Organophosphate poisoning: peripheral vascular resistance--a measure of adequate atropinization

Clinical characteristics and early prediction of mortality risk in patients with acute organophosphate poisoning-induced shock

Objective

To further get insights of clinical characteristics of acute organophosphate poisoning-induced shock, investigate the relationship between shock and prognosis, and screen risk indicators for prognosis.

Methods

A total of 73 patients with acute organophosphate poisoning admitted to our hospital between January 2014 and December 2021 were enrolled in this retrospective study. Patients were divided into the shock group and the non-shock group. The pH value of blood, arterial blood carbon dioxide partial pressure (PaCO₂), arterial partial pressure of oxygen (PaO₂), base excess (BE), lactic acid (Lac), serum albumin (ALB), total bilirubin (TBIL), alanine aminotransferase (ALT), serum creatinine (Cr), serum potassium (K), serum calcium (Ca), serum sodium (Na), blood chloride (Cl), serum troponin I (cTNI), brain natriuretic peptide (BNP), white blood cell count (WBC), hemoglobin (HGB), platelet count (PLT), and other clinical indicators of patients were recorded. Incidence of shock, time of shock onset, and outcomes of patients were also recorded. Cox proportional hazards regression models were performed for analysis.

Results

The incidence of organophosphate poisoning-induced shock was 30.1% (22/73), and 72.7% of shock patients developed shock blood pressure within 6 h. The levels of blood lactate, ALT, Cr, cTNI, BNP, and Cl in the shock group were significantly higher than those in the non-shock group, while the level of Ca and pH value was significantly lower than that in the non-shock group (all p < 0.05). Moreover, compared with patients without shock (2.0%), the mortality rate was significantly increased in patients with shock (36.4%), which was supported by the results from adjusted Cox proportional hazards regression model. We found that shock and elevated serum creatinine were associated with increased risk of death in patients with organophosphate poisoning (shock: HR, 10.9; 95% CI 1.2-96.3; elevated serum creatinine: HR, 1.0, 95% CI 1.0-1.0).

Conclusion

This study indicated the association between elevated serum creatinine and increased mortality rates in patients with organophosphate poisoning, highlighting the importance of the comprehensive management of shock, especially the control of renal function, in these poisoning patients.

Outcomes of elderly patients with organophosphate intoxication

This study analysed the clinical patterns and outcomes of elderly patients with organophosphate intoxication. A total of 71 elderly patients with organophosphate poisoning were seen between 2008 and 2017. Patients were stratified into two subgroups: survivors (n = 57) or nonsurvivors (n = 14). Chlorpyrifos accounted for 33.8% of the cases, followed by methamidophos (12.7%) and mevinphos (11.3%). Mood, adjustment and psychotic disorder were noted in 39.4%, 33.8% and 2.8% of patients, respectively. All patients were treated with atropine and pralidoxime therapies. Acute cholinergic crisis developed in all cases (100.0%). The complications included respiratory failure (52.1%), aspiration pneumonia (50.7%), acute kidney injury (43.7%), severe consciousness disturbance (25.4%), shock (14.1%) and seizures (4.2%). Some patients also developed intermediate syndrome (15.5%) and delayed neuropathy (4.2%). The nonsurvivors suffered higher rates of hypotension (P < 0.001), shock (P < 0.001) and kidney injury (P = 0.001) than survivors did. Kaplan–Meier analysis indicated that patients with shock suffered lower cumulative survival than did patients without shock (log-rank test, P < 0.001). In a multivariate-Cox-regression model, shock was a significant predictor of mortality after intoxication (odds ratio 18.182, 95% confidence interval 2.045–166.667, P = 0.009). The mortality rate was 19.7%. Acute cholinergic crisis, intermediate syndrome, and delayed neuropathy developed in 100.0%, 15.5%, and 4.2% of patients, respectively.

Dichlorvos Poisoning: A Mystery Case of Distributive Shock Unraveling with Atropine

Hypotension can be explained by the cardiotoxic effects of an organophosphate poison, but a distributive shock is a rare event. This is a case report of a young north Indian man who presented to the emergency room in a comatose state and distributive shock. He was initially managed with intravenous crystalloids but required inotropic therapy to maintain the desired mean arterial pressure and organ perfusion and also required mechanical ventilation. He improved during the hospital stay only after 4 days when cocktail treatment of atropine was started considering the possibility of organophosphorus toxin exposure and had tapered off the inotropes and mechanical ventilation. Dichlorvos ingestion was confirmed later on after recovery from the coma. At 4-week follow-up, he developed delayed neuropathy. This case is a torchlight toward organophosphorus poisoning presenting as a distributive shock. Atropine may be used as a cocktail treatment in distributive shock where the diagnosis is uncertain. How to cite this article: Suresh S, Panda PK. Dichlorvos Poisoning: A Mystery Case of Distributive Shock Unraveling with Atropine. Indian J Crit Care Med 2021;25(3):337-339.

