pralidoxime and Hypotension

Amitraz is used as an ectoparasiticide for dogs and cattle. Human poisoning due to amitraz may be misdiagnosed as organophosphate/carbamate (OPC) toxicity, since amitraz poisoning shares several clinical features (miosis, bradycardia and hypotension) encountered with OPC poisoning. A 19-year-old man with an alleged history of suicidal ingestion of a pesticide presented with drowsiness and was found to have constricted pupils, hypotension and bradycardia. He was diagnosed as a case of OPC poisoning and was treated with atropine and pralidoxime prior to presentation to our centre. Absence of a hypersecretory state, and the presence of hyperglycaemia and hypothermia along with a normal serum cholinesterase level suggested an alternate possibility. Retrieval of the poison container confirmed the diagnosis of amitraz poisoning. The patient made a rapid recovery with supportive management. Clinician awareness is key to successful management of this poisoning, which carries a good prognosis.

Topics: Atropine; Bradycardia; Cholinesterase Reactivators; Diagnosis, Differential; Diagnostic Errors; Follow-Up Studies; Humans; Hyperglycemia; Hypotension; Male; Miosis; Organophosphate Poisoning; Parasympatholytics; Pralidoxime Compounds; Suicide, Attempted; Toluidines; Treatment Outcome; Young Adult

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.. 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.. 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.

Topics: Antidotes; Atropine; Cardiotonic Agents; Dimethoate; Humans; Hypotension; Insecticides; Male; Middle Aged; Pralidoxime Compounds; Suicide; Vasodilation

Topics: Acetylcholine; Blood Pressure; Blood Pressure Determination; Chloralose; Cholinesterases; Dogs; Hypertension; Hypotension; Oximes; Pharmacology; Phosphates; Pralidoxime Compounds; Pyridines; Research