Retrospective Observational Study of Organophosphate Poisoning in an Urban Malaysian Hospital

Abstract

Objectives: The objective of this study is to determine treatment interventions that provided the best outcome for patients. Initial treatment interventions performed in the emergency department such as decontamination, antidote administration and intubation will be analysed. Subsequent management in the intensive care unit with complications related to invasive ventilation will be analysed. The risks of aspiration pneumonia for patients who underwent gastric lavage with or without administration of activated charcoal will also be analysed. Methods: A retrospective observational study was conducted. Study population included all patients presenting to the emergency department of Hospital Tengku Ampuan Rahimah with history of having consumed an organophosphate from the 1 st April 2013 to 31 st March 2016. The inclusion criteria was all patients with history of ingesting an insecticide containing a suspected organophosphate. The exclusion criteria was patients confirmed not to have ingested an organophosphate from clinical inference and confirmation of actual poison. Results: A total of 84 patients were sampled with 75 patients fulfilling criteria for study inclusion. A total of 22 cases developed complications during their hospital stay with 13 cases of nosocomial infection, 8 cases of aspiration pneumonia, 2 cases with in hospital cardiac arrest and 1 case of atropine toxicity. Malathion and chlorpyrifos were the only two identified organophosphates with the remaining 38 having consumed an unidentified organophosphate. Using chi-square test, there appears to be a significant difference between chlorpyrifos and malathion in terms of need for intubation with a p value of 0.017. Conclusion: Resuscitation of airway, breathing and circulation with close observation for early signs of proximal muscle weakness or paralysis countered with judicious atropine administration is sufficient to ensure good outcome for cases of malathion and chlorpyrifos poisoning which present early to the emergency department. The risk of aspiration pneumonia is high in patients with organophosphate poisoning outweighing the benefits of performing a gastric lavage. Aspiration of stomach contents with a ryle's tube after endotracheal intubation is an acceptable method of gastrointestinal decontamination for patients who have consumed a large quantity of organophosphate. Pralidoxime may be beneficial in reducing the period of respiratory paralysis or weakness for chlorpyrifos poisoning but shows no clear benefit for malathion poisoning. The prolonged muscle paralysis seen in malathion poisoning weighs heavily on intensive care resources. Banning the sale of malathion may help reduce morbidity from prolonged ventilation as well as reduce the burden on intensive care resources.