Prognosis and treatment of paraquat poisoning: a review of 28 cases

Differential Effects of Paraquat, Rotenone, and MPTP on Cellular Bioenergetics of Undifferentiated and Differentiated Human Neuroblastoma Cells

Paraquat (PQ), rotenone (RO), and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are neurotoxicants that can damage human health. Exposure to these neurotoxicants has been linked to neurodegeneration, particularly Parkinson's disease. However, their mechanisms of action have not been fully elucidated, nor has the relative vulnerability of neuronal subtypes to their exposures. To address this, the current study investigated the cytotoxic effects of PQ, RO, and MPTP and their relative effects on cellular bioenergetics and oxidative stress on undifferentiated human neuroblastoma (SH-SY5Y) cells and those differentiated to dopaminergic (DA) or cholinergic (CH) phenotypes. The tested neurotoxicants were all cytotoxic to the three cell phenotypes that correlated with both concentration and exposure duration. At half-maximal effective concentrations (EC50s), there were significant reductions in cellular ATP levels and reduced activity of the mitochondrial complexes I and III, with a parallel increase in lactate production. PQ at 10 µM significantly decreased ATP production and mitochondrial complex III activity only in DA cells. RO was the most potent inhibitor of mitochondrial complex 1 and did not inhibit mitochondrial complex III even at concentrations that induced a 50% loss of cell viability. MPTP was the most potent toxicant in undifferentiated cells. All neurotoxicants significantly increased reactive oxygen species, lipid peroxidation, and nuclear expression of Nrf2, with a corresponding inhibition of the antioxidant enzymes catalase and superoxide dismutase. At a 10 µM exposure to PQ or RO, oxidative stress biomarkers were significant in DA cells. Collectively, this study underscores the importance of mitochondrial dysfunction and oxidative stress in PQ, RO, and MPTP-induced cytotoxicity and that neuronal phenotypes display differential vulnerability to these neurotoxicants.

The efficacy of hemodialysis on paraquat poisoning mortality: A systematic review and meta-analysis

BACKGROUND

Paraquat (PQ) poisoning is a serious public health concern, especially in developing countries, due to its easy access and lack of awareness of potential harms. No effective treatment has been reported yet. Conventional hemodialysis (HD) is still used in many centers for excreting PQ or reducing acute kidney injury, but there is no consensus on its efficacy. Therefore, we aimed to review the HD efficacy in PQ poisoning mortality.

MATERIALS AND METHODS

We searched Web of Science, PubMed, Excerpta Medical Database, Google Scholar, Scopus, Cochrane, Web of Knowledge, Pro-Quest, ScienceDirect, Springer, Clinical Key, Scientific Information Database, Magiran, and Iran-doc, in publications before January 1, 2020. We compared patients who underwent HD (Group 1) with those who did not (Group 2). The outcome was considered mortality/survival. The data were analyzed by Comprehensive Meta-analysis Software.

RESULTS

This systematic review and meta-analysis included five studies with a combined total of 203 patients. The patients in the Group 1 had higher mortality than Group 2 (odds ratio, 2.84; 95% confidence interval: 1.22-6.64; P = 0.02). There was no evidence of publication bias (P value for Egger's test = 0.833).

CONCLUSION

Although HD did not affect the survival of patients, other variables such as the amount of ingested PQ, poisoning severity, the time between PQ ingestion and the start of HD, duration, and times of HD sessions may influence the results regarding mortality.

Evidence for the efficacy of the emetic PP796 in paraquat SL20 formulations - a narrative review of published and unpublished evidence

BACKGROUND

The bipyridyl herbicide paraquat was first introduced into agriculture in the 1960s by Imperial Chemical Industries. Due to issues with unintentional poisoning, the centrally acting emetic PP796 was added in 1976 to the company's 20% paraquat ion soluble liquid (SL20) formulations (Gramoxone^®) at a concentration of 0.5 g/L or 0.05% (equivalent to 0.071 mg/kg in a 70 kg adult ingesting a minimum lethal dose of 10 mL) to induce early vomiting (within 30 min), reduce paraquat absorption from the gut, and prevent deaths. Its presence in paraquat products was subsequently mandated by the Food and Agriculture Organization Committee of Experts on Pesticides in Agriculture (predecessor to the current FAO/WHO Joint Meeting on Pesticide Specifications). However, no primary pre-clinical or clinical data have been published regarding the effectiveness of PP796. We reviewed the published literature and unpublished company reports for data on the effectiveness of PP796.

METHODS

PubMed and Google were searched for published studies on the emetic using the search terms "paraquat" and ["emetic" or "PP796"]. Company documents reporting pre-clinical and clinical studies were accessed at the website of U.S. Right to Know (https://usrtk.org/pesticides/paraquat-papers/). Primary study reports were sought as well as overviews written by company toxicologists.

RESULTS

Pre-clinical dog and monkey studies indicated that the PP796 EC50 dose for vomiting was around 0.5-2 mg/kg. Further increasing the PP796 concentration speeded up the time to first vomit and reduced the amount of paraquat absorbed (as assessed by the 0-24 h plasma area-under-the-curve) 100-fold compared to a control group receiving no PP796. However, the dose selected for paraquat SL20 formulations by the company (0.5 g/L or 0.05%) was based exclusively on a phase II study in the early 1970s involving five volunteers receiving 3 different doses, with only two individuals actually vomiting, supplemented by data from 37 patients taking 2 mg in clinical trials. A UK-mandated toxicovigilance study in the 1980s identified only 21 patients ingesting paraquat SL20 with PP796 for whom data on time to vomit was available; of these patients, 11 vomited within 30 min (52.4%, 95%CI 31-73.7%). No effect on mortality could be identified from any study of paraquat SL containing 0.05% PP796. A clinical study in Sri Lanka 30 years after the emetic was first introduced, of a revised formulation (Gramoxone^® Inteon) containing a three-fold higher amount of PP796, as well as MgSO4 and an alginate, showed increased rates of early vomiting and modestly reduced mortality for patients ingesting up to 100 mL.

CONCLUSION

Pre-clinical studies showed a clear dose response for PP796 to cause early vomiting, with effective doses in the 0.5-20 mg/kg range. A too low concentration of PP796 was selected for paraquat formulations based on an inadequate phase II study. Currently, evidence that PP796 at 0.05% in paraquat SL20 causes more rapid vomiting after ingestion is weak or unpublished; no evidence of clinical benefit or fewer deaths has been identified. There is no evidence to support the FAO/WHO Joint Meeting on Pesticide Specifications mandate to include PP796 or any other emetic in paraquat products. Products with higher emetic concentrations have been developed but are not widely used; it is possible they may prevent deaths.

