Amitraz: an unusual aetiology of Ogilvie's syndrome

Acute Colonic Pseudo-Obstruction Following the Use of Dexmedetomidine

Dexmedetomidine is a preferred agent for light sedation with minimal adverse effects. We report a case of acute colonic pseudo-obstruction following dexmedetomidine use in a patient with alcohol withdrawal. He was treated with benzodiazepines first to control the withdrawal symptoms, then escalated to dexmedetomidine once delirium tremens ensued. Later on, the patient developed abdominal distension and vomiting. Imaging showed dilated bowel loops and absence of peristalsis on ultrasound. Decompression with the nasogastric (NG) tube was done, with high output from the NG tube. Dexmedetomidine infusion was used twice, and once it was stopped, the NG tube output was reduced, with the resumption of gastrointestinal motility and improvement of the abdominal distension. Recent similar reports of functional intestinal obstruction following alpha-2 (α2) agonist use necessitate further studies of intestinal motility following dexmedetomidine use and awareness of the possible side effect of dexmedetomidine on intestinal motility.

Intoxicación por amitraz. Un reporte de caso

El amitraz es un compuesto insecticida utilizado a nivel mundial para el control de plagas, en especial en áreas rurales agrícolas y ganaderas. La intoxicación por amitraz es infrecuente en Colombia. Se presenta el caso de una paciente de 18 años de edad, quien ingresa al servicio de urgencias 3 horas después de la ingesta de Triatox® (amitraz) en cantidad desconocida. La mujer llega con depresión del estado de conciencia, dificultad respiratoria, hipotensión, bradicardia, miosis y acidosis metabólica compensada con alcalosis respiratoria, por lo que se le suministra tratamiento inicial con medidas de soporte vital en el servicio de urgencias, con posterior necesidad de traslado y soporte en la unidad de cuidados intensivos, siendo dada de alta de la misma unidad 24 horas después del ingreso. El caso pone en consideración la similitud clínica entre la intoxicación por amitraz y la debida a otros compuestos tóxicos más frecuentes como carbamatos, organofosforados y opioides, los cuales requieren un manejo distinto.

Acute colonic pseudo-obstruction: A systematic review of aetiology and mechanisms

AIM

To critically review the literature addressing the definition, epidemiology, aetiology and pathophysiology of acute colonic pseudo-obstruction (ACPO).

METHODS

A systematic search was performed to identify articles investigating the aetiology and pathophysiology of ACPO. A narrative synthesis of the evidence was undertaken.

RESULTS

No consistent approach to the definition or reporting of ACPO has been developed, which has led to overlapping investigation with other conditions. A vast array of risk factors has been identified, supporting a multifactorial aetiology. The pathophysiological mechanisms remain unclear, but are likely related to altered autonomic regulation of colonic motility, in the setting of other predisposing factors.

CONCLUSION

Future research should aim to establish a clear and consistent definition of ACPO, and elucidate the pathophysiological mechanisms leading to altered colonic function. An improved understanding of the aetiology of ACPO may facilitate the development of targeted strategies for its prevention and treatment.

Amitraz, an underrecognized poison: A systematic review

Background & objectives:

Amitraz is a member of formamidine family of pesticides. Poisoning from amitraz is underrecognized even in areas where it is widely available. It is frequently misdiagnosed as organophosphate poisoning. This systematic review provides information on the epidemiology, toxicokinetics, mechanisms of toxicity, clinical features, diagnosis and management of amitraz poisoning.

Methods:

Medline and Embase databases were searched systematically (since inception to January 2014) for case reports, case series and original articles using the following search terms: ‘amitraz’, ‘poisoning’, ‘toxicity’, ‘intoxication’ and ‘overdose’. Articles published in a language other than English, abstracts and those not providing sufficient clinical information were excluded.

Results:

The original search yielded 239 articles, of which 52 articles described human cases. After following the inclusion and exclusion criteria, 32 studies describing 310 cases (151 females, 175 children) of human poisoning with amitraz were included in this systematic review. The most commonly reported clinical features of amitraz poisoning were altered sensorium, miosis, hyperglycaemia, bradycardia, vomiting, respiratory failure, hypotension and hypothermia. Amitraz poisoning carried a good prognosis with only six reported deaths (case fatality rate, 1.9%). Nearly 20 and 11.9 per cent of the patients required mechanical ventilation and inotropic support, respectively. The role of decontamination methods, namely, gastric lavage and activated charcoal was unclear.

