Hypotension in severe dimethoate self-poisoning

Abstract

Introduction. Acute self-poisoning with the organophosphorus (OP) pesticide dimethoate has a human case fatality three-fold higher than poisoning with chlorpyrifos despite similar animal toxicity. The typical clinical presentation of severe dimethoate poisoning is quite distinct from that of chlorpyrifos and other OP pesticides: many patients present with hypotension that progresses to shock and death within 12-48 h post-ingestion. The pathophysiology of this syndrome is not clear. Case reports. We present here three patients with proven severe dimethoate poisoning. Clinically, all had inappropriate peripheral vasodilatation and profound hypotension on presentation, which progressed despite treatment with atropine, i.v. fluids, pralidoxime chloride, and inotropes. All died 2.5-32 h post-admission. Continuous cardiac monitoring and quantification of troponin T provided little evidence for a primary cardiotoxic effect of dimethoate. Conclusion. Severe dimethoate self-poisoning causes a syndrome characterized by marked hypotension with progression to distributive shock and death despite standard treatments. A lack of cardiotoxicity until just before death suggests that the mechanism is of OP-induced low systemic vascular resistance (SVR). Further invasive studies of cardiac function and SVR, and post-mortem histology, are required to better describe this syndrome and to establish the role of vasopressors and high-dose atropine in therapy.

Applied clinical pharmacology and public health in rural Asia – preventing deaths from organophosphorus pesticide and yellow oleander poisoning

“…Dimethoate EC40 2.5 ml kg –1 (containing 1.0 g kg –1 dimethoate AI) caused severe toxicity, with early respiratory arrest and cardiovascular collapse that could be transiently treated with very large doses of norepinephrine. The pattern of poisoning was very similar to that of human poisoning , including a complete lack of effect of pralidoxime . A lower dose of dimethoate EC40 (1.25 ml kg –1 ) produced only modest toxicity.…”

“…The pure insecticide, the ‘active ingredient’ (AI), is not by itself usable. To explore their role, we established a Gottingen minipig model of agricultural dimethoate poisoning, using the standard 40% emulsifiable concentrate formulation (dimethoate EC40) that is ingested by humans . The preparation contains 40% dimethoate, 40% cyclohexanone, 5% xylene and a surfactant called Wettol (since the surfactant is considered non‐toxic, the company does not declare its concentration in the preparation).…”

Stakeholder engagement in social learning to resolve controversies over land-use change to plantation forestry

“…The high water solubility of dimethoate (Johnson et al 2007) when applied under a sub-tropical rainfall pattern provides argument for significant dilution of this pesticide in the environment that should not present significant health risks at rates and frequencies (Margni et al 2002) used by the plantation forestry industry. However due to the nature of organophosphorus pesticides for acute toxicity, it should be used with caution and further toxicology investigations undertaken (Davies et al 2008;Eddleston et al 2005).…”

Organophosphorus Pesticides

“…Among 802 patients with chlorpyrifos, dimethoate, or fenthion poisoning, dimethoate had the highest fatality rate (23%) and dimethoate poisoned patients died sooner than those ingesting chlorpyrifos of fenthion, often from hypotensive shock (369,370).…”