Thoracic Society of Australia and New Zealand Position Statement on Acute Oxygen Use in Adults: 'Swimming between the flags'

Oxygen is a life-saving therapy but, when given inappropriately, may also be hazardous. Therefore, in the acute medical setting, oxygen should only be given as treatment for hypoxaemia and requires appropriate prescription, monitoring and review. This update to the Thoracic Society of Australia and New Zealand (TSANZ) guidance on acute oxygen therapy is a brief and practical resource for all healthcare workers involved with administering oxygen therapy to adults in the acute medical setting. It does not apply to intubated or paediatric patients. Recommendations are made in the following six clinical areas: assessment of hypoxaemia (including use of arterial blood gases); prescription of oxygen; peripheral oxygen saturation targets; delivery, including non-invasive ventilation and humidified high-flow nasal cannulae; the significance of high oxygen requirements; and acute hypercapnic respiratory failure. There are three sections which provide (1) a brief summary, (2) recommendations in detail with practice points and (3) a detailed explanation of the reasoning and evidence behind the recommendations. It is anticipated that these recommendations will be disseminated widely in structured programmes across Australia and New Zealand.

Inclusion complexation and self-association of cucurbit[n]uril (n = 6, 7) and diquat under pseudo-physiological conditions

The formation and steric structure of the inclusion complex of cucurbit[n]uril (CB[n]; n = 6, 7) and diquat (DQ) were investigated through NMR measurements under the pH conditions of human pseudo-gastric or body fluids, in physiological saline.

Paraquat-induced acute kidney and liver injury: Case report of a survivor from Bangladesh

Despite high fatality following paraquat ingestion, a few percentages of patients survive even after organ damage appears. We need to focus more on careful clinical and laboratory monitoring. Early diagnosis and Supportive therapy are crucial.

Hemodynamic and electromechanical effects of paraquat in rat heart

Paraquat (PQ) is a highly lethal herbicide. Ingestion of large quantities of PQ usually results in cardiovascular collapse and eventual mortality. Recent pieces of evidence indicate possible involvement of oxidative stress- and inflammation-related factors in PQ-induced cardiac toxicity. However, little information exists on the relationship between hemodynamic and cardiac electromechanical effects involved in acute PQ poisoning. The present study investigated the effects of acute PQ exposure on hemodynamics and electrocardiogram (ECG) in vivo, left ventricular (LV) pressure in isolated hearts, as well as contractile and intracellular Ca2+ properties and ionic currents in ventricular myocytes in a rat model. In anesthetized rats, intravenous PQ administration (100 or 180 mg/kg) induced dose-dependent decreases in heart rate, blood pressure, and cardiac contractility (LV +dP/dtmax). Furthermore, PQ administration prolonged the PR, QRS, QT, and rate-corrected QT (QTc) intervals. In Langendorff-perfused isolated hearts, PQ (33 or 60 μM) decreased LV pressure and contractility (LV +dP/dtmax). PQ (10-60 μM) reduced the amplitudes of Ca2+ transients and fractional cell shortening in a concentration-dependent manner in isolated ventricular myocytes. Moreover, whole-cell patch-clamp experiments demonstrated that PQ decreased the current amplitude and availability of the transient outward K+ channel (Ito) and altered its gating kinetics. These results suggest that PQ-induced cardiotoxicity results mainly from diminished Ca2+ transients and inhibited K+ channels in cardiomyocytes, which lead to LV contractile force suppression and QTc interval prolongation. These findings should provide novel cues to understand PQ-induced cardiac suppression and electrical disturbances and may aid in the development of new treatment modalities.

A novel idea for establishing Parkinson's disease mouse model by intranasal administration of paraquat

Background: In this study, we sought to provide an idea for establishing a novel mouse model for Parkinson's disease (PD) through intranasal administration of paraquat instead of the conventional method of intraperitoneal injection. Intranasal administration has the potential to lower mortality caused by intraperitoneal paraquat administration.Methods: A paraquat-loaded thermosensitive hydrogel composed of poloxamer 407 and poloxamer 188 was prepared. The survival rate of the animals was monitored upon paraquat administration nasally and intraperitoneally. The animals' behavior was also observed. Immunofluorescence staining of tyrosine hydroxylase (TH) - positive cells and western blotting of α-synuclein (α-syn)in striatum were performed. HPLC method with electrochemical detection was used to quantify monoamine neurotransmitters in striatum. Real-time RT-PCR analysis of type 1 collagen, type 3 collagen and fibronectin expression was used to evaluate pulmonary fibrosis in mice after paraquat administration.Results: The results indicated that intranasal administration of paraquat-loaded thermosensitive hydrogel can elicit Parkinsonism-like symptoms in mice. Relative to the conventional intraperitoneal injection, this strategy significantly improves survival when modeling PD and resulted in a higher loss of TH positive neurons in substantia nigra pars compacta (SNpc) and more aggregation of α-syn in striatum. Moreover, animals receiving paraquat hydrogel nasally exhibited motor disorder as well as lower levels of dopamine and dopamine metabolites in striatum when compared to those receiving paraquat intraperitoneally. The mRNA expression of collagen and fibronectinindicated that intranasal administration of paraquat was not associated with lung fibrosis.Conclusion: This strategy provides a new idea and more convenient operation for the future study of mouse model of PD.

Does Hemoperfusion Increase Survival in Acute Paraquat Poisoning? A Retrospective Multicenter Study

The efficacy of hemoperfusion (HP) in patients with acute paraquat poisoning (PQ) remains controversial. We conducted a multi-center retrospective study to include acute PQ-poisoned patients admitted to two tertiary medical centers between 2005 and 2015. We used the Severity Index of Paraquat Poisoning (SIPP) to stratify the severity of PQ-poisoned patients. The indication to start HP was a positive result for the semiquantitative urine PQ test and presentation to the hospital was within 24 h. Early HP was defined as the first session of HP performed within five hours of PQ ingestion. A total of 213 patients (100 HP group, 113 non-HP group) were eligible for the study. The overall 60-day mortality of poisoned patients was 75.6% (161/213). Multivariate Cox regression analysis showed no statistically significant difference in 60-day survival between HP and non-HP groups (95% confidence interval (CI): 0.84–1.63, p = 0.363). Further subgroup analysis in the HP group showed early HP (95% CI: 0.54–1.69, p = 0.880), and multiple secessions of HP (95% CI: 0.56–1.07, p = 0.124) were not significantly related to better survival. Among acute PQ-poisoned patients, this study found that HP was not associated with increased 60-day survival. Furthermore, neither early HP nor multiple secessions of HP were associated with survival.

Hyperamylasemia as an early predictor of mortality in patients with acute paraquat poisoning

Objective

This study aimed to evaluate the relationship between elevated serum amylase levels and the prognosis of paraquat poisoning.

Methods

Patients were categorized into the elevated and non-elevated serum amylase groups according to serum amylase levels. Demographics, mortality, risk factors of elevated serum amylase levels, and injury to the pancreas were analyzed.

