blue injection and cellulose coated hemoperfusion charcoal (Adsorba 300C(R)) and conservative treatment.

Propanil poisoning.

OBJECTIVE: To document clinical features of propanil poisoning and discuss treatment. DESIGN, SETTING AND PATIENTS: Five patients treated in the University medical unit at the Karapitiya teaching hospital over the past two years. INTERVENTIONS AND MEASUREMENTS: Relevant laboratory investigations were done. The patients were treated on accepted lines. RESULTS: All had methaemoglobinaemia. The first patient died after severe poisoning in spite of intensive treatment. The second had severe poisoning requiring exchange transfusion and treatment with methylene blue. The third, fourth and fifth patients had mild poisoning which responded readily to oral methylene blue. The last patient had taken a combination of propanil and oxydiazone. The first and second patients had features of haemolysis and the second patient had acute hepatitis. CONCLUSIONS: Propanil poisoning is uncommon. Lower levels of methaemoglobin than were previously thought may be associated with a fetal outcome. Methylene blue is used in the treatment as it reduces blood methaemoglobin but in severe poisoning exchange transfusion may be necessary as a life saving measure.