Recovery of respiratory function in survivors with paraquat intoxication

Monocytes as an Early Predictor for Patients with Acute Paraquat Poisoning: A Retrospective Analysis

BACKGROUND

The predictive values of monocytes in the prognosis of patients with acute paraquat (PQ) poisoning are unclear. This retrospective study investigated the predictive values of monocytes in the prognosis of patients with acute PQ poisoning.

METHODS

Adult patients who suffered from acute PQ poisoning in the emergency care unit of Cangzhou Central Hospital from May 2012 to December 2018 were enrolled. The patients were divided into groups, namely, survival and nonsurvival, according to a 90-day prognosis. Moreover, correlation, logistic regression, receiver-operator characteristic (ROC), and Kaplan-Meier curve analyses were applied to evaluate the monocyte values used to predict the prognosis of patients with acute PQ poisoning.

RESULT

Among the 109 patients, 45 survived within 90 days after the poisoning, resulting in a 41.28% survival rate. The monocyte count of the nonsurvivors was significantly higher than that of the survivors (P< 0.001). Correlation analysis showed that monocyte count positively correlated with plasma PQ concentration (r= 0.413; P< 0.001) and negatively correlated with survival time (r= 0.512; P< 0.001) and 90-day survival (r= 0.503; P< 0.001). Logistic regression analysis showed that elevated monocytes were the independent risk factors for the 90-day survival. The area under the ROC curve of the monocyte count used to predict the 90-day survival was 0.826 (95% CI: 0.751-0.904), the optimal cut-off was 0.51×109/L, sensitivity was 73.4%, and specificity was 86.7%.

CONCLUSION

This study demonstrated that elevated monocyte count is a useful early predictor of 90-day survival in patients with acute PQ poisoning. However, further studies are warranted to draw firm conclusions.

Metabolitic profiling of amino acids in paraquat-induced acute kidney injury

BACKGROUND

The herbicide paraquat (1, 1'-dimethyl-4, 4'-bipyridylium dichloride; PQ) is a poison well-known to cause delayed mortality due to acute kidney injuries (AKI). This study examines the changes in serum amino acids (AAs) metabolite profiles as surrogate markers of renal cell metabolism and function after paraquat poisoning.

METHODS

To identify the metabolic profiling of free serum AAs and its metabolites, serum from 40 paraquat-poisoned patients with or without AKI is collected. LC-MS/GC-MS is performed to analyze AA molecules. A Cox proportional hazard model was used to assess for incidence of AKI. Receiver operating characteristic (ROC) curve is applied to evaluate AKI occurrence and prognosis.

RESULTS

A total of 102 serum AAs and its metabolites were identified. Compared with non-AKI patients, 37 varied significantly in AKI patients. The univariate Cox proportional hazard model analysis revealed that the estimated PQ amount, plasma PQ concentration, urine PQ concentration, APACHE, SOFA scores and 16 amino acids correlated with the incidence of AKI. Further analyses revealed that 3-methylglutarylcarnitine, 1-methylimidazoleacetate, and urea showed higher cumulative hazard ratios for the occurrence of AKI during follow-up (P < 0.05). The area under the curve (AUC) of 3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were 0.917, 0.857, 0.872, respectively.

CONCLUSION

3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were associated with AKI in patients with paraquat intoxication.

Patients with mild paraquat poisoning treated with prolonged low-dose methylprednisolone have better lung function: A retrospective analysis

