Bioscavenger therapy for organophosphate poisoning – an open-labeled pilot randomized trial comparing fresh frozen plasma or albumin with saline in acute organophosphate poisoning in humans

Evaluation of the effectiveness of fresh frozen plasma transfusion as adjuvant treatment in acute organophosphate-poisoned patients: A randomized clinical trial

Organophosphorus (OP) poisoning is a significant cause of morbidity and mortality worldwide. Recent research has explored new approaches to improving treatment options, which present several challenges. This study aimed to evaluate the role of fresh frozen plasma (FFP) as an adjunctive therapy for acute OP intoxication. A prospective single-blinded randomized clinical trial was conducted on patients of both sexes admitted to the Intensive Care Unit (ICU) of the Poison Control Center at Ain Shams University Hospital (PCC-ASUH) with acute OP toxicity during the period from the beginning of August 2022 to the end of July 2023. According to the Peradeniya score, Group I consisted of 48 patients (52%) with moderate OP poisoning, and Group II consisted of 44 patients (48%) with severe OP poisoning. Patients in the moderate group were assigned to receive either standard treatment (Group Ia, n = 24) or standard treatment plus FFP (Group Ib, n = 24). In addition, patients in the severe group were assigned to receive either standard treatment (Group IIa, n = 22) or standard treatment plus FFP (Group IIb, n = 22). A total of 46 patients received FFP transfusion. The authors demonstrated that the early use of a total of nine packs of FFP (250 mL each) over three consecutive days significantly reduced the total doses of atropine and oximes, the total hospitalization period, and the requirement for mechanical ventilation in patients with OP poisoning, both in the moderate and severe groups.

Quantification of Organophosphorus Insecticide Removed by Gastric Lavage in Acutely Poisoned Patients: An Observational Study

Introduction

The effectiveness of gastric lavage in organophosphorus (OP) poisoning has not been established. We assessed the ability of gastric lavage to remove OP insecticides as a preliminary stage in assessing effectiveness.

Patients and methods

Organophosphorus poisoning patients presenting within 6 hours were included, irrespective of prior gastric lavage. A nasogastric tube was placed and gastric contents aspirated, followed by at least three cycles of gastric lavage with 200 mL of water. Samples from the initial aspirate and the first three lavage cycles were sent for identification and quantification of the OP compounds. Patients were monitored for complications of gastric lavage.

Results

Around 42 patients underwent gastric lavage. Eight (19.0%) patients were excluded from the study because of a lack of analytical standards for ingested compounds. Insecticides were detectable in the lavage samples of 24 of 34 (70.6%) patients. Lipophilic OP compounds were detected in 23 of 24 patients, while no hydrophilic OP compounds could be detected in six patients with reported ingestion of hydrophilic compounds. For chlorpyrifos poisoning (n = 10), only 0.65 mg (SD 1.2) of the estimated ingested amount (n = 5) of 8,600 mg (SD 3,200) was recovered by gastric lavage. The mean proportion of the compound removed by initial gastric aspirate was 79.4% and subsequent three cycles removed 11.5, 6.6, and 2.7%.

Conclusion

Lipophilic OP insecticides could be quantified in the stomach contents of OP poisoning patients with the first aspiration or lavage being most effective. The amount removed was very low; hence, routine use of gastric lavage for OP poisoning patients arriving within 6 hours is unlikely to be beneficial.

How to cite this article

Mathansingh AJ, Jose A, Fleming JJ, Abhilash KPP, Chandiraseharan VK, Lenin A, et al. Quantification of Organophosphorus Insecticide Removed by Gastric Lavage in Acutely Poisoned Patients: An Observational Study. Indian J Crit Care Med 2023;27(6):397-402.

Organophosphorus Poisoning: Acute Respiratory Distress Syndrome (ARDS) and Cardiac Failure as Cause of Death in Hospitalized Patients