Results

A total of 457 patients were enrolled in this study and the overall mortality rate was 51.9%. Patients in the elevated group had worse indices than those in the non-elevated group. Kaplan–Meier survival analysis showed that the mortality rate in the elevated group was significantly higher than that in the non-elevated group (hazard ratio: 10.65, 95% confidence interval [CI]: 7.55–15.02). Multivariate Cox proportional hazards analysis showed that elevated serum amylase levels were related to mortality (hazard ratio: 2.066, 95% CI: 1.239–3.444). The receiver operating characteristic curve showed that the area under the curve was 0.724 (95% CI: 0.666–0.783) for serum amylase levels with 70.4% sensitivity and 74.0% specificity.

Conclusion

Elevated serum amylase levels are observed in PQ poisoning. This elevation might be one of the most accurate early prognostic factors for predicting severity and mortality.

Exploring the potential benefit of natural product extracts in paraquat toxicity

Paraquat dichloride, a herbicide used for weed and grass control, is extremely toxic to humans and animals. The mechanisms of toxicity involve the redox cycling of paraquat resulting in the generation of reactive oxygen species and the depletion of the cellular NADPH. The major cause of death in paraquat poisoning is respiratory failure due to its specific uptake by and oxidative insult to the alveolar epithelial cells and inflammation with subsequent obliterating fibrosis. Paraquat also causes selective degeneration of dopaminergic neurons in the substantia nigra pars compacta, reproducing an important pathological feature of Parkinson disease. Currently, there are no antidotes for the treatment of paraquat poisoning and therapeutic management is mostly supportive and directed towards changing the disposition of the poison. The lack of effective treatments against paraquat poisoning has led to the exploration of novel compounds with antioxidant and/or anti-inflammatory properties. Recently, there is an interest in plant compounds, particularly those used in traditional medicine. Phytochemicals have been highlighted as a possible therapeutic modality for a variety of diseases due to their putative efficacies and safety. In this review, the status of plant extracts and traditional medicines in ameliorating the toxicity of paraquat is discussed.

Effect of Pulse Therapy with Glucocorticoids and Cyclophosphamide in Patients with Paraquat Poisoning

Introduction

Paraquat (PQ) is a widely used herbicide with a high mortality rate when ingested. The aim of the present study was to assess the effectiveness of repeated cyclosphosphamide (CP) and methylprednisolone (MP) combination in the treatment of PQ poisoning.

Design

Randomised, double-blinded, placebo-controlled trial.

Methods

Eligible participants were 47 patients with moderate to severe PQ poisoning within 24 hours of hospitalisation. Patients were allocated in a random fashion, 24 as the intervention and 23 as the control group. All patients received two cycles of eight hours of haemoperfusion with charcoal, and underwent emergency haemodialysis. After the dialysis, the intervention group received 15 mg/kg CP for two days and 1g MP for three days. The control group received routine supportive care. Outcome parameters, including mortality, incidence of hypoxia, hepatitis and renal failure were compared between the two groups.

Results

There were no significant differences between the two groups with regard to age, sex, baseline liver function test, creatinine, time from poisoning to dialysis, and time from poisoning to the hospitalisation. Although the incidence of hepatitis and acute renal failure did not differ significantly between the two groups, the incidence of hypoxia and mortality rate was lower in the intervention group. The number need-to-treat to reduce one mortality was 2.8.

Conclusion

The results suggest that CP and MP repeated treatment can reduce the mortality rate in moderate to severe PQ intoxication.

Clinical screening of paraquat in plasma samples using capillary electrophoresis with contactless conductivity detection: Towards rapid diagnosis and therapeutic treatment of acute paraquat poisoning in Vietnam

The employment of a purpose-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C⁴D) as a simple and cost-effective solution for clinical screening of paraquat in plasma samples for early-stage diagnosis of acute herbicide poisoning is reported. Paraquat was determined using an electrolyte composed of 10mM histidine adjusted to pH 4 with acetic acid. A detection limit of 0.5mg/L was achieved. Good agreement between results from CE-C⁴D and the confirmation method (HPLC-UV) was obtained, with relative errors for the two pairs of data better than 20% for 31 samples taken from paraquat-intoxicated patients. The results were used by medical doctors for identification and prognosis of acute paraquat poisoning cases. The objective of the work is the deployment of the developed approach in rural areas in Vietnam as a low-cost solution to reduce the mortality rate due to accidental or suicidal ingestion of paraquat.

Efficacy of Whole Bowel Irrigation Using Solutions with or without Adsorbent in the Removal of Paraquat in Dogs

1 The efficacy of whole bowel irrigation with a solution containing either polyethylene glycol (PEG) with electrolyte or an adsorbent (Kayexalate™) with a cathartic (sorbitol) was investigated in 18 dogs who had been given 250 mg kg -1 paraquat dichloride via a jejunal tube to eliminate the influence of gastric absorption.

2 Plasma paraquat concentrations 2 and 3 h after the initiation of bowel irrigation and at the end of the study (5 h later) were significantly lower in the bowel irrigation groups than in the control (no bowel irrigation) group.

3 The total body clearances of paraquat in the bowel irrigation groups were significantly greater than in the control group.

4 There were no significant differences between the two different irrigation solution groups in plasma paraquat concentration, the area under the plasma concentration time curve and the total body clearance.

5 In the PEG with electrolyte group, about 70% of the administered dose of paraquat was removed by means of bowel irrigation (n=4).

6 The adjunction of the adsorbent had no beneficial effects.

7 Haemodynamic changes associated with whole bowel irrigation were unremarkable except that right atrial and pulmonary arterial pressures were elevated in the latter part of the study.

Effect of haemoperfusion on plasma paraquat concentration in vitro and in vivo

This study was to observe the paraquat (PQ) reduction rate after haemoperfusion (HP) on the groups of a relatively large number: 50 survivors out of 105 patients with acute PQ poisoning. We started off by measuring the clearance of haemodialysis (HD) and HP for the PQ in vitro. At the blood flow of 250 mL/min, the PQ clearance was greater in HP than in HD during the first 90 minutes: 215 versus 175 mL/min at 30 minutes, 213 versus 201 mL/min at 60 minutes, and 199 versus 179 mL/min at 90 minutes. The clearance in HP decreased rapidly after two hours. By the end of the dialysis, however, the final concentration in container decreased to 5.7 mg/mL in HD and 1.5 mg/mL in HP, which implied that although HD was cleared more effectively during the later stages, the overall elimination was greater in HP. Following this preliminary investigation, we performed HP on all the patients in order to assess the extracorporeal elimination.

One hundred and five patients who had swallowed one to three mouthfuls of PQ (24.5% w/v) solution were subjected to the in vivo study. The reduction rate of PQ was checked out by measuring the PQ concentration in plasma before and after four hours of HP. Seeing the reduction rate was significantly higher in the survivors group than in the nonsurvivors group (80.39 ± 19.9 versus 67.29 ± 19.2%, P <0.01), we concluded that adequate HP appears to be an indispensable treatment for patients with acute PQ poisoning.

To Explore the Characteristics of Fatality in Children Poisoned by Paraquat – with Analysis of 146 Cases

Purpose

The incidence of paraquat (PQ) poisoning in China is increasing, so it is important to identify the characteristics of fatalities in children with acute PQ poisoning in order to prevent and treat future cases.