Lung dysfunction is an important characteristic of injury induced by paraquat (PQ). This study aimed to evaluate the effects of prolonged low-dose methylprednisolone (MP) treatment on lung function in patients with mild PQ poisoning. We analyzed the results of lung function testing in all patients with mild PQ poisoning admitted to Cangzhou Central Hospital between January 2012 and August 2017. Patients were grouped according to short-term treatment (3 mg/kg/day MP for 3 days) or prolonged treatment (3 mg/kg/day MP for 3 days, followed by dosage reduction by half every 3 days, with treatment terminated when a dosage of 0.375 mg/kg/day was reached). Lung function was evaluated at 2 to 3 months after PQ exposure. The forced expiratory volume in 1 second (85.72 ± 4.93% vs 78.41 ± 4.58%; P < .001), forced vital capacity (81.98 ± 4.93% vs 77.85 ± 4.37%; P < .001), and diffusing capacity (84.27 ± 5.16% vs 76.21 ± 3.71%; P < .001) in the prolonged low-dose MP group were improved compared with those in the short-term MP group. Patients with mild PQ poisoning treated with prolonged low-dose MP had better lung function 2 to 3 months after PQ poisoning.

Point-of-care testing in the early diagnosis of acute pesticide intoxication: The example of paraquat

Acute pesticide intoxication is a common method of suicide globally. This article reviews current diagnostic methods and makes suggestions for future development. In the case of paraquat intoxication, it is characterized by multi-organ failure, causing substantial mortality and morbidity. Early diagnosis may save the life of a paraquat intoxication patient. Conventional paraquat intoxication diagnostic methods, such as symptom review and urine sodium dithionite assay, are time-consuming and impractical in resource-scarce areas where most intoxication cases occur. Several experimental and clinical studies have shown the potential of portable Surface Enhanced Raman Scattering (SERS), paper-based devices, and machine learning for paraquat intoxication diagnosis. Portable SERS and new SERS substrates maintain the sensitivity of SERS while being less costly and more convenient than conventional SERS. Paper-based devices provide the advantages of price and portability. Machine learning algorithms can be implemented as a mobile phone application and facilitate diagnosis in resource-limited areas. Although these methods have not yet met all features of an ideal diagnostic method, the combination and development of these methods offer much promise.

Predictors of acute kidney injury after paraquat intoxication

Paraquat intoxication is characterized by multi-organ failure, causing substantial mortality and morbidity. Many paraquat patients experience acute kidney injury (AKI), sometimes requiring hemodialysis. We observed 222 paraquat-intoxicated patients between 2000 and 2012, and divided them into AKI (n = 103) and non-AKI (n = 119) groups. The mortality rate was higher for AKI than non-AKI patients (70.1% vs. 40.0%, P < 0.001). Patients with AKI had a longer time to hospital arrival (P = 0.003), lower PaO₂ (P = 0.006) and higher alveolar-arterial O₂ difference (P < 0.001) 48 h after admission, higher sequential organ failure assessment 48-h score (P < 0.001), higher severity index of paraquat poisoning (SIPP) score (P = 0.016), lower PaCO₂ at admission (P = 0.031), higher PaO₂ at admission (P = 0.015), lower nadir PaCO₂ (P = 0.001) and lower nadir HCO₃ (P = 0.004) than non-AKI patients. Multivariate logistic regression indicated that acute hepatitis (P < 0.001), a longer time to hospital arrival (P < 0.001), higher SIPP score (P = 0.026) and higher PaO₂ at admission (P = 0.014) were predictors of AKI. The area under the receiver operating characteristic curve confirmed that an Acute Kidney Injury Network 48-hour score ≥ 2 predicted AKI necessitating hemodialysis with a sensitivity of 0.6 and specificity of 0.832. AKI is common (46.4%) following paraquat ingestion, and acute hepatitis, the time to hospital arrival, SIPP score and PaO₂ at admission were powerful predictors of AKI. Larger studies with longer follow-up durations are warranted.

Therapeutic effects of smecta or smectite powder on rats with paraquat toxication

BACKGROUND:

The plasma concentration of paraquat is closely related to the prognosis of patients with paraquat toxication, and the most common cause of death from paraquat poisoning is multiple organ failure (MOF). This study aimed to evaluate therapeutic effect of smecta on the plasma concentrations of paraquat and multi-organ injury induced by paraquat intoxication in rats.

