Pulse therapy with cyclophosphamide and methylprednisolone in patients with moderate to severe paraquat poisoning: a preliminary report

Acute paraquat poisoning in an adolescent with compromised outcome: A case report

Paraquat, a highly toxic herbicide, accounts for a substantial number of poisoning-related fatalities, primarily prevalent in agricultural regions. The ingestion gives rise to severe complications affecting various organs, including the lungs, gastrointestinal tract, kidneys and liver. This report details the case of an 18-year-old male who had been using cannabis for a year and inadvertently ingested paraquat. He presented at the emergency room exhibiting symptoms of vomiting characterized by hematemesis and regurgitated food particles, along with heartburn, dysphagia and reduced urine output. Given the absence of a specific antidote, the prognosis for paraquat poisoning remains generally unfavourable. Diagnosis relies on circumstantial evidence and clinical manifestations, necessitating a focus on supportive care. Presently, no specific antidote for paraquat poisoning is available. Efforts should concentrate on preventive measures, efficient decontamination strategies and vigilant stabilization protocols in instances of exposure.

Paraquat induced acute kidney and lung injury with a dramatic response to methylprednisolone: A case report

Background

Paraquat poisoning is one of the leading causes of fatal poisoning in many parts of the world, especially in agricultural countries. Its high toxicity even in small amounts causes rapid damage to multiple organs, especially the kidneys, lungs, and liver, mainly through free radical-mediated injury. As no specific antidote is yet available, early diagnosis and the importance of supportive therapy are critical parts of management. Some evidence suggests a survival benefit from using immunosuppressive drugs.

Case report

This case presentation concerns a 15-year-old boy from a village with a history of herbicide poisoning, later confirmed to be paraquat. Despite supportive therapy her condition continued to deteriorate with features of kidney and lung damage. The patient was then treated with methylprednisolone 500 mg daily for 5 days, along with other supportive care, and has made a remarkable recovery.

Conclusions

High efficacy as an herbicide, availability and low cost make paraquat an easy-to-encounter poison for suicidal or accidental use. Its high fatality calls for urgent and effective strategies to save lives. Methylprednisolone may play a role in its treatment.

Single-Center Experience with Mass Paraquat Exposure in Nine Patients

Paraquat dichloride is a widely used, highly toxic chemical herbicide and a significant cause of fatal poisonings. Toxicity is thought to be secondary to generation of reactive oxygen species. Hours after exposure, patients may experience signs and symptoms ranging from nausea to multi-system organ failure. To mitigate complications and death, immunosuppression with cyclophosphamide and corticosteroid-based therapies have shown to be an effective option in limited studies. Our objective is to report our center's experience treating patients that had been exposed to paraquat over a two-day period. Patients were identified using our Institutional Burn Center registry, and linked to the clinical and administrative data. Demographics, length of stay, costs and mortality were evaluated. There were nine patients admitted from the exposure. All were male. All survived. Eight were undocumented migrant farmers. The average age was 36 years (25-59 years). The average length of stay was 3.3 days (2-5 days). Seventy-eight percent had cutaneous injury, but only one required debridement and placement of a skin substitute. Thirty-three percent complained of continued shortness of breath after discharge. Average total hospital cost was $28,131 ($9,500-$51,000). Paraquat is a highly toxic herbicide and exposure can be fatal if not treated promptly. Immediate decontamination and repeated pulse therapy with cyclophosphamide and methylprednisolone may be life-saving.

A Case of Paraquat Poisoning Presenting With Spontaneous Pneumothorax and Pneumomediastinum

Paraquat (1,1’-dimethyl-4,4’-dipyridylium) is a liquid herbicide associated with accidental and suicidal ingestion, leading to fatal toxicity. It can lead to multiple organ dysfunction, including metabolic acidosis, acute kidney and liver injury, pulmonary fibrosis, and acute respiratory distress syndrome (ARDS). Very rarely, this can present with spontaneous pneumothorax or pneumomediastinum or both, which are poor prognostic markers with a mortality rate of almost 100%. Here, we present a young male presenting with paraquat poisoning followed by the development of both pneumothorax and pneumomediastinum and death from respiratory failure. Paraquat poisoning should always be considered in the differential diagnosis in patients presenting with spontaneous pneumothorax or pneumomediastinum in places with high paraquat poisoning prevalence.