Industrial production of food for animals and humans needs increasing amounts of pesticides, especially of organophosphates, which are now easily available worldwide. More than 3 million cases of acute severe poisoning are estimated to occur worldwide every year, and even more cases remain unreported, while 200,000–350,000 incidentally or intentionally poisoned people die every year. Diagnostic and therapeutic procedures in organophosphate poisoning have, however, remained unchanged. In addition to several neurologic symptoms (miosis, fasciculations), hypersecretion of salivary, bronchial, and sweat glands, vomiting, diarrhea, and loss of urine rapidly induce dehydration, hypovolemia, loss of conscience and respiratory distress. Within hours, signs of acidosis due to systemic hypoxia can be observed at first laboratory investigation after hospitalization. While determination of serum-cholinesterase does not have any diagnostic value, it has been established that hypoalbuminemia alone or accompanied by an increase in creatinine, lactate, or C-reactive protein serum levels has negative prognostic value. Increased serum levels of C-reactive protein are a sign of systemic ischemia. Protective mechanical ventilation should be avoided, if possible. In fact, acute respiratory distress syndrome characterized by congestion and increased weight of the lung, accompanied by heart failure, may become the cause of death. As the excess of acetylcholine at the neuronal level can persist for weeks until enough newly, locally synthesized acetylcholinesterase becomes available (the value of oximes in reducing this time is still under debate), after atropine administration, intravenous albumin and fluid infusion should be the first therapeutic interventions to reestablish normal blood volume and normal tissue oxygenation, avoiding death by cardiac arrest.

Molecular Mechanisms of Acute Organophosphate Nephrotoxicity

Organophosphates (OPs) are toxic chemicals produced by an esterification process and some other routes. They are the main components of herbicides, pesticides, and insecticides and are also widely used in the production of plastics and solvents. Acute or chronic exposure to OPs can manifest in various levels of toxicity to humans, animals, plants, and insects. OPs containing insecticides were widely used in many countries during the 20th century, and some of them continue to be used today. In particular, 36 OPs have been registered in the USA, and all of them have the potential to cause acute and sub-acute toxicity. Renal damage and impairment of kidney function after exposure to OPs, accompanied by the development of clinical manifestations of poisoning back in the early 1990s of the last century, was considered a rare manifestation of their toxicity. However, since the beginning of the 21st century, nephrotoxicity of OPs as a manifestation of delayed toxicity is the subject of greater attention of researchers. In this article, we present a modern view on the molecular pathophysiological mechanisms of acute nephrotoxicity of organophosphate compounds.

Pneumothorax and Pneumomediastinum Complicating Organophosphate Poisoning: A Case Series of Complications Less Understood

Organophosphate compounds are used as insecticides in agricultural and domestic settings throughout the world. Acute organophosphorus (OP) poisoning is a major public health issue. Early diagnosis of OP poisoning and prompt atropinization can save lives. Respiratory failure may occur in patients with OP poisoning for many reasons, including aspiration of gastric contents, excessive secretions, pneumonia, and sepsis complicating acute respiratory distress syndrome. Till date, however, spontaneous pneumothorax and pneumomediastinum have not been reported in cases of OP poisoning. This report presents two similar cases of OP poisoning in which spontaneous pneumothorax and pneumomediastinum developed following OP ingestion.

Efficacy of fresh frozen plasma transfusion in comparison with conventional regimen in organophosphate poisoning treatment: a meta-analysis study

OBJECTIVE

To evaluating the efficacy of fresh frozen plasma (FFP) in comparison with conventional regimen in the treatment of organophosphate (OP) poisoning.

METHODS

PubMed, ScopeMed, Cochrane, Scopus, and Google Scholar databases were searched. The search strategy used the following key words "organophosphate" and "poisoning or toxicity", "(atropine and oxime)", "fresh frozen plasma", "clinical trial", "outcome". The treatment with atropine or/and oxime was considered conventional therapy. The length of hospitalization, the length of ICU admission, need for mechanical ventilation and its duration, clinical recovery point, choline esterase level, mortality rate, and intermediate syndrome (IMS) occurrence were the key outcomes of interest. Databases were searched during the period of 2003-2019. Five studies were included in the analysis.

RESULTS

Pooling of data showed that the relative risk (RR) of mortality in OP poisoning for five included trials comparing FFP-treated group with conventional regimen therapy was [0.563 (95% CI (0.252, 1.255)]. The summary of RR for IMS in two studies was [RR: 1.34, 95% CI (0.655, 2.742)]. In addition, there was a non-significant mean difference (MD) in hospital stay [MD: -0.106, 95% CI (-0.434, 0.223)] in three included trials. A significant MD was observed in the length of ICU admission in two trials between FFP-treated group compared to the conventional treatment group [MD: -2.672, 95% CI (-4.189, -1.154)], but after random effects meta-analysis, the changes were not significant [MD: -2.015, 95% CI (-6.308, 2.277)]. The summary of fixed-effect meta-analysis for choline esterase level in three trails was [MD: -0.117, 95% CI (-0.468, 0.234)]. The RR of ventilation requirement for two included trials in the FFP-treated group comparing to the conventional regimen therapy was [0.84, 95% CI (0.691, 1.022)] while for ventilation duration in two studies was [MD: -0.183, 95% CI (-0.567, 0.201)].