Methods

A prospective study that enrolled 146 children with PQ poisoning was performed. A novel evaluation system called the score of lethal factors for PQ poisoning (SLFPP) was established, including 1 contributing factor and 4 weakening factors. Comparisons with the Pediatric Logistic Organ Dysfunction (PELOD) score, the Poisoning Severity Score (PSS) in admission and the SLFPP were made to determine their values for prognosis.

Results

Younger patients (71/146, <10 years) had accidental exposure to PQ (64/71, 90.14%), whereas older patients (75/146, ≥10 years) had ingested PQ intentionally (46/75, 61.33%) (p<0.01); 21/146 (14.38%) died of PQ poisoning. Of these 21 children, 20 committed suicide with ages ≥10 years. Significant differences (p<0.01) were found between nonsurvivors and survivors with regard to the Pediatric Logistic Organ Dysfunction (PELOD) scores (19.76 ± 18.44 vs. 4.17 ± 5.98), PSS in admission (2.48 ± 0.60 vs. 1.43 ± 0.59), the SLFPP (10.40 ± 1.07 vs. 3.60 ± 1.89). In PELOD score and PSS in admission, there were relative large overlaps in scores between nonsurvivors and survivors. But for SLFPP, there were smaller overlaps.

Conclusions

Deliberate ingestion of PQ to commit suicide occurred mainly in older children (≥10 years), while accidental exposure to PQ occurred mainly in younger children (<10 years). Owing to small overlaps, the SLFPP may exceed PELOD and PSS in predicting the prognosis of PQ poisoning, but the SLFPP scores still require further clinical validation.

Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: 'Swimming between the flags'

The purpose of the Thoracic Society of Australia and New Zealand guidelines is to provide simple, practical evidence-based recommendations for the acute use of oxygen in adults in clinical practice. The intended users are all health professionals responsible for the administration and/or monitoring of oxygen therapy in the management of acute medical patients in the community and hospital settings (excluding perioperative and intensive care patients), those responsible for the training of such health professionals, and both public and private health care organizations that deliver oxygen therapy.

Successful extracorporeal membrane oxygenation therapy as a bridge to sequential bilateral lung transplantation for a patient after severe paraquat poisoning

CONTEXT

Paraquat is a widely used herbicide that can cause severe to fatal poisoning in humans. The irreversible and rapid progression of pulmonary fibrosis associated with respiratory failure is the main cause of death in the later stages of poisoning. There are infrequent reports of successful lung transplants for cases of severe paraquat poisoning. We expect that this successful case will provide a reference for other patients in similar circumstances.

CASE DETAILS

A 24-year-old female was sent to the hospital approximately 2 hours after ingesting 50 ml of paraquat. She experienced rapidly aggravated pulmonary fibrosis and severe respiratory failure. On the 34th day after ingestion, she underwent intubation and invasive mechanical ventilation. The patient was evaluated for lung transplantation, and veno-venous extracorporeal membrane oxygenation (ECMO) was established as a bridge to lung transplantation on the 44th day. On the 56th day, she successfully underwent a bilateral sequential lung transplantation. Through respiratory and physical rehabilitation and nutrition support, the patient was weaned from mechanical ventilation and extubated on the 66th day. On the 80th day, she was discharged. During the 1-year follow-up, the patient was found to be in good condition, and her pulmonary function improved gradually.

CONCLUSION

We suggest that lung transplantation may be an effective treatment in the end stages of paraquat-induced pulmonary fibrosis and consequential respiratory failure. For patients experiencing a rapid progression to a critical condition in whom lung transplantation cannot be performed immediately (e.g., while awaiting a viable donor or toxicant clearance), ECMO should be a viable bridge to lung transplantation.

External validation of the prognostic index in acute paraquat poisoning

OBJECTIVE

Some studies have evaluated the prognostic indicators associated with acute paraquat (PQ) poisoning. In this study, we externally validated the Yamaguchi index, which showed a good prognostic relevance in predicting the outcome of PQ poisoning.

METHODS

A retrospective analysis of 297 patients was performed. The Yamaguchi index was calculated using the following equation: Eq1 = (K(+) × HCO3(-))/(Creatinine × 0.088)(mEq/L) against time from PQ ingestion (T). The patients were divided into three groups: group A: Eq1 > 1500 - 399 × log T, group B: 930 - 399 × log T < Eq1 ≤ 1500 - 399 × log T, and group C: Eq1 ≤ 930 - 399 × log T).

RESULTS

The overall mortality rate was 65.3% (194 of 297). The mortality rates of the three groups stratified by the Yamaguchi index were 7.1% (2 of 28), 22.4% (15 of 67), and 87.6% (177 of 202). The area under the receiver-operating characteristic curve for predicting mortality from the external validation of the Yamaguchi index was 0.842 (95% confidence interval: 0.795-0.882).

CONCLUSION

The Yamaguchi index is a reliable prognostic factor and could be helpful in predicting mortality due to PQ poisoning.

Effects of noninvasive positive pressure ventilation on oxygenation status and prognosis in patients with acute paraquat-induced lung injury

PURPOSE

The aim of this study was to evaluate the effects of noninvasive positive pressure ventilation (NIPPV) on oxygenation status and prognosis in patients with acute lung injury induced by paraquat (PQ) poisoning.

METHODS

Patients with acute PQ-induced lung injury treated with NIPPV were admitted to an emergency intensive care unit. Changes in oxygenation status (respiratory rate and the partial pressure of alveolar O2 and CO2 [PaO2 and PaCO2, respectively]) after initial NIPPV were observed. Differences in inspiratory pressure (PI) between nonsurvivors and survivors were compared. The relationship between PI and the prognosis of patients with acute PQ-induced lung injury was evaluated.

FINDINGS

A total of 86 patients (47 women, 39 men; mean age, 33.5 [24.5] years [range, 22-61 years]) were included. There were significant differences in respiratory rate, PaO2, and PaCO2 from before to after initial NIPPV (respiratory rate, 35 [14] vs 26 [16] min(-1) [P = 0.037]; PaO2, 61.8 [19.6] vs 73.5 [26.8] mm Hg [P = 0.046]; and PaCO2, 27.7 [16.4] vs 34.6 [19.2] mm Hg [P = 0.039]). The overall mortality rate was 75.6% (65/86) during a 28-day follow-up period. We observed a significant difference in initial PI (PIinit) between nonsurvivors and survivors (8.2 [4.3] vs 6.6 [3.8] cm H2O; P = 0.043). Furthermore, nonsurvivors had a greater maximal PI (PImax) than did survivors (21.6 [9.8] vs 15.4 [8.5] cm H2O; P = 0.022). Correlation analysis revealed that both PIinit and PImax were associated with a poor prognosis in patients with acute PQ-induced lung injury (PIinit, r = -0.29 [P = 0.038]; PImax, r = -0.31 [P = 0.042]).

