Central and autonomic nervous system signs of organophosphate poisoning (OP), such as altered consciousness, noticeable lacrimation, and salivation, can be influenced by medications used in intensive care settings, such as atropine and pralidoxime methyl (PAM). Because of this, there are no established methods for assessing the duration of OP while receiving antidotal treatment. In the present case, we used the Neurological Pupil Index (NPi) to evaluate the duration of OP in an 82-year-old woman who attempted suicide by ingesting up to 100 mL of fenitrothion. Until hospitalization day (HD) 20, discontinuation of atropine led to the recurrence of altered consciousness, while its reinstatement resulted in improvement; this made it difficult to assess the prolongation of OP based on signs and symptoms. Until HD 20, the NPi remained at 0/0, and subsequently, it increased. Additionally, even after discontinuing atropine, consciousness, tearing, and salivation did not worsen, indicating recovery from OP. On HD 26, serum acetylcholinesterase (AChE) levels were elevated above the measurable level for the first time, following an increase in the NPi. In this case, assessing the persistence of OP based on signs was challenging because these signs improved with atropine and PAM treatment. The improvement in NPi levels coincided with an improvement in poisoning, suggesting that NPi is useful for evaluating the duration of OP. NPi is noninvasive and sensitive compared to AChE, which is used to gauge the persistence of OP and could be used to allow earlier cessation of medication and guide appropriate treatment durations.

Organophosphorus (OP) poisoning is the most common type of poisoning in India. Amongst the OP, monocrotophos poisoning has the highest lethality and need for mechanical ventilation. Monocrotophos is also implicated in causing OP-induced intermediate syndrome, the prevalence of which is 10-40% of all OP poisoning. The other neurological manifestations are delayed neuropathy and neuropsychiatric syndrome. We herein discuss a case of a 58-year-old male who presented with monocrotophos poisoning and intermediate syndrome. During the hospitalisation course, the patient developed hyperammonemic encephalopathy, resulting in difficulty in weaning from mechanical ventilation. After ruling out all possible causes of hyperammonemia, it was attributed to monocrotophos poisoning. The patient improved significantly after initiating lactulose and was successfully weaned off from the ventilator. This report highlights the high index of suspicion of hyperammonemic encephalopathy in monocrotophos toxicity, which can be easily missed due to other commoner neurological manifestations of organophosphorus poisoning.

Pesticides have contributed to dramatic increase in the quality and quantity in crop yields. Organophosphates are commonly used as insecticides in agriculture and are potent toxicants. Patients with organophosphorus poisoning may present with subclinical features of acute pancreatitis. Proper biochemical investigation and clinical correlation helps in diagnosis.