A 21yr old male presented to an emergency room from a peripheral hospital with an alleged history of consumption of unknown quantity of insecticide ‘PLETHORA’ (5.25%NOVALU RON+4.5%INDOXACARB4.5% W/V).History revealed that he was conscious, coherent, with good muscle power and normal pupils, in a stable hemodynamical condition but with a saturation of 85%on room air. So he was started on NIV support.
Meanwhile, the patient developed peripheral cyanosis and shifted to our hospital for further management (time frame-20hrs after consumption of poison). In the ER, a general examination was unremarkable. The patient was mildly hypotensive and hypoxic with a saturation of less than 80% on 10lts o2 NRBM. ABG was hypoxemic, hence pt. was intubated and mechanically ventilated in assist VCV with 100% Fio2.
There was no improvement in saturation. His chest x-ray and 2D echo were unremarkable. Pseudocholine esterase levels were normal. As his saturation was not improving with ventilation, with a normal chest x-ray and brown coloured blood samples gave a suspicion of histotoxic hypoxia.
Further, the literature reviewed suggested a compound of poison INDOXACARB has potential to cause methemoglobinemia. So ABG oximetry was sent and it revealed saturation gap and meth-HB levels of 43%. (FIG 1A,1B). G6PD levels were sent and it was normal. So, given a loading dose of methylene blue (2mg/kg/over an hour) and saturations improved to 100% with the same ventilator support. Repeat co-oximetry revealed meth-Hb of 1.6% (FIG 2A,2B).In view of rebound, phenomenon patient was given a maintenance dose of inj.methylene blue at 1mg/kg/over 12hrs. During this 12hrs Fio2 was reduced to 50% while maintaining saturation of 99%.
Repeat co-oximetry after 12hrs of maintenance dose revealed meth-Hb of 0.2%. After successful SBT patient was extubated. repeat co-oximetry after 24hrs of extubation showed meth-HB of 2%. Further course of stay in hospital was uneventful.on day -3 his met-Hb was 1.7%. He was discharged on day 3 with a saturation of 99% on room air, in hemodynamically stable condition.
Dr T Sateesh Kumar, IDCCM, D.A, MBBS, Consultant Critical Care Apollo Hospitals, Secunderabad.
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