IMPLICATIONS

NIPPV may effectively improve oxygenation status in patients with acute PQ-induced lung injury, thereby relieving dyspnea and promoting the recovery of pulmonary function. PIinit and PImax may be important determinants of prognosis in acute PQ-induced lung injury. These findings need further verification in a large-scale, multicenter, randomized controlled study that combines other factors with a relatively long-term follow-up.

Comparison between kidney and continuous plasma perfusion for paraquat elimination

BACKGROUND

Thousands of paraquat (PQ)-poisoned patients continue to die. Plasma perfusion (PP) has recently been incorporated as a method of clinical detoxification. The purpose of this study was to estimate the PQ clearance of PP and observe the effect of PP on PQ concentration in the blood of patients with acute PQ poisoning.

METHODS

Twenty one PQ-poisoned patients admitted to our poisoning center within 24 hours after the ingestion were prospectively enrolled. Continuous plasma perfusion was performed. Urinary PQ and plasma PQ concentration level at inlet/outlet of the cartridge were obtained right before and 1.5 hours after the start of each perfusion session for the calculation of renal and plasma PQ excretion.

RESULTS

In all 8 rounds (108 sessions) of PP on the 21 patients, PQ clearance rate (mL/min) by PP was always found to be higher than the renal value: (1st 11.14 ± 6.13 versus 6.53 ± 1.46; 2nd 18.36 ± 11.32 versus 6.23 ± 1.51; 3rd 16.13 ± 10.05 versus 4.01 ± 0.93; 4th 12.86 [6.72, 17.47] versus 2.42 [0.65, 4.20]; 5th 14.12 [10.48, 35.20] versus 1.77 [0.63, 2.91]; 6th 16.47 [11.82; 20.69] versus 1.70 [0.23, 3.18]; 7th 13.33 [9.71, 18.75] versus 1.10 [0.14, 2.99]; 8th 11.27 [9.21, 16.02] versus 1.10 [0.09, 2.79], P < 0.05). The survivors showed a higher plasma PQ reduction rate (mg L hour) than the nonsurvivors (0.57 ± 0.03 versus 0.47 ± 0.06, P < 0.05).

CONCLUSIONS

Our data show that PP therapies help in the clearance of PQ and may prove a promising therapeutic tool in patients with acute PQ intoxication.

QTc prolongation as a useful prognostic factor in acute paraquat poisoning

BACKGROUND

Acute paraquat poisoning has a high mortality rate. Several prognostic factors have been proposed to predict the mortality risk of paraquat-poisoned patients. However, these prognostic factors are complex and some require a laboratory. Corrected QT (QTc) has been used as a prognostic factor in several clinical conditions, such as acute organophosphate poisoning. In addition, the measurement can be obtained in a reasonable amount of time.

STUDY OBJECTIVES

This study's objective was to investigate whether QTc can predict mortality in paraquat-poisoned patients.

METHODS

This was a retrospective study. Potential prognostic factors such as QTc, vital signs at admission, and certain biochemistry variables were analyzed with Cox regression analyses for their ability to predict a patient's survival from paraquat poisoning.

RESULTS

Sixty acute paraquat-poisoned patients were admitted to the emergency department during the study period. The QTc of the survival group ranged from 0.35 to 0.48 s, whereas the nonsurvivor group ranged from 0.32 to 0.63 s. The nonsurvivor group contained a higher percentage of patients with QTc prolongation (≥0.45 s) compared with the survivor group (p = 0.04). The hazard ratio of QTc prolongation for a patient's death was found to be 2.47 (95% confidence interval [CI] 1.68-5.67) in patients with a lower potassium level (<3.2 mEq/L) and 3.71 (95% CI 1.53-8.97) in patients with a higher potassium level (≥3.2 mEq/L). In addition, hyperdynamic circulation was observed upon admission of these poisoned patients.

CONCLUSION

QTc prolongation is a useful prognostic factor for predicting death in acute paraquat-poisoned patients. Cardiovascular collapse may occur in some paraquat-poisoned patients. Physicians can use QTc as an indicator of a patient's severity of poisoning and mortality risk.

Paraquat poisoning: A case report and review of literature

Paraquat (1, r-dimethyl-4,4’-bipyridium dichloride), a brown syrupy liquid is an effective herbicide that has low chronic toxicity because of its rapid deactivation on contact with soil. A high dose of paraquat or severe poisoning has a poor prognosis. At present there is no specific antidote to paraquat poisoning, hence the need to focus on prevention and in case of exposure or ingestion, aggressive decontamination to prevent further absorption. Although uncommon, paraquat ingestion can lead to severe and often fatal toxicity. However, despite its widespread availability, reports of this herbicide poisoning in India are uncommon.

Diphenyl diselenide prevents hepatic alterations induced by paraquat in rats

This study aimed to investigate the beneficial effect of diphenyl diselenide (PhSe)₂ on paraquat (PQ) induced alterations in rats liver. Adult male Wistar rats received (PhSe)₂ at 10 mg kg(-1), by oral administration (p.o.), during five consecutive days. Twenty-four hours after the last (PhSe)₂ dose, rats received PQ at 15 mg kg(-1), in a single intraperitoneally injection (i.p.). Seventy-two hours after PQ exposure, animals were sacrificed by decapitation for blood and liver samples obtainment. Histological alterations induced by PQ exposure, such as inflammatory cells infiltration and edema, were prevented by (PhSe)₂ administration. Moreover, (PhSe)₂ prevented hepatic lipid peroxidation (LPO) induced by PQ and was effective in reducing the myeloperoxidase (MPO) activity in liver, which was enhanced by PQ exposure. (PhSe)₂ also was effective in protecting against the reduction in ascorbic acid and non-protein thiols (NPSH) levels induced by PQ. The inhibition of glutathione S-transferase (GST) activity, in rats exposed to PQ, was normalized by (PhSe)₂ pre-treatment, whereas the inhibition of catalase (CAT) activity was not prevented by (PhSe)₂. The serum alkaline phosphatase (ALP) inhibition, induced by PQ administration, was also prevented by (PhSe)₂ pre-treatment. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were not modified by PQ and/or (PhSe)₂ administration. Therefore, (PhSe)₂ pre-treatment was effective in protecting against the hepatic alterations induced by PQ in rats. This protective effect can involve the antioxidant and anti-inflammatory properties of (PhSe)₂.

Paraquat poisoning by skin absorption: Two case reports and a literature review

The present report describes two cases of paraquat poisoning by skin absorption. The cases involved contractual workers who were spraying paraquat in an orchard. Whilst spraying, some solution adhered to their skin. The skin developed erythema followed by blistering and hemorrhaging hemorrhagic diabrosis. Six days later the patients were admitted to the Department of Poisoning and Occupational Disease, Qilu Hospital of Shandong University (Jinan, China) with 3 and 2% total body surface area (TBSA) burns, respectively. Surgical debridement was performed and immunosuppressants were administered during the patients’ treatment. The patients were treated successfully and had made a complete recovery following 21 days. From these cases it was examined how paraquat may cause skin injuries and occasionally poisoning. To the best of our knowledge, cases of paraquat poisoning are rare in China. A review of the relevant literature was performed.