Clinical correlates of hypotension in patients with acute organophosphorus poisoning

BACKGROUND

The aim of the present study is to describe the clinical correlates of hypotension and its associated outcomes in patients with acute organophosphorus poisoning (AOPP).

METHODS

In this retrospective cohort study, we analyzed data pertaining to 871 patients with AOPP who were treated at two hospitals. Data from hypotensive and non-hypotensive patients were compared to identify clinical correlates of hypotension. We also evaluated the association between clinical parameters (including hypotension) and in-hospital mortality.

RESULTS

The incidence of hypotension in AOPP patients was 16.4%. Hypotensive patients showed significantly higher in-hospital mortality (1.1% vs. 39.9%, P<0.001). Advanced age (odds ratio [OR] 1.25, 95% confidence interval [CI] 1.08-1.44), history of diabetes (OR 2.65, 95% CI 1.14-5.96), and increased white blood cell count (OR 1.06, 95% CI 1.03-1.09), plasma cholinesterase (OR 0.91, 95% CI 0.84-0.94), plasma albumin (OR 0.88, 95% CI 0.85-0.92), serum amylase (OR 1.01, 95% CI 1.01-1.02), and blood pH (OR 0.64, 95% CI 0.54-0.75) were significantly associated with hypotension. After adjusting for potential confounders, hypotension was associated with increased in-hospital mortality (hazard ratio 8.77-37.06, depending on the controlled variables).

CONCLUSIONS

Hypotension is a common complication of AOPP and is associated with increased in-hospital mortality. Advanced age, history of diabetes, and changes in laboratory parameters were associated with hypotension in AOPP patients.

Effect of Fast-Disintegrating Tablets' Characteristics on the Sublingual Permeability of Atropine Sulfate for the Potential Treatment of Organophosphates Toxicity

Atropine sulfate (AS) fast-disintegrating sublingual tablets (FDSTs) were tested for AS sublingual permeation's feasibility as a potential alternative dosage form to treat organophosphates (OP) toxicity. More than 12,000 OP pesticide toxicity cases were reported in the USA from 2011 to 2014. AS is the recommended antidote for OP toxicity; however, it is only available as an ATROPEN® auto-injector, an IM injection, for self-administration, which is associated with several drawbacks and limitations. Six AS FDST batches were formulated and characterized. Two tablet sizes, group A weighing 150 mg and group B weighing 50 mg, were formulated with three different AS doses: 2 mg (A1 and B1), 4 mg (A2 and B2), and 8 mg (A3 and B3). AS in vitro diffusion and sublingual permeation were investigated in Franz cells using a cellulose membrane and an excised porcine sublingual membrane. The effect of AS load and tablet size on sublingual permeation was also evaluated. All batches passed quality control tests. AS FDSTs' size and AS load had a significant effect on tablet disintegration time and drug dissolution, which significantly impacted AS concentration gradient across the diffusional membrane. Group B FDSTs (smaller tablets) resulted in a significantly higher initial permeation (JAUC_0-15) compared to group A FDSTs. Also, the cumulative AS (JAUC_0-90) and AS influx (J) increased linearly with increasing AS dose. These AS FDSTs have the potential to be explored in vivo to determine the required bioequivalent sublingual AS dose as an alternative dosage form for the treatment of OP toxicity.

Pulmonary thrombosis in acute organophosphate poisoning-Case report and literature overview of prothrombotic preconditioning in organophosphate toxicity

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Acute OP poisoning complicated with pulmonary thrombosis during the first week of poisoning.

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Antidote treatment included atropine, whereas diazepam was administered in the first 48 h.

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There was no administration of oximes due to unavailability.

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Prolonged hypoxemia in acute OP intoxication indicates exclusion of thrombotic pulmonary event.

Objective

Acute organophosphate (OP) poisonings are presented with acetylcholine-receptor overstimulation. There have been a few case reports of thrombotic complications in acute OP poisonings, as well as prolonged thrombosis preconditions in patients who survived this type of intoxications. The paper presents a case with pulmonary thrombosis (PT) that develops in the subacute phase of intentional acute OP poisoning, treated only with atropine, as well as a literature overview of OP-induced prothrombotic toxicity.