METHODS:

A total of 76 healthy adult SD rats were randomly divided into group A (control group, n=6), group B (poisoned group, n=30) and group C (smecta-treated group, n=30). Rats in groups B and C were treated intragastrically with PQ at 50 mg/kg, and rats in group A was treated intragastrically with saline (1 mL). Rats in group C were given intragastrically smecta at 400 mg/kg 10 minutes after administration of PQ, while rats in other two groups were treated intragastrically with 1 mL saline at the same time. Live rats in groups B and C were sacrificed at 2, 6, 24, 48, 72 hours after administration of PQ for the determination of paraquat plasma concentrations and for HE staining of the lung, stomach and jejunum. The rats were executed at the end of trial by the same way in group A.

RESULTS:

The plasma concentration of paraquat (ng/mL) ranged from 440.314±49.776 to 4320.6150±413.947. Distinctive pathological changes were seen in the lung, stomach and jejunum in group B. Lung injuries deteriorated gradually, edema, leukocyte infiltration, pneumorrhagia, incrassated septa and lung consolidation were observed. Abruption of mucosa, hyperemic gastric mucosa and leukocyte infiltration were obvious in the stomach. The hemorrhage of jejunum mucosa, the abruption of villus, the gland damage with the addition of inflammatory cell infiltration were found. Compared to group B, the plasma concentration of paraquat reduced (P<0.01) and the pathological changes mentioned above were obviously alleviated in group C (P<0.05, P<0.01).

CONCLUSION:

Smecta reduced the plasma concentration of paraquat and alleviated pathologic injury of rats with PQ poisoning.

Predictors of acute respiratory distress syndrome in patients with paraquat intoxication

Introduction

Paraquat poisoning is characterized by acute lung injury, pulmonary fibrosis, respiratory failure, and multi-organ failure, resulting in a high rate of mortality and morbidity. The objectives of this study were to identify predictors of acute respiratory distress syndrome (ARDS) in cases of paraquat poisoning and determine the association between these parameters.

Materials and Methods

In total, 187 patients were referred for management of intentional paraquat ingestion between 2000 and 2010. Demographic, clinical, and laboratory data were recorded. Sequential organ failure assessment (SOFA) and Acute Kidney Injury Network (AKIN) scores were collected, and predictors of ARDS were analyzed.

Results

The overall mortality rate for the entire population was 54% (101/187). Furthermore, the mortality rate was higher in the ARDS patients than in the non-ARDS patients (80% vs. 43.80%, P<0.001). Additionally, the ARDS patients not only had higher AKIN_48-h scores (P<0.009), SOFA_48-h scores (P<0.001), and time to ARDS/nadir PaO₂ (P=0.008) but also suffered from lower nadir PaO₂ (P<0.001), nadir AaDO₂ (P<0.001), and nadir eGFR (P=0.001) compared to those in the non-ARDS patients. Moreover, pneumomediastinum episodes were more frequent in the ARDS patients than in the non-ARDS patients (P<0.001). A multivariate Cox regression model revealed that blood paraquat concentrations (P<0.001), SOFA_48-h scores (P=0.001), and steroid and cyclophosphamide pulse therapies (P=0.024) were significant predictors of ARDS. The cumulative survival rates differed significantly (P<0.001) between patients with SOFA_48-h scores <3 and SOFA_48-h scores ≥3, with a sensitivity of 95.8%, specificity of 58.4%, and overall correctness of 67.6%. Finally, the area under the receiver operating characteristic (AUROC) analysis showed that SOFA_48-h scores (P<0.001) had a better discriminatory power than blood paraquat concentrations (P=0.01) for predicting ARDS.

Conclusions

The analytical results indicate that SOFA_48-h scores, blood paraquat concentrations, and steroid and cyclophosphamide pulse therapies are significantly associated with ARDS complications after paraquat intoxication.