A bioconjugated design for amino acid-modified mesoporous silicas as effective adsorbents for toxic chemicals

A general synthetic method for functionalization of mesoporous silica with amino acid has been developed. The carboxylic acid functionalized SBA-15 was conjugated with l-phenylalanine (Phe) and l-tryptophan (Trp) to obtain nontoxic amino acid-conjugated functionalized mesoporous silica materials. The materials were used as adsorbents for the removal of the herbicide Paraquat (PQ) and its analog, ethyl viologen dibromide (EVB) from aqueous solutions. In comparison to the commercially available activated carbon adsorbents, the silica-based adsorbents prepared in this study exhibited relatively higher PQ removal efficiency in aqueous solutions at room temperature and pH 7.0. The silica-based adsorbents, pendant with amino acid moieties exhibited greater adsorption capacities toward PQ and EVB than the analogs but without the amino acid moiety, suggesting that there is a benefit for the enhanced π-π interaction between the aromatic groups of the conjugated amino acid moieties and the adsorbate. This bioconjugated method developed here provides a promising new tool to synthesize new materials for detoxification of herbicides in clinical trials.

Tissue concentration of paraquat on day 32 after intoxication and failed bridge to transplantation by extracorporeal membrane oxygenation therapy

Background

Paraquat is a highly toxic herbicide, which not only leads to acute organ damage, but also to pulmonary fibrosis. There are only anecdotal reports of rescue lung transplantation, as paraquat is stored and only slowly released from different tissues. Bridging the time to complete depletion of paraquat from the body could render this exceptional therapy strategy possible, but not much is known on the time interval after which transplantation can safely be performed.

Case presentation

We report on a case of accidental paraquat poisoning in a 23 years old Caucasian man, who developed respiratory failure due to pulmonary fibrosis. The patient was listed for high urgency lung transplantion, and extracorporeal membrane oxygenation was implemented to bridge the time to transplantation. The patient died 32 days after paraquat ingestion, before a suitable donor organ was found. In postmortem tissue specimen, no paraquat was detectable anymore.

Conclusion

This case report indicates that complete elimination of paraquat after oral ingestion of a lethal dose is achievable. The determined time frame for this complete elimination might be relevant for patients, in which lung transplantation is considered.

Prediction of prognosis in acute paraquat poisoning using severity scoring system in emergency department

OBJECTIVE

The aim of this study was to validate and compare the performance of serum paraquat level, severity index of paraquat poisoning (SIPP), Acute Physiology And Chronic Health Evaluation II (APACHE II), modified Simplified Acute Physiology Score II (MSAPS II), and modified Expanded Simplified Acute Physiology Score II (MSAPS IIe) calculated immediately after arrival on emergency department (ED) for assessing the mortality of acute paraquat poisoning.

METHODS

A retrospective study design was employed with the main outcome measure being mortality from year 2001 to 2010. MSAPS II and MSAPS IIe were employed in that assessment of the 24-hour urine output were not included. The performance of APACHE II, MSAPS II, MSAPS IIe, serum paraquat level and SIPP for prediction of mortality in acute paraquat poisoning were compared.

RESULTS

A total of 102 patients were enrolled in the study. The area under the ROC curve for APACHE II (0.800) was statistically lower than those for MSAPS II, MSAPS IIe, SIPP and serum paraquat (0.879, 0.893, 0.924,and 0.951, respectively). The Hosmer-Lemeshow goodness-of-fit test C statistic revealed that APACHE II, MSAPS II, MSAPS IIe and serum paraquat level showed good calibrations (chi-square 8.477 and p = 0.388, chi-square 4.614 and p = 0.798, chi-squared 5.301 and p = 0.725, chi-squared 1.009 and p = 0.985 respectively), but poor calibration for SIPP (chi-square 21.293 and p = 0.006).

CONCLUSION

Serum paraquat level is still the most reliable prognosis factor in acute paraquat poisoning. But MSAPS II or MSAPS IIe calculated immediately after arrival on ED may be helpful to predict mortality in acute paraquat poisoning especially when hospital has no facility to measure serum paraquat level.

The role of pentraxin-3 as a prognostic biomarker in paraquat poisoning

Paraquat poisoning has been a public health problem in both the developing and developed countries. Pentraxin 3 is a member of the pentraxin family which is expressed as part of the acute-phase response that begins after injury, trauma, and infection. The aim of our study is to determine whether PTX3 levels can be a significant marker of pulmonary fibrosis and outcome of survival in paraquat poisoning. To measure the plasma paraquat level, we collected serum of the patients immediately after admission. EDTA plasma samples for checking the plasma PTX3 concentration were taken before and after the 1st hemoperfusion and after the 2nd hemoperfusion therapy. PTX3 concentrations in EDTA plasma were determined using a commercial solid-phase enzyme-linked immunosorbent assay (ELISA). Plasma paraquat concentration was higher in survivors than in non-survivors (p<0.05). Maximal plasma PTX3 level was significantly higher in the pulmonary fibrosis group, and plasma PTX3 was significantly increased throughout hemoperfusion therapy (p<0.01). Moreover, increase in PTX3 was greater in non-survivors than survivors (p<0.05). Our results show that PTX3 is a useful biomarker of severity and outcome predictor in paraquat poisoning.

Efficacy of vitamin C against liver and kidney damage induced by paraquat toxicity

Paraquat has been demonstrated to be a highly toxic compound for humans and animals and many cases of acute poisoning and death have been reported over the past few decades. The current experiment aimed to examine if vitamin C (ascorbic acid) alleviates the morphological changes induced by paraquat (PQ) administration in the liver and kidney of male albino rats. Male adult rats received paraquat (PQ) (1.5 mg/kg body weight) daily for three weeks. Vitamin C (VC) at a dose of 20 mg/kg body weight was given concomitantly with PQ to rats. Animals were divided into three groups in this experiment (control, PQ and PQ+VC). The morphopathological manifestations were investigated in tissues from liver and kidney. As expected, PQ administration induced marked changes in the morphological structure of the liver and kidney in PQ demonstrated animals. Importantly, vitamin C administration restored PQ-induced changes in the studied organs. Vitamin C administration attenuated the morphological damages induced by PQ in the liver and kidney of experimental animals. Our results suggest an antitoxic effect of vitamin C against paraquat.

The efficacy of high doses of vitamin C in patients with paraquat poisoning

Paraquat (PQ) poisoning is an extremely difficult condition to manage clinically because of the lack of effective treatments. The purpose of this study was to assess the effect of high doses of vitamin C in combination with anti-inflammatory and immunosuppressant therapy in patients with PQ poisoning. The medical records of 134 patients who presented to the emergency department within 24 hours after PQ poisoning were reviewed retrospectively. The 57 patients presented between January 2004 and September 2005 were group 1; they received pulse therapy, which included cyclophosphamide and methylprednisolone, followed by the administration of dexamethasone over 2 weeks. The 77 patients that presented between October 2005 and January 2008 were group 2; they received the above-mentioned therapy and high-dose vitamin C for 2 weeks. There was no difference in the distribution of baseline variables between the 2 groups. However, group 2 showed a significant reduction in acute kidney injury related to PQ. Furthermore, a multivariate logistic regression analysis showed that the addition of vitamin C to the treatment was significantly associated with an increased survival of the patients. Larger trials will be needed to verify the effect of high-dose vitamin C on survival in patients with PQ poisoning.

