A pilot clinical study of the neuromuscular blocker rocuronium to reduce the duration of ventilation after organophosphorus insecticide poisoning

Acute organophosphate and carbamate pesticide poisonings - a five-year survey from the National Poison Control Center Of Serbia

Pesticide poisonings, intentional as well as accidental, are common, especially in undeveloped and developing countries. The goal of this study was to analyze the clinical presentation of patients hospitalized due to acute organophosphate (OPP) or carbamate pesticide (CP) poisoning as well as to analyze the factors that potentially influenced the severity and outcome of the poisonings. A retrospective cross-sectional study was performed. The age and gender of each patient were recorded, the type of ingested pesticide, whether the poisoning was intentional or accidental, number of days of hospitalization, the severity of the poisoning, and the outcome of the treatment (i.e., whether the patient survived or not). Clinical aspects of poisonings were analyzed, as well as the therapeutic measures performed. 60 patients were hospitalized due to acute OPP or CP poisoning, out of 51 (85.00%) were cases of intentional self-poisoning. The majority of patients were poisoned by OPPs (76.67%), in one-third the causative agent was malathion, followed in frequency by chlorpyrifos and diazinon. Dimethoate poisonings were manifested with the most severe clinical picture. A 70% or lower activity of reference values of acetylcholinesterase and butyrylcholinesterase was found in 50% and 58% of patients, respectively. The most common symptom was miosis (58.33%), followed by nausea and vomiting. Pralidoxime reactivated acetylcholinesterase inhibited by chlorpyrifos or diazinon, but not with malathion or dimethoate. Impairment of consciousness and respiratory failure, as well as the degree of acetylcholinesterase and butyrylcholinesterase inhibition, were prognostic signs of the severity of poisoning. The lethal outcome was more often found in older patients (t = 2.41, p = 0.019). The type of ingested pesticide significantly affects the severity and outcome of poisoning as well as the effectiveness of antidotes.

Dose-Dependency of Toxic Signs and Outcomes of Paraoxon Poisoning in Rats

Organophosphorus compounds induce irreversible inhibition of acetylcholinesterase, which then produces clinically manifested muscarinic, nicotinic and central effects. The aim of the study was to analyse the clinical signs of acute paraoxon poisoning in rats and to determine the relationship between the intensity of signs of poisoning and the dose of paraoxon and/or the outcome of poisoning in rats. Animals were treated with either saline or atropine (10 mg/kg intramuscularly). The median subcutaneous lethal dose (LD50) of paraoxon was 0.33 mg/kg and protective ratio of atropine was 2.73. The presence and intensity of signs of poisoning in rats (dyspnoea, lacrimation, exophthalmos, fasciculations, tremor, ataxia, seizures, piloerection, stereotypic movements) were observed and recorded for 4 h after the injection of paraoxon. Intensity of these toxic phenomena was evaluated as: 0 - absent, 1 - mild/moderate, 2 - severe. Fasciculations, seizures and tremor were more intense at higher doses of paraoxon and in non-survivors. In unprotected rats piloerection occurred more often and was more intense at higher doses of paraoxon as well as in non-survivors. In atropine-protected rats, piloerection did not correlate with paraoxon dose or outcome of poisoning. The intensity of fasciculations and seizures were very strong prognostic parameters of the poisoning severity.

Lipid emulsion for the treatment of acute organophosphate poisoning: an Open-Label randomized trial

INTRODUCTION

Many organophosphate (OP) pesticides are lipid-soluble; therefore, intravenous lipid emulsion (ILE) has been evaluated as a possible treatment for acute poisoning. A single bolus dose of 100 ml of 20% ILE was found safe in a pilot observational study. This randomized trial aimed to assess the effectiveness and safety of an extended dose of ILE in acute OP poisoning.

METHODS

This was an investigator-initiated, parallel-group, open-label, randomized controlled trial conducted at PGIMER, Chandigarh (India), from January 2019 to June 2020, in patients aged above 13 years with acute OP poisoning. The primary efficacy outcome was to study the change in atropine dose requirement (total and over the first 24 h) for cholinergic crisis after giving an initial bolus dose of 100 ml of 20% ILE followed by an infusion of 100 ml of 20% ILE over 6 h in addition to the standard care. The secondary efficacy outcomes were to detect the effects on hemodynamic variables, length of hospital stay, and duration of mechanical ventilation required. The incidence of adverse events was evaluated.

RESULTS

A total of 45 patients were assigned to receive either ILE (intervention group, n = 23) or normal saline (control group, n = 22) in addition to standard treatment. Baseline variables in both groups were comparable. The median dose of atropine (in mg) in the first 24 h and at complete resolution in the ILE group were similar to the control group (124.0 versus 141.8, p-value 0.916; and 150.8 versus 175.0, p-value 0.935). Hemodynamic variables (systolic and diastolic blood pressures, mean arterial pressure, and pulse rate) over 24, 48, and 72 h of treatment, length of hospital stay, and duration of mechanical ventilation were also unaffected by ILE. Case fatality was 4 and not statistically different between intervention and control groups (1 versus 3, p-value 0.346). There was no excessive fever, dyspnea, elevation of serum amylase, or pancreatitis from ILE.