Sequential Radiologic and Functional Pulmonary Changes in Patients with Paraquat Intoxication

The sequential changes of paraquat-induced pulmonary damage were studied using high-resolution computed tomography (HRCT) and pulmonary function tests (PFTs) in long-term follow-up. Among the cohort of 27 patients who had ingested paraquat, the HRCT findings showed a normal (n = 14) and an abnormal group (n = 13). Increased paraquat ingestion in the abnormal group was associated with more rapid and severe pulmonary changes. Ground-glass opacity on HRCT peaked on day 7 after ingestion. Between 2 weeks and 1 month, consolidation increased and pulmonary fibrosis progressed, and slow improvements were observed for up to six months. Compared with the PFT results obtained at 1 and 6.5 months, FVC, FEV1, and diffusing capacity all improved slightly. Lung changes after paraquat intoxication are functionally and radiologically reversible following treatment.

Spectrum of corrosive esophageal injury after intentional paraquat or glyphosate-surfactant herbicide ingestion

BACKGROUND

Data on the spectrum of corrosive injury to the esophagus after paraquat or glyphosate-surfactant ingestion are sparse in the literature and confined to case studies and brief reports. Therefore, this study aimed to examine the clinical features, degrees of esophageal injury, and clinical outcomes after paraquat or glyphosate herbicide ingestion, and sought to determine what association, if any, may exist between these findings.

METHODS

We performed an observational study on 47 patients with paraquat or glyphosate ingestion who underwent endoscopic evaluation over a period of 11 years (2000-2011).

RESULTS

Corrosive esophageal injuries were classified as grade 1 in 14 (glyphosate-surfactant) and three (paraquat), grade 2a in nine (glyphosate-surfactant) and 18 (paraquat), and grade 2b in one (glyphosate-surfactant) and two (paraquat) patients. No patients had grade 0, 3a, or 3b esophageal injuries. Therefore, the severity of corrosive injury was more severe in the paraquat group (P = 0.005). After toxin ingestion, systemic toxicity occurred, with rapid development of systemic complications in many cases. Neurologic complications occurred more frequently in the glyphosate-surfactant group (29.2% versus 0%, P = 0.005), although respiratory failure (4.2% versus 34.8%, P = 0.008), hepatitis (12.5% versus 52.2%, P = 0.004), and renal failure (20.8% versus 52.2%, P = 0.025) developed more frequently in the paraquat group. Patients with glyphosate poisoning had shorter hospital stays than patients with paraquat poisoning (13.3 ± 15.1 days versus 26.8 ± 10.2 days, P = 0.001). Nevertheless, there was no significant difference in mortality rate between the glyphosate-surfactant and paraquat groups (8.3% versus 13.0%, P = 0.601). We ultimately found that patients with grade 2b esophageal injury suffered from a greater incidence of respiratory (100.0% versus 5.9%, P = 0.001) and gastrointestinal (66.7% versus 11.8%, P = 0.034) complications than patients with grade 1 injury, regardless of herbicide type.

CONCLUSION

Paraquat and glyphosate are mild caustic agents that produce esophageal injuries of grades 1, 2a, and 2b only. Our data also suggest a potential relationship between the degree of esophageal injury and systemic complications.

Paraquat poisoning in pediatric patients

OBJECTIVE

This observational study examined the outcome of Taiwanese pediatric patients with paraquat poisoning and compared these data with the published data on paraquat poisonings from other international poisoning centers.

METHODS

We performed a retrospective study on children with acute paraquat poisoning that were admitted to the Chang Gung Memorial Hospital during a period of 10 years (2000-2010). Of the 193 paraquat poisoning patients, only 6 were children.

RESULTS

The mean age was 8.85 ± 5.55 (1-15.6) years. Younger patients had accidentally swallowed paraquat, whereas older patients had intentionally ingested paraquat. Most patients were referred within a relatively short period (0.5-2.0 hours). Paraquat poisoning was associated with high morbidity and often resulted in severe complications, including acute respiratory distress syndrome and multiple-organ failure. The complications included shock (50.0%), hypoxemia (33.3%), respiratory failure (33.3%), nausea/vomiting (16.7%), abdominal pain (33.3%), hepatitis (66.7%), gastrointestinal tract bleeding (33.3%), acute renal failure (33.3%), and seizures (16.7%). Patients were treated aggressively with a standard detoxification protocol consisting of gastric lavage, active charcoal, charcoal hemoperfusion, and cyclophosphamide and steroid pulse therapies. Secondary bacterial infections were common after hospitalization and included sepsis (33.3%), pneumonia (33.3%), and urinary tract infection (50.0%). In the end, 2 patients (33.3%) died from multiple-organ failure, despite intensive resuscitation.

