The use of glycopyrrolate in a case of intermediate syndrome following acute organophosphate poisoning

Suspected intermediate syndrome in a dog after organophosphate poisoning

OBJECTIVE

To discuss the clinical presentation and successful treatment of a suspected case of intermediate syndrome due to organophosphate (OP) poisoning in a dog.

CASE SUMMARY

Two dogs presented with acute cholinergic signs after ingesting an OP insecticide containing 50% acephate. Clinical signs consistent with acute cholinergic crisis resolved in both dogs within 24 hours postingestion. One dog developed an onset of neurological signs consistent with intermediate syndrome approximately 24 hours postingestion. This patient's clinical signs resolved with the use of pralidoxime chloride.

NEW OR UNIQUE INFORMATION PROVIDED

OP poisoning most commonly presents as an acute cholinergic crisis, with rare instances of animals developing intermediate syndrome. Few reports of successful treatment and recovery from intermediate syndrome exist in the veterinary literature, particularly with instances in which 2 dogs within the same exposure setting were treated for acute cholinergic signs and only 1 progressed to an intermediate syndrome. This report also highlights the importance of early intervention with pralidoxime chloride prior to the onset of aging.

Factors associated with outcomes in organophosphate and carbamate poisoning: a retrospective study

Organophosphate and carbamate (OPC) poisoning is a major global health hazard requiring immediate medical intervention. Atropine (ATR) is an essential antidote in organophosphate and carbamate poisoning, with the inclusion of cholinesterase reactivators and other anticholinergics, namely pralidoxime (PAM) and glycopyrrolate (GPR). This study aimed to compare the efficacy of various treatment regimens and identify the factors affecting mortality. The data of patients presented at the emergency unit with the consumption of OPC compounds between the years 2013 and 2017 were retrospectively reviewed. The study population was then categorized into four treatment patterns (1) ATR alone, (2) ATR and PAM, (3) ATR and GPR, (4) ATR, PAM and GPR. The outcome of the patients was assessed in terms of survival, intubation, ICU days, and days of ventilation and hospitalization. Univariate and multivariate analyses were performed to investigate the risk factors associated with mortality and odds ratio (OR). A total of 441 patients were included in the study, of which 69.16% were males, and 375 patients survived. Consumption of poison with a suicidal intention was reported in 98.19% of the patients, and the treatment with ATR and PAM (42.86%) was observed to have lower days of ventilation in comparison to the treatment with ATR and GPR (p = 0.003). Patients requiring intubation were also lowest in the group treated with ATR and PAM (27.51%). The age group of > 50 years (OR 4.275 [CI 2.179-8.387]), male gender (OR 2.608 [CI 1.258-5.406]), and the treatment pattern with ATR, PAM and GPR (OR 2.233 [CI 1.002-4.040]) were independently associated with mortality. In summary, male gender, elderly population, and treatment patterns followed adversely affected the outcome in patients with OPC poisoning.

COPD and asthma therapeutics for supportive treatment in organophosphate poisoning