CONCLUSION

The addition of FFP to conventional therapy did not improve the outcomes of mortality, IMS, hospital length of stay, cholinesterase levels, need or duration of mechanical ventilation, and only the length of ICU stay could affect in the treated group.

Investigating the Effect of Fresh Frozen Plasma and Albumin on DNA Damage and Oxidative Stress Biomarkers in Poisoning Cases by Organophosphates

The efficacy of albumin and fresh frozen plasma (FFP) and their effects on biomarkers of oxidative stress has been evaluated. In a randomized clinical control trial, 33 poisoned patients by Organophosphate (OP) were enrolled in the research and divided into three groups. The first group underwent conventional treatments by atropine and pralidoxime (control group); the second and third groups, in addition to traditional treatments, received albumin and FFP. Cholinesterase (ChE) enzyme activity, total antioxidant capacity (TAC), serum thiol groups (TTG), malonyl aldehyde (MDA) and DNA damage were measured in all treatment and control groups. Patients were matched in terms of demographic characteristics at the beginning of the study. ChE activity was increased in all three groups during treatment, which was more noticeable in the FFP group and was statistically significant in both albumin and FFP group compared to the control group (p<0.05). TAC increased, and TTG decreased in FFP and albumin groups compared to the control group; no significant difference was observed. MDA decreased in albumin and FFP and was significantly different in the FFP group compared to the control group (p<0.05). The amount of DNA damage in FFP and albumin groups decreased, and there was a significant difference compared to the control group (p<0.05). According to the results of this study, due to the decrease of oxidative damage parameters and the increase of antioxidant parameters in albumin and specially FFP groups, FFP may be considered as an adjunctive treatment for OP poisoning.

A case report of cholinesterase inhibitor poisoning: cholinesterase activities and analytical methods for diagnosis and clinical decision making

Suicidal ingestion of organophosphorus (OP) or carbamate (CM) compounds challenges health care systems worldwide, particularly in Southeast Asia. The diagnosis and treatment of OP or CM poisoning is traditionally based on the clinical appearance of the typical cholinergic toxidrome, e.g. miosis, salivation and bradycardia. Yet, clinical signs might be inconclusive or even misleading. A current case report highlights the importance of enzymatic assays to provide rapid information and support clinicians in diagnosis and rational clinical decision making. Furthermore, the differentiation between OP and CM poisoning seems important, as an oxime therapy will most probably not provide benefit in CM poisoning, but—as every pharmaceutical product—it might result in adverse effects. The early identification of the causing agent and the amount taken up in the body are helpful in planning of the therapeutic regimen including experimental strategies, e.g. the use of human blood products to facilitate scavenging of the toxic agent. Furthermore, the analysis of biotransformation products and antidote levels provides additional insights into the pathophysiology of OP or CM poisoning. In conclusion, cholinesterase activities and modern analytical methods help to provide a more effective treatment and a thorough understanding of individual cases of OP or CM poisoning.

Antidotes in Poisoning

Introduction

Antidotes are agents that negate the effect of a poison or toxin. Antidotes mediate its effect either by preventing the absorption of the toxin, by binding and neutralizing the poison, antagonizing its end-organ effect, or by inhibition of conversion of the toxin to more toxic metabolites. Antidote administration may not only result in the reduction of free or active toxin level, but also in the mitigation of end-organ effects of the toxin by mechanisms that include competitive inhibition, receptor blockade or direct antagonism of the toxin.

Mechanism of action of antidotes

Reduction in free toxin level can be achieved by specific and non-specific agents that bind to the toxin. The most commonly used non-specific binding agent is activated charcoal. Specific binders include chelating agents, bioscavenger therapy and immunotherapy. In some situations, enhanced elimination can be achieved by urinary alkalization or hemadsorption. Competitive inhibition of enzymes (e.g. ethanol for methanol poisoning), enhancement of enzyme function (e.g. oximes for organophosphorus poisoning) and competitive receptor blockade (e.g. naloxone, flumazenil) are other mechanisms by which antidotes act. Drugs such as N-acetyl cysteine and sodium thiocyanate reduce the formation of toxic metabolites in paracetamol and cyanide poisoning respectively. Drugs such as atropine and magnesium are used to counteract the end-organ effects in organophosphorus poisoning. Vitamins such as vitamin K, folic acid and pyridoxine are used to antagonise the effects of warfarin, methotrexate and INH respectively in the setting of toxicity or overdose. This review provides an overview of the role of antidotes in poisoning.

How to cite this article

Chacko B, Peter JV. Antidotes in Poisoning. Indian J Crit Care Med 2019;23(Suppl 4):S241-S249.

