Successful treatment of methemoglobinemia in an elderly couple with severe cyanosis: two case reports

INTRODUCTION: Methemoglobinemia should be considered in all cyanotic patients who remain unresponsive to oxygen therapy. Rapid diagnosis is very important in emergency cases. Here, we present the cases of two patients, a married couple, admitted to our hospital with methemoglobinemia after exposure to sodium nitrite. CASE PRESENTATION: Two patients, a married couple, presented with methemoglobinemia. The 72-year-old Taiwanese man and 68-year-old Taiwanese woman were referred to our hospital with dizziness and tachypnea. On examination, their mucous membranes were cyanotic, and their blood samples showed the classic ‘chocolate brown’ appearance. The man also reported having experienced twitching of his right arm for a few minutes before arrival at the hospital. The symptoms of both patients failed to improve in response to supplemental oxygen delivered via oxygen masks, although the arterial blood gas data of these patients were normal and their pulse oximetry showed oxyhemoglobin levels of approximately 85%. A carbon monoxide-oximeter showed that the man’s methemoglobin concentration was 48.3%, and the woman’s was 36.4%. Methylene blue (100mg) was administered intravenously to both patients, and their symptoms improved dramatically. They were admitted to the intensive care unit and discharged three days later, without neurological sequelae. CONCLUSION: Severe methemoglobinemia is a life-threatening condition and, if untreated, may result in death. Early diagnosis and appropriate antidotal treatment are crucial in treating this emergency situation.