Context: Nerve agents like sarin or VX have repeatedly been used in military conflicts or homicidal attacks, as seen in Syria or Malaysia 2017. Together with pesticides, nerve agents assort as organophosphorus compounds (OP), which inhibit the enzyme acetylcholinesterase. To counteract subsequent fatal symptoms due to acetylcholine (ACh) accumulation, oximes plus atropine are administered, a regimen that lacks efficacy in several cases of OP poisoning. New therapeutics are in development, but still need evaluation before clinical employment. Supportive treatment with already approved drugs presents an alternative, whereby compounds from COPD and asthma therapy are likely options. A recent pilot study by Chowdhury et al. included β2-agonist salbutamol in the treatment of OP-pesticide poisoned patients, yielding ambiguous results concerning the addition. Here, we provide experimental data for further investigations regarding the value of these drugs in OP poisoning. Methods: By video-microscopy, changes in airway area were analyzed in VX-poisoned rat precision cut lung slices (PCLS) after ACh-induced airway contraction and subsequent application of selected anticholinergics/β2-agonists. Results: Glycopyrrolate and ipratropium efficiently antagonized an ACh-induced airway contraction in VX-poisoned PCLS (EC₅₀ glycopyrrolate 15.8 nmol/L, EC₅₀ ipratropium 2.3 nmol/L). β2-agonists formoterol and salbutamol had only negligible effects when solely applied in the same setting. However, combination of formoterol or salbutamol with low dosed glycopyrrolate or atropine led to an additive effect compared to the sole application [50.6 ± 8.8% airway area increase after 10 nmol/L formoterol +1 nmol/L atropine versus 11.7 ± 9.2% (10 nmol/L formoterol) or 8.6 ± 5.9% (1 nmol/L atropine)]. Discussion: We showed antagonizing effects of anticholinergics and β2-agonists on ACh-induced airway contractions in VX-poisoned PCLS, thus providing experimental data to support a prospective comprehensive clinical study. Conclusions: Our results indicate that COPD and asthma therapeutics could be a valuable addition to the treatment of OP poisoning.

A primer on nerve agents: what the emergency responder, anesthesiologist, and intensivist needs to know

PURPOSE

The purpose of this review article is to familiarize first responders, anesthesiologists, and intensivists with the medical management of patients exposed to nerve agents.

SOURCE

This review is based on the current medical literature available to the general medical community.

PRINCIPAL FINDINGS

Nerve agents are some of the deadliest substances known to humanity. Though they kill primarily via muscle paralysis, which leads to respiratory arrest, these agents affect virtually every organ system in the body. Their primary mechanism of action is the body-wide inhibition of cholinesterases. This inhibition leads to the accumulation of acetylcholine, stimulating both nicotinic and muscarinic receptors. After decontamination, the primary treatment is with atropine to control muscarinic symptoms and with oximes to reactivate the cholinesterases and treat the nicotinic symptoms. Atropine doses can be much higher than conventionally used. Seizures are generally best treated with benzodiazepines. Patients with substantial exposure may require ventilatory and intensive care unit support for prolonged periods of time.

CONCLUSION

While it is unlikely that most medical practitioners will ever encounter nerve agent poisoning, it is critical to be aware of the presenting symptoms and how best to treat patients exposed to these deadly agents. History has shown that rapid medical treatment can easily mean the difference between life and death for a patient in this situation.

Essential Lessons in a Potential Sarin Attack Disaster Plan for a Resource-Constrained Environment

Sarin is a potent nerve agent chemical weapon that was originally designed for military purposes as a fast-acting anti-personnel weapon that would kill or disable large numbers of enemy troops. Its potent toxicity, ease of deployment, and rapid degradation allow for rapid deployment by an attacking force, who can safely enter the area of deployment a short while after its release. Sarin has been produced and stockpiled by a number of countries, and large quantities of it still exist despite collective agreements to cease manufacture and destroy stockpiles. Sarin's ease of synthesis, which is easily disseminated across the Internet, increases the risk that terrorist organizations may use sarin to attack civilians. Sarin has been used in a number of terrorist attacks in Japan, and more recently in attacks in the Middle East, where nonmilitary organizations have led much of the disaster relief and provision of medical care. In the present article, we examine and discuss the available literature on sarin's historical use, delivery methods, chemical properties, mechanism of action, decontamination process, and treatment. We present a management guideline to assist with the recognition of an attack and management of victims by medical professionals and disaster relief organizations, specifically in resource-constrained and austere environments. (Disaster Med Public Health Preparedness. 2018;12:249-256).