CONCLUSIONS

Our data (mortality rate, 33.3%) are comparable to the data of other published reports from other international poison centers. Evidently, a prompt diagnosis of paraquat poisoning and an immediate institution of a detoxification protocol is a prerequisite for a favorable outcome.

Sequential organ failure assessment score can predict mortality in patients with paraquat intoxication

Introduction

Paraquat poisoning is characterized by multi-organ failure and pulmonary fibrosis with respiratory failure, resulting in high mortality and morbidity. The objective of this study was to identify predictors of mortality in cases of paraquat poisoning. Furthermore, we sought to determine the association between these parameters.

Methods

A total of 187 patients were referred for management of intentional paraquat ingestion between January 2000 and December 2010. Demographic, clinical, and laboratory data were recorded. Sequential organ failure assessment (SOFA) and acute kidney injury network (AKIN) scores were collected, and predictors of mortality were analyzed.

Results

Overall hospital mortality for the entire population was 54% (101/187). Using a multivariate logistic regression model, it was found that age, time to hospitalization, blood paraquat level, estimated glomerular filtration rate at admission (eGFR _{first day}), and the SOFA_48-h score, but not the AKIN_48-h score, were significant predictors of mortality. For predicting the in-hospital mortality, SOFA_48-h scores displayed a good area under the receiver operating characteristic curve (AUROC) (0.795±0.033, P<0.001). The cumulative survival rate differed significantly between patients with SOFA_48-h scores <3 and those ≥3 (P<0.001). A modified SOFA (mSOFA) score was further developed by using the blood paraquat level, and this new score also demonstrated a better AUROC (0.848±0.029, P<0.001) than the original SOFA score. Finally, the cumulative survival rate also differed significantly between patients with mSOFA scores <4 and ≥4 (P<0.001).

Conclusion

The analytical data demonstrate that SOFA and mSOFA scores, which are based on the extent of organ function or rate of organ failure, help to predict mortality after intentional paraquat poisoning.

Improved survival in severe paraquat poisoning with repeated pulse therapy of cyclophosphamide and steroids

PURPOSE

To clarify the efficacy of repeated methylprednisolone (MP) and cyclophosphamide (CP) pulse therapy and daily dexamethasone (DEX) therapy in patients with severe paraquat (PQ) poisoning.

METHODS

A total of 111 patients with severe PQ poisoning and dark-blue color in urine tests within 24 h of intoxication were included prospectively. The control group consisted of 52 patients who were admitted between 1998 and 2001 and who received high doses of CP (2 mg/kg per day) and DEX (5 mg every 6 h) for 14 days. The study group consisted of 59 patients who were admitted from 2002 to 2007 and who received initial MP (1 g) for 3 days and CP (15 mg/kg per day) for 2 days, followed by DEX (5 mg every 6 h) until a PaO(2) of >80 mmHg had been achieved, or treated with repeated 1 g MP for 3 days and 1 g CP for 1 day if the PaO(2) was <60 mmHg.

RESULTS

There were no differences between the two groups with regard to baseline data and plasma PQ levels. The study group patients had a lower mortality rate (39/59, 66%) than the control group patients (48/52, 92%; P=0.003, log-rank test). Multivariate Cox regression analysis revealed that the repeated pulse therapy was correlated with decreased hazard ratios (HR) for all-cause mortality (HR=0.50, 95% CI 0.31-0.80; P=0.004) and death from lung fibrosis-related hypoxemia (HR=0.10, 95% CI 0.04-0.25; P<0.001) in severely PQ-intoxicated patients.