Interpretation & conclusions:

Our review shows that amitraz is an important agent for accidental or suicidal poisoning in both adults and children. It has a good prognosis with supportive management.

Amitraz poisoning: A case report of an unusual pesticide poisoning in Sri Lanka and literature review

Background

Amitraz is a pesticide used worldwide on animals and in agriculture. It contains triazapentadiene, which is a centrally acting alpha-2 adrenergic agonist. Amitraz poisoning is fairly uncommon in humans and occurs via oral, dermal or inhalational routes. Only a limited number of case reports of human intoxication have been published and most of them are of accidental ingestion by children.

Case presentation

A twenty-year-old Sri Lankan female presented following self-ingestion of 20 ml of amitraz resulting in 37.8 mg/ kg of amitraz poisoning. She lost consciousness after 20 min of ingestion, developed bradycardia and hypotension, which needed intravenous fluid resuscitation and dobutamine. Gastric lavage was performed. Her bradycardia persisted for 36 h and she was drowsy for 48 h. She did not develop respiratory depression, convulsions or hypothermia and the urine output was normal. Arterial blood gas revealed mild respiratory alkalosis. She recovered fully within 48 h and was discharged on day 3.

Conclusion

The clinical manifestations of amitraz (impaired consciousness, drowsiness, vomiting, disorientation, miosis, mydriasis, hypotension, bradycardia, respiratory depression, hypothermia, generalized seizures, hyperglycemia and glycosuria) can be explained by the agonist action of amitraz on α1 and α2 receptors. Management of amitraz poisoning is still considered to be supportive and symptomatic with monitoring of nervous system, cardiovascular and respiratory systems. Activated charcoal may still be considered for treatment and the place for gastric lavage is controversial. Atropine is effective for symptomatic bradycardia and inotropic support is needed for hypotension that does not respond to fluid resuscitation. Diazepam or Lorazepam is used for convulsions and some patients may require intubation and ICU care. Several α2 adrenergic antagonists like yohimbine have been tried on animals, which have successfully reversed the effects of amitraz. Since the majority of amitraz poisoning cases are due to accidental ingestion, manufactures, regulatory authorities and national poisons control centers have a significant role to play in minimizing its occurrence.

Amitraz poisoning in South Africa: a two year survey (2008-2009)

INTRODUCTION

Analysis of the annual pesticide poisoning statistics of the Tygerberg Poison Information Centre (TPIC) for the period 2005-2007 showed an increase in the number of amitraz poisonings. This prompted a 2-year survey (2008-2009) to establish the extent of amitraz poisoning in South Africa. Amitraz is a pesticide used as a tick dip. It acts as an α(2)-adrenoceptor agonist and the principal clinical effects of amitraz poisoning are related to its stimulation of these receptors;

METHODS

Data from amitraz poisoning cases in humans were evaluated for 2 years and analyzed for: demographic data, type of exposure, type of formulation, and clinical details. Serious cases were followed up;

RESULTS

4.6% of the pesticide poisoning cases were amitraz-related which comprised 0.8% of all TPIC poisoning consultations. Ingestion of amitraz formulations accounted for the majority of the cases (94%). Forty-one percent of cases were children (n = 28) and all were accidental exposures. Of the adult cases (59%), 88% were intentional ingestions. The majority of the cases were from the predominantly rural province of KwaZulu Natal (44.9%). CNS depression was the most common clinical sign (76.8%) followed by bradycardia 34.8%, respiratory depression 27.5%, miosis 27.5%, and hypotension 23.1%. Mechanical ventilation was required in 15.9% of cases. Other commonly reported clinical signs were hypothermia 15.9%, mydriasis 10.1%, and hyperglycaemia 7.2%. Supportive and symptomatic care was shown to be adequate treatment. Amitraz poisoning was misdiagnosed as cholinesterase inhibitor poisoning in 17.4% of cases;

CONCLUSION

This is the first report of amitraz poisoning in humans in Africa. The data suggest a different demographic pattern in South Africa to that currently reported in the literature. The study identified a very high incidence of intentional poisoning in adults. The misuse of amitraz for deliberate self-harm emphasizes the necessity for continued toxicovigilance.