Gestational Hypertension and Organophosphorus Pesticide Exposure: A Cross-Sectional Study

Hypertension is the most common medical problem encountered during pregnancy, complicating 2-3% of pregnancies. High blood pressure (BP) with diastolic BP ≥ 90 mm Hg and/or systolic BP ≥ 140 mm Hg arising after week 22 of pregnancy and resolving after delivery is defined as gestational hypertension (GHY). The aim of this cross-sectional study was to investigate whether occupational and/or environmental exposure to organophosphorus (OP) pesticide affects GHY. Women at approximately 22 weeks of gestation were recruited. OP pesticide exposure in the first trimester of pregnancy was classified into four categories: no exposure, indirect exposure, domestic exposure, and occupational exposure. Application of the exclusion criteria left 2203 participants (mean age 30.4 ± 11.6 years). Data analysis showed that in women with indirect OP pesticide exposure the incidence of GHY was slightly higher than that in the world population, whereas domestic exposure involved a 7% increase and occupational exposure a 12% increase. Analysis of the pesticides used by participants highlighted a possible role for malathion and diazinon (adjusted OR 1.09 and 1.14, resp.). Further investigation of exposed workers and the general population is clearly warranted given the broad diffusion of OP pesticides and their possible public health impact, maybe by including a wider range of health outcomes.

An atropine and glycopyrrolate combination reduces mortality in organophosphate poisoning

Anticholinergics are the mainstay of the pharmacological management of organophosphate poisoning (OPP). Atropine has the potential to cause central toxicity which may complicate the management of this life-threatening condition. A combination of atropine and glycopyrrolate in equivalent dosages titrated to the peripheral muscarinic signs, theoretically reduces the central effect of the anticholinergics by 50% and thereby the risk of central toxicity, while it provides effective control of the peripheral manifestations of OPP. This study reports the clinical morbidity and mortality associated with the management of OP with this anticholinergic combination over a 4-year period, 2003 to 2006, at Tygerberg Academic Hospital (TAH). Two of the 53 patients treated for OPP died, with this mortality lower than that previously reported at TAH. Atropine toxicity was evident in 12 (22.5%) patients and responded to a temporary cessation of the combination infusion. The demographic profile, presenting symptoms, duration of stay and complications encountered were similar to previous reports from TAH. Patients treated with the infusion of a combination of atropine and glycopyrrolate had a lower mortality rate compared with earlier reports from the same unit, but the occurrence of atropine toxicity was unchanged despite the hypothesized theoretical advantage.

Adjuncts and Alternatives to Oxime Therapy in Organophosphate Poisoning—is There Evidence of Benefit in Human Poisoning? A Review

Organophosphate poisoning is common in developing countries. The morbidity and mortality with organophosphate poisoning is relatively high despite the use of atropine as specific antidotal therapy and oximes to reactivate acetylcholinesterase. Several adjunct and alternative therapies have been explored in animal and human studies. We reviewed the literature to ascertain if there was evidence of benefit of such therapies. Adjunct and alternative therapies included treatments to reduce poison absorption by topical application of creams, enhance toxin elimination by haemoperfusion or bioremediation and neutralise the poison by scavenging free organophosphate with cholinesterase-rich human plasma. In addition, magnesium, clonidine, diazepam, N-acetyl cysteine and adenosine receptor agonists have also been used to counteract poison effects. Detailed assessment was limited by the paucity of trials on adjunct/alternative therapies. The limited evidence from the review process suggested potential benefit from the use of human plasma infusion, early initiation of haemoperfusion and intravenous magnesium, in addition to standard therapy with atropine and pralidoxime. There appeared to be no additional benefit with alkalinisation or use of glycopyrrolate instead of atropine in human trials. Diazepam administration has been advocated by military authorities if symptoms developed following exposure to organophosphate. Bioremediation, clonidine, N-acetyl cysteine and adenosine receptor agonists have been evaluated only in animal models. The impact of adjunct and alternate therapies on outcomes in human poisoning needs to be further explored before implementation as standard treatment.

Early death due to severe organophosphate poisoning is a centrally mediated process

OBJECTIVE

To distinguish whether early death from severe organophosphate (OP) poisoning with dichlorvos is mediated through peripheral or central nervous system (CNS) actions.