Postmortem analyses unveil the poor efficacy of decontamination, anti-inflammatory and immunosuppressive therapies in paraquat human intoxications

Background

Fatalities resulting from paraquat (PQ) self-poisonings represent a major burden of this herbicide. Specific therapeutic approaches have been followed to interrupt its toxic pathway, namely decontamination measures to prevent PQ absorption and to increase its excretion from organism, as well as the administration of anti-inflammatory and immunosuppressive drugs. Until now, none of the postmortem studies resulting from human PQ poisonings have assessed the relationship of these therapeutic measures with PQ toxicokinetics and related histopathological lesions, these being the aims of the present study.

Methodology/Principal Findings

For that purpose, during 2008, we collected human fluids and tissues from five forensic autopsies following fatal PQ poisonings. PQ levels were measured by gas chromatography-ion trap mass spectrometry. Structural inflammatory lesions were evaluated by histological and immunohistochemistry analysis. The samples of cardiac blood, urine, gastric and duodenal wall, liver, lung, kidney, heart and diaphragm, showed quantifiable levels of PQ even at 6 days post-intoxication. Structural analysis showed diffused necrotic areas, intense macrophage activation and leukocyte infiltration in all analyzed tissues. By immunohistochemistry it was possible to observe a strong nuclear factor kappa-B (NF-κB) activation and excessive collagen deposition.

Conclusions/Significance

Considering the observed PQ levels in all analyzed tissues and the expressive inflammatory reaction that ultimately leads to fibrosis, we conclude that the therapeutic protocol usually performed needs to be reviewed, in order to increase the efficacy of PQ elimination from the body as well as to diminish the inflammatory process.

Delayed immunosuppressive treatment in life-threatening paraquat ingestion: a case report

INTRODUCTION

Combined glucocorticoids and cyclophosphamide pulse therapy showed promising results in moderate-to-severe paraquat poisonings to reduce life-threatening respiratory complications. Its benefit has been observed when given early in the course of poisoning; however, whether its delayed administration remains beneficial is unknown.

CASE REPORT

We describe a 23-year-old male who ingested 70 mL of a commercialized concentrate formulation with 20% weight/volume paraquat in a suicide attempt. Within 24 hours from paraquat ingestion, he presented most of the indicators of poor outcome, including gastritis, early renal dysfunction, dark blue urine colorimetric dithionite test, and marked plasma paraquat concentrations (0.56 microg/mL at 13 hours, and 0.41 microg/mL at 24 hours after ingestion). The patient received early gastrointestinal decontamination and aggressive supportive treatments. However, due to a rapidly progressive severe pulmonary infection, glucocorticoids and cyclophosphamide were delayed until day 14. Interestingly, our patient survived with mild respiratory sequelae despite poor initial prognosis.

DISCUSSION

This observation suggests the potential benefit of immunosuppressive pulse therapy, even if administered 14 days after paraquat ingestion, and highlights the role of paraquat-induced alveolitis in the development of fibrosis.

CONCLUSION

Combined glucocorticoids and cyclophosphamide should be considered in moderate-to-severe paraquat poisonings, even if delayed.

A Fatal Case of Paraquat Poisoning Following Minimal Dermal Exposure

Paraquat is a pesticide widely used in agriculture. Numerous cases of paraquat intoxication have been reported either accidentally or intentionally as a suicidal attempt. The most severe cases of paraquat poisoning refer to oral ingestion. Complications include respiratory, hepatic, and renal failure, and are usually fatal. Dermal exposure is less frequent and rarely fatal. This article reports a case of an 81-year-old man with minimal skin burn after accidental paraquat exposure. The patient developed acute renal and respiratory failure and, despite aggressive treatment with hemodialysis, hemoperfusion, and mechanical ventilation, died two days later.

The level and clinical significance of pancreatic enzymes in survivors of acute paraquat poisoning

INTRODUCTION

Acute paraquat poisoning is often fatal. When ingested, paraquat affects multiple organs including the lung, gastrointestinal tract, pancreas, kidney, heart, and central nervous system. Our center previously found that initial pancreatic function was related to the prognosis of patients with acute paraquat poisoning. However, pancreatic injury after paraquat intoxication has been incompletely studied.

METHODS

This study analyzed the clinical outcome and extent of pancreatic injury in 34 survivors of acute paraquat poisoning. Paraquat exposure was assessed based on a quantitative measure of the plasma level of paraquat by high-performance liquid chromatography. The subsequent variations in the level of pancreatic enzymes, clinical symptoms, and abdominal computed tomography were obtained. Outcomes after acute paraquat poisoning were categorized as pancreatic enzyme elevation group (elevation group: amylase >160 IU/L and lipase >100 IU/L) and nonelevation group.

RESULTS

Pancreatic enzyme elevations occurred in seven cases (20.6%), and the level of pancreatic enzymes peaked at day 7. The elevation in pancreatic enzymes after paraquat ingestion was positively correlated with the plasma paraquat level (p < 0.05 at days 4 and 7). Creatinine was higher in the elevation group. Abdominal computed tomography of the seven cases showed no evidence of pancreatitis, and significant abdominal pain was not observed.

DISCUSSION

Pancreatic enzyme elevation reflects the systemic toxicity and multiorgan involvement following acute paraquat poisoning.

CONCLUSIONS

Pancreatic injury was subtle and the elevation of pancreatic enzymes in survivors is clinically benign.

Marked recovery from paraquat-induced lung injury during long-term follow-up

BACKGROUND/AIMS

Paraquat-induced lung injury has been considered a progressive and irreversible disease. The purpose of this study was to report the long-term evolution of lung lesions in eight survivors with significant paraquat-induced lung injuries who could be followed-up for longer than 6 months.

METHODS

We retrospectively examined high-resolution computed tomography and pulmonary function test of eight survivors with significant paraquat-induced lung injurys.

RESULTS

High-resolution computed tomography revealed a predominant pattern of irregularly shaped consolidation with traction bronchiectasis at 1-2 months after paraquat poisoning, a mixed pattern of irregularly shaped consolidation and ground-glass opacity at 3-12 months, and a mixed pattern of consolidation, ground-glass opacity, and honeycombing at 1-2 years. At 3-12 months after paraquat ingestion, the areas of consolidation had markedly decreased and the decreased lung volume had returned to normal. At 1-2 years after paraquat poisoning, the cystic changes had disappeared. At 2-3 years after paraquat poisoning, the decrease in forced vital capacity had greatly improved to the normal range.