Respiratory complications of organophosphorus nerve agent and insecticide poisoning. Implications for respiratory and critical care

Organophosphorus (OP) compound poisoning is a major global public health problem. Acute OP insecticide self-poisoning kills over 200,000 people every year, the majority from self-harm in rural Asia. Highly toxic OP nerve agents (e.g., sarin) are a significant current terrorist threat, as shown by attacks in Damascus during 2013. These anticholinesterase compounds are classically considered to cause an acute cholinergic syndrome with decreased consciousness, respiratory failure, and, in the case of insecticides, a delayed intermediate syndrome that requires prolonged ventilation. Acute respiratory failure, by central and peripheral mechanisms, is the primary cause of death in most cases. However, preclinical and clinical research over the last two decades has indicated a more complex picture of respiratory complications after OP insecticide poisoning, including onset of delayed neuromuscular junction dysfunction during the cholinergic syndrome, aspiration causing pneumonia and acute respiratory distress syndrome, and the involvement of solvents in OP toxicity. The treatment of OP poisoning has not changed over the last 50 years. However, a better understanding of the multiple respiratory complications of OP poisoning offers additional therapeutic opportunities.

Advances in toxicology and medical treatment of chemical warfare nerve agents

Organophosphorous (OP) Nerve agents (NAs) are known as the deadliest chemical warfare agents. They are divided into two classes of G and V agents. Most of them are liquid at room temperature. NAs chemical structures and mechanisms of actions are similar to OP pesticides, but their toxicities are higher than these compounds. The main mechanism of action is irreversible inhibition of Acetyl Choline Esterase (AChE) resulting in accumulation of toxic levels of acetylcholine (ACh) at the synaptic junctions and thus induces muscarinic and nicotinic receptors stimulation. However, other mechanisms have recently been described. Central nervous system (CNS) depression particularly on respiratory and vasomotor centers may induce respiratory failure and cardiac arrest. Intermediate syndrome after NAs exposure is less common than OP pesticides poisoning. There are four approaches to detect exposure to NAs in biological samples: (I) AChE activity measurement, (II) Determination of hydrolysis products in plasma and urine, (III) Fluoride reactivation of phosphylated binding sites and (IV) Mass spectrometric determination of cholinesterase adducts. The clinical manifestations are similar to OP pesticides poisoning, but with more severity and fatalities. The management should be started as soon as possible. The victims should immediately be removed from the field and treatment is commenced with auto-injector antidotes (atropine and oximes) such as MARK I kit. A 0.5% hypochlorite solution as well as novel products like M291 Resin kit, G117H and Phosphotriesterase isolated from soil bacterias, are now available for decontamination of NAs. Atropine and oximes are the well known antidotes that should be infused as clinically indicated. However, some new adjuvant and additional treatment such as magnesium sulfate, sodium bicarbonate, gacyclidine, benactyzine, tezampanel, hemoperfusion, antioxidants and bioscavengers have recently been used for OP NAs poisoning.

Is fresh-frozen plasma clinically effective? An update of a systematic review of randomized controlled trials

BACKGROUND

The clinical use of frozen plasma (FP) continues to increase, both in prophylactic and in therapeutic settings. In 2004, a systematic review of all published randomized controlled trials (RCTs) revealed a lack of evidence that supported the efficacy of FP use. This is an update that includes all new RCTs published since the original review.

STUDY DESIGN AND METHODS

Trials involving transfusion of FP up to July 2011 were identified from searches of MEDLINE, EMBASE, CINAHL, The Cochrane Library, and the UKBTS/SRI Transfusion Evidence Library. Methodologic quality was assessed. The primary outcome measure was the effect of FP on survival.

RESULTS

Twenty-one new trials were eligible for inclusion. These covered prophylactic and therapeutic FP use in liver disease, in cardiac surgery, for warfarin anticoagulation reversal, for thrombotic thrombocytopenic purpura treatment, for plasmapheresis, and in other settings, including burns, shock, and head injury. The largest number of recent RCTs were conducted in cardiac surgery; meta-analysis showed no significant difference for FP use for the outcome of 24-hours postoperative blood loss (weighted mean difference, -35.24 mL; 95% confidence interval, -84.16 to 13.68 mL). Overall, there was no significant benefit for FP use across all the clinical conditions. Only two of the 21 trials fulfilled all the criteria for quality assessment.

CONCLUSION

Combined with the 2004 review, 80 RCTs have investigated FP with no consistent evidence of significant benefit for prophylactic and therapeutic use across a range of indications evaluated. There has been little improvement in the overall methodologic quality of RCTs conducted in the past few years.