METHODS

Wistar rats (n = 72) were randomized to pretreatment with either: normal saline (controls), peripheral anticholinergics (glycopyrrolate [low, medium, or high dose] or nebulized ipratropium bromide), or CNS + peripherally acting anticholinergics (diphenhydramine, nebulized atropine, or injected atropine). All treatments were given prior to a subcutaneous injection of 25 mg/kg dichlorvos (n = 8 per group). Survival was assessed at 10 minutes (early death) and 24 hours (delayed death). Kaplan-Meier (95% confidence intervals [95% CIs]) and chi-squared analysis was then performed to determine differences between treatments.

RESULTS

Regardless of treatment, all animals exhibited profound nicotinic effects (fasciculations) without obvious seizures within 2 minutes of poisoning. In rats pretreated with peripherally acting agents, the fasciculations were rapidly followed by reduced motor activity, sedation, and death. Mortality at 10 minutes for saline controls, glycopyrrolate, and ipratropium was 88%, 96%, and 100%, respectively. The single control animal surviving beyond 10 minutes went on to develop peripheral cholinergic manifestations, including hypersalivation, urination, and defecation. Only one of 24 animals treated with injected atropine, nebulized atropine, or diphenhydramine died during the early phase of poisoning; all others survived to 24 hours (p < 0.01).

CONCLUSIONS

Death in acute, severe OP poisoning is prevented by pretreatment with anticholinergic agents that cross the blood-brain barrier, but not by agents with only peripheral actions. Early death due to OP poisoning appears to be a centrally mediated process.

Intermediate syndrome after malathion ingestion despite continuous infusion of pralidoxime

CASE REPORT

A 33-year-old female ingested an unknown quantity of malathion in a suicide attempt. Cholinergic signs consistent with severe organ, phosphate intoxication developed and were treated within 6 hours of ingestion. Intravenous atropine and a continuous infusion of pralidoxime (400 mg/h) were administered. Prolonged depression of plasma and red blood cell cholinesterases were documented. Despite an initial clinical improvement and the presence of plasma pralidoxime concentrations exceeding 4 microg/mL, the patient developed profound motor paralysis consistent with the diagnosis of Intermediate Syndrome. In addition to the dose and frequency of pralidoxime administration, other factors including persistence of organophosphate in the body, the chemical structure of the ingested organophosphate, and the time elapsed between ingestion and treatment may limit the effectiveness of pralidoxime as an antidote in organophosphate ingestions. This case study suggests that these factors should be taken into account in assessing the risk of Intermediate Syndrome after intentional organophosphate ingestions.

Organophosphorus poisoning and anaesthesia

Organophosphorus compounds, used as insecticides and agents of chemical warfare, are a major global cause of health problems. These irreversible inhibitors of cholinesterase produce three well-recognised clinical entities: the initial cholinergic phase, which is a medical emergency often requiring management in an intensive care unit; the intermediate syndrome, during which prolonged ventilatory care is necessary; and delayed polyneuropathy. In addition, disturbances of body temperature and endocrine function, electrolyte imbalances, immunological dysfunction and disorders of reproduction have been reported in animals and man. Vocal cord paralysis, pancreatitis, cardiac arrhythmias and a wide range of neuropsychiatric disorders are known to follow acute and chronic exposure to organophosphorus compounds. As a result of the inhibition of plasma cholinesterase, there can be increased sensitivity to drugs hydrolysed by this enzyme, e.g. suxamethonium and mivacurium. The inhibition of acetylcholinesterase causes dysfunction at the neuromuscular junction which can produce altered responses to nondepolarizing neuromuscular blockers. Anaesthetists may encounter patients exposed to organophosphorus compounds either following acute poisoning, trauma (warfare) or as patients with a wide range of nonspecific disorders presenting for surgery. The traditional use of oximes and atropine in treatment has failed to reduce the morbidity and mortality associated with poisoning. The roles of agents that have reduced the toxicity of organophosphorus compounds in animal experiments are discussed as potential therapeutic agents. There is an urgent need for accurate information on the problems associated with exposure to organophosphorus compounds. This would best be achieved by collaborative research between technologically advanced countries and developing countries, where organophosphorus compounds are a leading cause of ill health.