CONCLUSION

Repeated pulses of CP and MP, rather than high doses of CP and DEX, may result in a lower mortality rate in patients with severe PQ poisoning.

Suicide victim of paraquat poisoning make suitable corneal donor

This report addresses the possibility of expanding transplant corneal donor pool by inclusion of more patients who have suffered poisoning with paraquat pre-mortem. A 27-year-old depressed man committed suicide by ingesting 50 mL of 24% paraquat (Gramoxone, Syngenta, Taiwan). He was treated aggressively with gastric lavage, with large amounts of normal saline, followed by infusion of activated charcoal and magnesium citrate. Blood paraquat level was 1.90 μg/mL. Charcoal hemoperfusion was performed for 8 hours using a charcoal-containing dialysis machine. Furthermore, pulse therapies of cyclophosphamide (15 mg/kg/day for 2 days) and methylprednisolone (1 g/day for 3 days) were administered, followed by dexamethasone (20 mg/day for 14 days). Methylprednisolone pulse therapy was repeated since PaO(2) on the 15th day of poisoning was <60 mm Hg. Chest radiography demonstrated diffuse ground glass opacities of both lungs, with thickening of the intralobular interstitium, compatible with interstitial pneumonitis. Arterial blood gas found persistent hypoxemia and large alveolar-arterial oxygen tension differences. Respiratory failure developed on the 21st day and he was intubated for mechanical ventilatory support. As the patient expressed his wish for organ donation, the corneas were harvested after expiration on the 22nd day. His corneas were transplanted in two recipients and visual acuities of the recipients were doing well at 6 months after transplantation.

Spectrum of corrosive esophageal injury after intentional paraquat ingestion

INTRODUCTION

This is an observational study that examines the clinical features, the degrees of esophageal injury, physiological markers, and clinical outcomes after paraquat ingestion and seeks to determine what association, if any, may exist between these findings.

METHODS

The study included 16 of 1410 paraquat subjects who underwent endoscopies at Chang Gung Memorial Hospital between 1980 and 2007.

RESULTS

Corrosive esophageal injuries were classified as grade 1 in 8, 2a in 5, and 2b in 3 patients. No patients had grade 0, 3a, or 3b esophageal injuries. After paraquat ingestion, systemic toxicity occurred, with rapid development of hypoxia, hepatitis, and renal failure in many cases. Hypoxia occurred in 1 (12.5%), 5 (100%), and 3 (100%) patients with grades 1, 2a, and 2b esophageal injury, respectively. There were more hypoxic patients with grades 2a and 2b than those with grade 1 esophageal injury (P < .05). The nadir Pao(2) was lower in patients with grades 2a and 2b than those with grade 1 esophageal injury (P < .05). However, there were no significant differences in terms of acute hepatitis, peak serum alanine aminotransferase, acute renal failure, and peak serum creatinine between the 3 groups (P > .05). Kaplan-Meier analysis did not find any difference in survival between the groups (P > .05).

CONCLUSION

Paraquat, a mild caustic agent, produces only grades 1, 2a, and 2b esophageal injury. Our findings showed a potential relationship between the degree of hypoxia, mortality, and degree of esophageal injury, although such a low number of study subjects limits the conclusions that can be made by this study.

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.

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.

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.

Repeated pulse of methylprednisolone and cyclophosphamide with continuous dexamethasone therapy for patients with severe paraquat poisoning

OBJECTIVE

Paraquat is widely used in the world, and all treatments for paraquat poisoning have been unsuccessful. Many patients have died of paraquat poisoning in developing countries. A novel anti-inflammation method was developed to treat severe paraquat-poisoned patients with >50% to <90% predictive mortality: initial pulse therapy with methylprednisolone (1 g/day for 3 days) and cyclophosphamide (15 mg/kg/day for 2 days), followed by dexamethasone 20 mg/day until Pao2 was >11.5 kPa (80 mm Hg) and repeated pulse therapy with methylprednisolone (1 g/day for 3 days) and cyclophosphamide (15 mg/kg/day for 1 day), which was repeated if Pao2 was <8.64 kPa (60 mm Hg).