CONCLUSION

ILE has no apparent benefit in acute OP poisoning. However, an extended dose appears safe for the indication.

Osmolal and anion gaps after acute self-poisoning with agricultural formulations of the organophosphorus insecticides profenofos and diazinon: A pilot study

Self-poisoning with organophosphorus (OP) insecticides is an important means of global self-harm. The insecticides are formulated with solvents that may also contribute to toxicity. We set up a study to detect changes in osmolal and anion gaps following ingestion of OP insecticides. We recruited consecutive patients admitted to a Teaching Hospital, Sri Lanka, with a history of OP self-poisoning. The osmolal and anion gaps were calculated on admission and at 4, 24 and 72 h post-ingestion together with ethanol concentration. Forty-nine patients were recruited (28 profenofos, 10 diazinon, one coumaphos, one chlorpyrifos, one phenthoate and eight unknown OP). Only modest increases in osmolal and anion gaps were noted. Small rises in osmolal gap above the upper limit of normal were noted in 16/49 (32.7%) of all cases, 9/28 (32.1%) profenofos cases and 4/10 (40.0%) diazinon cases. The anion gap was raised in 24/49 (49.0%) of all cases, 15/28 (53.6%) profenofos cases and 5/10 (50.0%) diazinon cases. We observed a trend for a fall in osmolal gap during the first 24 h, followed by an increase up to 72 h. There was no correlation between the anion gap and serum lactate concentration, indicating that a lactic acidosis was not responsible for the anion gap. Formate, which could have explained the increased gap, was not detected in any of the samples; ketoacids (beta-hydroxybutyrate and acetoacetate) were not measured. This pilot study found that profenofos and diazinon poisoning caused only modest increases in the osmolal and anion gaps in a minority of cases.

Management of Organophosphorus Poisoning: Standard Treatment and Beyond

Organophosphorus (OP) compounds remain a leading cause of self-poisoning and mortality, especially in South East Asia, China, and Africa. Organophosphorus causes an acute cholinergic syndrome by inhibiting acetylcholinesterase. Atropine remains the mainstay of treatment, but recently some promising therapies are in the pipeline. Oximes are used widely in the management of organophosphorus poisoning, however clinical efficacy remains to be established. Magnesium sulfate, calcium channel blockers (nimodipine), plasma alkalinizing agents, β-2 agonists, nicotinic receptor antagonists, clonidine, and lipid emulsions are promising treatment alternatives. However, large phase III trials are required to establish their efficacy.

Onset rate and intensity of signs of organophosphate poisoning related to paraoxon dose and survival in rats

Introduction: Oganophosphorus compounds (OP) bind to acetylcholinesterase (AChE) and inactivate it. In the synaptic cleft, undestroyed and accumulated acetylcholine produce the acute cholinergic effects. The aim of this study was to determine the frequency, speed of onset and intensity of certain signs of paraoxon poisoning depending on dose and outcome of poisoning. Methods: The study was conducted in adult Wistar rats. The median lethal dose (LD50) of paraoxon as well as protective ratio (PR) of atropine (10 mg/kg intramuscularly) was determined. Clinical signs of poisoning were observed: fasciculations, tremor, seizures, ataxia, piloerection, lacrimation, exophthalmos, bizzare/stereotypic behaviour and dyspnoea. The time from paraoxon injection to the first appearance of the sign of poisoning was recorded as well as the intensity of poisoning with evaluation at 10 time intervals throughout the 4 h observational period. Results: The LD50 of paraoxon was 0.33 mg/kg (subcutaneously) and PR of atropine was 2.73. Dose-dependent, piloerection occurred more often (p = 0.009) and at higher intensity (p = 0.016) at higher doses. Fasciculations, tremor, seizures and ataxia occurred significantly earlier at higher doses of paraoxon (p = 0.015, 0.002, 0.021 and 0.016, respectively), as well as the intensity of seizure, tremor and fasciculation. Piloerection (p = 0.002) and seizures occurred more frequently (p = 0.009) in non-survivors. Fasciculations, tremor, seizures and ataxia occurred significantly earlier and at higher intensity in non-survivors (p < 0.001, for all parameters), as well as dyspnoea (p = 0.009 and p = 0.048). In atropine-protected rats, nicotinic effects persevered, so they were the prognostic parameter of the severity of the poisoning. Conclusion: Seizures and fasciculations followed by tremor were strong prognostic parameters of the probability of lethal outcome of paraoxon poisoning. Also, the mentioned poisoning signs were with their intensity and speed of occurrence in a clear positive correlation with the administered dose of paraoxon. Even at high doses of paraoxon, atropine blocked the muscarinic (but not nicotinic) effects and somewhat mitigated the CNS toxic effects.