CONCLUSIONS

Recovery of nearly normal pulmonary structure and function may occur over several years following paraquat poisoning. Pulmonary function (both forced vital capacity and forced expiratory volume in 1 sec) evolved toward normal in the long-term survivors of paraquat poisoning with initial prominent lung injuries.

Comparison between kidney and hemoperfusion for paraquat elimination

The mortality rate of acute paraquat (PQ) poisoning depends on the PQ concentration in the blood. It has been shown that the kidneys eliminate PQ effectively. However, early renal function deterioration is frequently observed in acute PQ intoxication. This study is designed to compare the efficacy of PQ elimination with hemoperfusion (HP) and kidneys, taking into account the functional deterioration of the kidneys. The amount of renal and HP excretion of PQ were measured during the procedure of HP in patients with acute PQ intoxication. The PQ clearance and the actual amount of PQ elimination by the HP cartridge during the HP procedure were 111+/-11 mL/min (range; 13.2-162.2 mL/min) and 251.4+/-506.3 mg (range; 4.6-1,655.7) each. While, the renal clearance and actual amount of renal elimination of PQ was 79.8+/-56.0 mL/min (range; 9.7-177.0) and 75.4+/-73.6 mg (range; 4.9-245.8). As the creatinine clearance decreased, the PQ elimination by HP was as effective as or more effective than the renal elimination. In conclusion, early HP must be provided for life saving treatment in patients with acute PQ intoxication.

A case of paraquat intoxication caused by intravenous injection

Paraquat intoxication is a fatal problem. Most paraquat intoxications happen through oral administration. We report a case of death after intravenous paraquat injection. There is little clinical data on parenteral paraquat exposure, and we describe this case and fatal progression. Toxic symptoms and severe organ function impairment developed soon after injection. Treatment with repeated activated charcoal hemoperfusion with pulse steroids, cyclophosphamide, and antioxidants was attempted. The patient died from multiple organ failure 3 days after intoxication. This case indicates that paraquat intoxication via intravenous injection, even in very small amounts, has an extremely poor prognosis.

Hypokalemia and hypothermia are associated with 30-day mortality in patients with acute paraquat poisoning

BACKGROUND

Clinical predictors associated with acute paraquat (PQ) poisoning have not been systematically studied.

OBJECTIVE

To identify independent predictors of death in patients with acute PQ poisoning.

METHODS

This is a retrospective study executed in the emergency department of a university hospital. One hundred three consecutive patients poisoned with PQ between January 1999 and December 2004 were enrolled. Urine PQ concentration, electrolyte and renal function, detailed history, and Acute Physiology and Chronic Health Evaluation II were extracted from medical records. The outcome measure was 30-day mortality. Multivariate analysis was done by Cox-proportional hazard regression model. Receiver operating characteristics area under the curve was calculated for selected predictors.

RESULTS

The crude 30-day mortality was 67.9% (70 of 103). Independent predictors of death were acute renal failure (hazard ratio, 3.53; 95% confidence interval, 1.97-6.32), hypokalemia (2.07, 1.21-3.51), hypothermia (2.91, 1.67-5.07), suicide (2.11, 1.04-4.29), and self-reported ingested dose (2.06, 1.38-3.06). The receiver operating characteristics area under the curve of serum potassium concentrations, maximal urine PQ concentrations, and Acute Physiology and Chronic Health Evaluation II scores were 0.75 (95% confidence interval, 0.60-0.81), 0.71 (0.66-0.84), and 0.80 (0.71-0.88), respectively. Under the cutoff value of 3.6 mEq/L, hypokalemia had a sensitivity of 75% and specificity of 54% in predicting mortality.

CONCLUSION

The identified risk factors may allow better identification of those at greater mortality risk. Future development of a tailored clinical scoring system incorporating the identified risk factors for acute PQ poisoning may be of great help.

Paraquat poisonings: mechanisms of lung toxicity, clinical features, and treatment

Paraquat dichloride (methyl viologen; PQ) is an effective and widely used herbicide that has a proven safety record when appropriately applied to eliminate weeds. However, over the last decades, there have been numerous fatalities, mainly caused by accidental or voluntary ingestion. PQ poisoning is an extremely frustrating condition to manage clinically, due to the elevated morbidity and mortality observed so far and due to the lack of effective treatments to be used in humans. PQ mainly accumulates in the lung (pulmonary concentrations can be 6 to 10 times higher than those in the plasma), where it is retained even when blood levels start to decrease. The pulmonary effects can be explained by the participation of the polyamine transport system abundantly expressed in the membrane of alveolar cells type I, II, and Clara cells. Further downstream at the toxicodynamic level, the main molecular mechanism of PQ toxicity is based on redox cycling and intracellular oxidative stress generation. With this review we aimed to collect and describe the most pertinent and significant findings published in established scientific publications since the discovery of PQ, focusing on the most recent developments related to PQ lung toxicity and their relevance to the treatment of human poisonings. Considerable space is also dedicated to techniques for prognosis prediction, since these could allow development of rigorous clinical protocols that may produce comparable data for the evaluation of proposed therapies.

Improvement in survival after paraquat ingestion following introduction of a new formulation in Sri Lanka

BACKGROUND

Pesticide ingestion is a common method of self-harm in the rural developing world. In an attempt to reduce the high case fatality seen with the herbicide paraquat, a novel formulation (INTEON) has been developed containing an increased emetic concentration, a purgative, and an alginate that forms a gel under the acid conditions of the stomach, potentially slowing the absorption of paraquat and giving the emetic more time to be effective. We compared the outcome of paraquat self-poisoning with the standard formulation against the new INTEON formulation following its introduction into Sri Lanka.

METHODS AND FINDINGS

Clinical data were prospectively collected on 586 patients with paraquat ingestion presenting to nine large hospitals across Sri Lanka with survival to 3 mo as the primary outcome. The identity of the formulation ingested after October 2004 was confirmed by assay of blood or urine samples for a marker compound present in INTEON. The proportion of known survivors increased from 76/297 with the standard formulation to 103/289 with INTEON ingestion, and estimated 3-mo survival improved from 27.1% to 36.7% (difference 9.5%; 95% confidence interval [CI] 2.0%-17.1%; p = 0.002, log rank test). Cox proportional hazards regression analyses showed an approximately 2-fold reduction in toxicity for INTEON compared to standard formulation. A higher proportion of patients ingesting INTEON vomited within 15 min (38% with the original formulation to 55% with INTEON, p < 0.001). Median survival time increased from 2.3 d (95% CI 1.2-3.4 d) with the standard formulation to 6.9 d (95% CI 3.3-10.7 d) with INTEON ingestion (p = 0.002, log rank test); however, in patients who did not survive there was a comparatively smaller increase in median time to death from 0.9 d (interquartile range [IQR] 0.5-3.4) to 1.5 d (IQR 0.5-5.5); p = 0.02.

CONCLUSIONS

The survey has shown that INTEON technology significantly reduces the mortality of patients following paraquat ingestion and increases survival time, most likely by reducing absorption.