A Case Series of Acquired Methemoglobinemia Due to Pesticides: Conventional to Novel Therapies

Abstract

A 57-year-old gentleman with an alleged history of (h/o) consumption of approximately 50-100 mL of a pesticide (1:2 compound, containing bioemulsifier 6%; oligosaccharide, 8%; fillers/carriers, 86%) at his home presented within 2 hours to a private hospital where gastric lavage was done and referred for deteriorating conscious level. On arrival, 5 hours from the time of consumption, he was stuporous. Glasgow Coma Scale (GCS) was 7/15, had central cyanosis, SpO 2 -62% with severe hypotension, which responded to fluid. In view of poor GCS and low SpO 2 , he was ventilated. Post intubation SpO 2 -86% with 100% FiO 2 . His blood gas revealed normal saturations, and co-oximetry showed a methemoglobin level of 63.5%. In view of raised MetHb, he was administered 2 mg/kg of methylene blue and shifted to ICU. In the subsequent arterial blood gas, methemoglobin levels remained high. Further boluses of methylene blue were tried upto a cumulative dose of 7 mg/kg without consistent reduction of methemoglobin levels to normalcy. Glucose-6-phosphate dehydrogenase (G6PD) deficiency was ruled out. A hematologist consultation was obtained, and one cycle of plasmapheresis was attempted, but the level did not decrease. An exchange