Case report

A middle aged woman was brought to the hospital after ingestion of unknown insecticide with suicidal intentions. She had a history of HTA (arterial hypertension), hyperlipidemia and untreated depression. The clinical features of poisoning were miosis, vomiting, dizziness, abdominal cramps and diarrhea. Soon after admission, she developed difficulties in breathing with decrease of serum pseudocholinesterase (2590...1769...1644...800 U/l), bibasal pulmonary crackles, drop of SpO₂ to 84%. Antidote treatment included carbo medicinalis, atropine, and diazepam, without use of oximes. The seventh day pseudocholinesterase, the levels started to rise but the patient’s hyposaturation (SpO₂ 86-88%) persisted. Chest ultrasound detected hypoechoic subpleural lesion to the right. Haemostatic tests showed increased D-Dimmer (2312 ng/ml) with hypercoagulability. The CT pulmonary angiography confirmed PT and after the administration of low molecular heparin, her clinical condition improved.

Conclusion

Acute organophosphate poisoning treated with atropine showed a potential for inducing prothrombotic coagulation abnormalities, presented with PT. This life-threatening complication may additionally contribute to prolonged morbidity and mortality in OP poisonings, especially in patients with medical history of comorbidites.

Clinical features of organophosphate poisoning: A review of different classification systems and approaches

PURPOSE

The typical toxidrome in organophosphate (OP) poisoning comprises of the Salivation, Lacrimation, Urination, Defecation, Gastric cramps, Emesis (SLUDGE) symptoms. However, several other manifestations are described. We review the spectrum of symptoms and signs in OP poisoning as well as the different approaches to clinical features in these patients.

MATERIALS AND METHODS

Articles were obtained by electronic search of PubMed(®) between 1966 and April 2014 using the search terms organophosphorus compounds or phosphoric acid esters AND poison or poisoning AND manifestations.

RESULTS

Of the 5026 articles on OP poisoning, 2584 articles pertained to human poisoning; 452 articles focusing on clinical manifestations in human OP poisoning were retrieved for detailed evaluation. In addition to the traditional approach of symptoms and signs of OP poisoning as peripheral (muscarinic, nicotinic) and central nervous system receptor stimulation, symptoms were alternatively approached using a time-based classification. In this, symptom onset was categorized as acute (within 24-h), delayed (24-h to 2-week) or late (beyond 2-week). Although most symptoms occur with minutes or hours following acute exposure, delayed onset symptoms occurring after a period of minimal or mild symptoms, may impact treatment and timing of the discharge following acute exposure. Symptoms and signs were also viewed as an organ specific as cardiovascular, respiratory or neurological manifestations. An organ specific approach enables focused management of individual organ dysfunction that may vary with different OP compounds.

CONCLUSIONS

Different approaches to the symptoms and signs in OP poisoning may better our understanding of the underlying mechanism that in turn may assist with the management of acutely poisoned patients.

Effects of Organophosphate Insecticides on Mechanical Properties of Rat Aorta

The present study was carried out to search whether organophosphate pesticides affect the mechanical properties of the thoracic aorta. Wistar female rats (aged 6-8 weeks) were assigned randomly to a control group and groups treated with either dichlorvos or chlorpyriphos for 90 days at a dose of 5 mg/kg/day. After that period, animals were killed and thoracic aorta strips in longitudinal direction were isolated. The stress, strain and elastic modulus were obtained from the strips. Our results showed that chronic administration of chlorpyriphos and dichlorvos caused downward shift of the stress-strain relations compared to the control curve. The elastic modulus-stress curve revealed distinct characteristics in the low and high stress regions. A power function was used to simulate the low stress region while a line was fit to the high stress region. Curve fitting procedure illustrated that both pesticides influenced mainly the high stress region, but they had diverse effects at the low stress region. The results also imply that chlorpyriphos and dichlorvos decrease the strength of the aorta and therefore might influence the response of the aorta to mechanical loading induced by blood pressure.

Hypotension in severe dimethoate self-poisoning

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.