DESIGN

Randomized controlled trial.

SETTING

Academic medical center in Taiwan.

PATIENTS

Twenty-three paraquat-poisoned patients with >50% and <90% predictive mortality assessed by plasma paraquat levels were prospectively and randomly assigned to the control and study groups at a proportion of 1:2.

INTERVENTIONS

The control group received conventional therapy and the study group received the novel repeated pulse treatment with long-term steroid therapy.

MEASUREMENTS AND MAIN RESULTS

We measured patient mortality during the study period. There was not a different distribution of basal variables between the two study groups. The mortality rate (85.7%, six of seven) of the control group was higher than that of the study group (31.3%, five of 16; p = .0272).

CONCLUSIONS

The novel anti-inflammatory therapy reduces the mortality rate for patients with severe paraquat poisoning.

Combined initial cyclophosphamide with repeated methylprednisolone pulse therapy for severe paraquat poisoning from dermal exposure

The article presents a patient with severe paraquat poisoning from dermal exposure, who had chemical bums to more than 10% of his body surface area, serum paraquat level 0.13 microg/mL 60 hr after exposure, and severe hypoxemia (PaO2 41.6 mmHg). The patient was successfully treated with combined initial megadoses of cyclophosphamide (15 mg/kg/day, total 2 days) with repeated methylprednisolone pulse therapy (15 mg/kg/day, total 6 days) and continuous dexamethasone administration (5 mg every 8 hr), and recovered completely without sequelae 3 months later. This treatment deserves further investigation in future clinical trials.

Intravenous paraquat poisoning-induced multiple organ failure and fatality--a report of two cases

Paraquat poisoning is the most common cause of fatal herbicide intoxication, mostly through oral ingestion. This work reports two cases of death following intravenous paraquat injection. The clinical courses of the two cases were fulminated and fatal. Toxic symptoms and severe organ function impairment developed soon after paraquat injection. Timely treatment with activated charcoal hemoperfusion with pulse steroid and cyclophosphamide was attempted in both cases; however, both cases died within five days owing to multiple organ failure. In cases of intravenous paraquat intoxication, toxic signs develop more quicker than with oral ingestion. The prognosis of intravenous paraquat intoxication is extremely poor.

Combined methylprednisolone and dexamethasone therapy for paraquat poisoning

OBJECTIVE

To report a severe case of paraquat poisoning successfully treated with repeated-pulse therapy of methylprednisolone.

DESIGN

Case study.

SETTING

University Hospital, Lin-Kou Medical Center, Taipei, Taiwan, Republic of China.

PATIENTS

A 60-yr-old man with paraquat poisoning with severe acute renal failure (serum creatinine level of 11.8 mg/dL and serum paraquat level of 3.66 microg/mL at 10 hrs after ingestion) and severe hypoxemia (Pao2, 66.6 mm Hg).

INTERVENTION

Repeated 3-day pulse therapy with methylprednisolone, one course of 2-day cyclophosphamide, and a high dose of dexamethasone for 33 days. MEASUREMENTS AND MAIN OUTCOME: Arterial blood gas analysis was obtained regularly. A chest radiography was obtained every week. The arterial blood oxygen concentrations dramatically elevated from 66 mm Hg to 97 mm Hg, and the chest radiographs markedly improved after repeated-pulse therapy with anti-inflammatory agents and cyclophosphamide.

CONCLUSIONS

We successfully treated a severe paraquat poisoned patient with repeated methylprednisolone pulse therapy and prolonged dexamethasone treatment. This case demonstrates that the severe inflammation, not the fibrosis, of the lungs plays a major role in the lethal hypoxemia of patients with paraquat poisoning during the subacute period and confirms our previous hypotheses. Clearly, the use of anti-inflammatory therapy to treat paraquat-poisoned patients needs further evaluation; however, anti-inflammatory therapy may be an effective treatment after failure of standard therapies.