Management of acute organophosphorus pesticide poisoning

Organophosphorus pesticide self-poisoning is an important clinical problem in rural regions of the developing world, and kills an estimated 200,000 people every year. Unintentional poisoning kills far fewer people but is a problem in places where highly toxic organophosphorus pesticides are available. Medical management is difficult, with case fatality generally more than 15%. We describe the limited evidence that can guide therapy and the factors that should be considered when designing further clinical studies. 50 years after first use, we still do not know how the core treatments--atropine, oximes, and diazepam--should best be given. Important constraints in the collection of useful data have included the late recognition of great variability in activity and action of the individual pesticides, and the care needed cholinesterase assays for results to be comparable between studies. However, consensus suggests that early resuscitation with atropine, oxygen, respiratory support, and fluids is needed to improve oxygen delivery to tissues. The role of oximes is not completely clear; they might benefit only patients poisoned by specific pesticides or patients with moderate poisoning. Small studies suggest benefit from new treatments such as magnesium sulphate, but much larger trials are needed. Gastric lavage could have a role but should only be undertaken once the patient is stable. Randomised controlled trials are underway in rural Asia to assess the effectiveness of these therapies. However, some organophosphorus pesticides might prove very difficult to treat with current therapies, such that bans on particular pesticides could be the only method to substantially reduce the case fatality after poisoning. Improved medical management of organophosphorus poisoning should result in a reduction in worldwide deaths from suicide.

Nerve agents: a comprehensive review

Nerve agents are perhaps the most feared of potential agents of chemical attack. The authors review the history, physical characteristics, pharmacology, clinical effects, and treatment of these agents.

Speed of Initial Atropinisation in Significant Organophosphorus Pesticide Poisoning—A Systematic Comparison of Recommended Regimens

OBJECTIVE

Early deaths from organophosphorus (OP) pesticide self-poisoning result from respiratory failure and cardiovascular collapse. Therapy requires the urgent use of atropine to reverse cholinergic excess, thereby improving respiratory function, heart rate, and blood pressure. We aimed to assess variation in textbook recommendations for early atropinisation and to see whether this variation affected time to stabilisation using model data from 22 severely poisoned patients seen in a Sri Lankan clinical trial.

METHODS

We extracted prospectively recorded data on atropine requirements for 22 OP poisoned patients who required intubation but survived to discharge. We did a systematic search for textbook recommendations for initial atropinisation regimens. These regimens were then applied to data from the Sri Lankan patients.

RESULTS

The patients required a mean of 23.4 mg (standard deviation 22.0, range 1-75 mg) atropine to clear the lungs, raise the pulse above 80 bpm, and restore systolic blood pressure to more than 80 mmHg. Textbook recommendations varied markedly--atropinisation of an average patient, requiring the mean dose of 23.4 mg, would have taken 8 to 1380 mins; atropinisation of a very ill patient, requiring 75 mg, would have taken 25 to 4440 mins. Atropinisation was attained most rapidly with a regimen of increasing bolus doses after failure to respond to the previous bolus.

CONCLUSIONS

There is great variation in recommendations for atropinisation, with some regimens taking hours and even days to stabilise a patient. The guidelines are very flexible--possibly appropriate for experienced emergency physicians or clinical toxicologists, but completely inappropriate for the inexperienced junior doctors who see most cases worldwide. We recommend that a consensus guideline be developed by appropriate organisations to bring order to this important part of OP therapy, while acknowledging the paucity of data to drive the guidelines.

[Acute neurotoxic organophosphate poisoning: insecticides and chemical weapons]

OBJECTIVE

To review clinical and therapeutic bases of an organophosphate poisoning, either with insecticide or nerve agent.

DATA SOURCES

References were obtained from computerized bibliographic research (Medline), from personal data (academic memoir, documents under approbation of the National Defense Office), from Internet's data.

DATA SYNTHESIS

Generally, organophosphate poisoning occurs during accidental exposure with agricultural insecticide or suicide. The effects of organophosphate compounds are due to the inhibition of the enzyme acetylcholinesterase. The intoxication symptoms can be divided into muscarine-like, nicotine-like effects, effects on the central nervous system and symptoms related to the dysfunction of the neuromuscular junction. The interest of biological acetylcholinesterase's measuring is minimal because it is weakly specific or sensitive. The immediate severity is due to hypoxia. Respiratory failure results from the lack of central drive inflated with excessive bronchial secretions, bronchospasm and respiratory muscles paralysis. The secondary complications are early myopathies whose gravity is correlated with the decrease of acetylcholinesterases, or later neuropathies induced by a different mechanism. Beside the symptomatic measures, atropine is the specific anticholinergic treatment. When promptly used, oximes can regenerate cholinesterases. The attempted effects of the treatment are mouth dryness, pupilar dilatation and flushing of the skin. Nerve agents are lethal toxics which have a short onset time and produce severe neurological pathology. In a terrorist incident, it is as important to identify rapidly the toxic agent and provide emergency decontamination as to manage medical care. An effective response must be multidisciplinary, involving clinicians, toxicologists, Emergency Medical Service and public's health personnel.