Immunosuppressive drugs to reduce the mortality rate in patients with moderate to severe paraquat poisoning: A Meta-analysis

The benefits and adverse effects of immunosuppressive drugs (ISDs) in patients with paraquat (PQ) poisoning have not been thoroughly assessed. This meta-analysis study aims to evaluate the effect of ISDs in patients with moderate to severe PQ poisoning. We searched PubMed, Embase, Cochrane Library, Ovid Medline, CNKI and Wanfang Data from inception to January 2019. The Mantel-Haenszel method with a random-effects model was used to calculate the pooled relative risks (RRs) and 95% Confidence Intervals (CIs) as described by DerSimonian and Laird. An L'Abbé plot was drawn to explore the relationship between the degree of poisoning and mortality. Four randomized controlled trials, two prospective and seven retrospective studies were identified. ISDs were significantly associated with reduced mortality (RR 0.76; 95% CI, 0.58-0.99) and the incidence rate of multiple-organ dysfunction syndrome (MODS) (RR 0.63; 95% CI, 0.48-0.83) in patients with moderate to severe PQ poisoning. They were not associated with an increased incidence rate of hepatitis and reduced incidence rate of acute renal failure and hypoxia. The L'Abbé plot results showed a slight increase in mortality rate in the ISD group with increased mortality in the placebo group. This indicates a possible advantage of ISDs in most of the patients with severe PQ poisoning. These findings suggest that ISDs may reduce the mortality and incidence rate of MODS in moderate to severe PQ poisoning patients, and severe PQ poisoning patients might benefit more from ISDs.

Systematic review and meta-analysis of the efficacy and safety of immunosuppressive pulse therapy in the treatment of paraquat poisoning

Paraquat (PQ), a highly effective herbicide, is widely used worldwide. PQ poisoning can cause multiple organ failure, in which the lung is the primary target organ. After PQ poisoning, the patient mortality rate is as high as 90%, and there is currently no specific antidote. The main clinical treatment is the use of glucocorticoids and cyclophosphamide for pulse therapy, but its effectiveness and safety are still uncertain. We investigated the effectiveness and safety of immunosuppressive pulse therapy with glucocorticoids and cyclophosphamide to evaluate the treatment value in patients with acute PQ poisoning. This meta-analysis, combined with seven trials that enrolled a total of 426 patients, showed that immunosuppressive pulse therapy with glucocorticoids and cyclophosphamide for PQ poisoning significantly reduced mortality of the study group (59.3%, 134/226) compared with the control group (81.0%, 162/200). There was no significant difference of hepatitis or renal failure between the control and study groups, indicating that immunosuppressive pulse therapy was relatively safe. Several patients were reported to have leukopenia and returned to normal after 1-2 weeks without any abnormalities. Two cases of non-fatal sepsis were reported and considered to be a side effect of the immunosuppressive pulse therapy. Thus, immunosuppressive pulse therapy can efficiently reduce the mortality of PQ poisoning and it is relatively safe.

Is endotracheal intubation a non-beneficial treatment in patients with respiratory failure due to paraquat poisoning?

Introduction

Paraquat poisoning can result in dysfunction of multiple organs, and pulmonary fibrosis with respiratory failure is the major cause of mortality. For terminally ill patients, some life-prolonging treatments can be non-beneficial treatments (NBT). The objective of this study was to determine if intubation is a NBT for patients with respiratory failure due to paraquat poisoning.

Methods

The study included 68 patients with respiratory failure due to paraquat poisoning. Patients were hospitalized at MacKay Memorial Hospital, Taitung Branch, Taiwan, between 2005 to April 2016. Composite outcomes of intra-hospital mortality, the rate of do-not-resuscitate (DNR) orders, prescribed medications, length of stay, and medical costs were recorded and compared between the do-not-intubate (DNI) group and endotracheal intubation (EI) group.

Results

Intra-hospital mortality rate for the entire population was 100%. There were significantly more patients with DNR orders in the DNI group (P = 0.007). There were no differences in the length of hospital stay. However, patients in DNI group had significantly less vasopressor use and more morphine use, shorter time in the intensive care unit, and fewer medical costs.

Conclusion

The procedure of intubation in patients with respiratory failure due to paraquat poisoning can be considered inappropriate life-prolonging treatment.

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.

Treatment Outcome of Combined Continuous Venovenous Hemofiltration and Hemoperfusion in Acute Paraquat Poisoning: A Prospective Controlled Trial

OBJECTIVES

To investigate whether combined continuous venovenous hemofiltration and hemoperfusion among paraquat-poisoned patients would improve survival.

DESIGN

Prospective, controlled interventional study over 4 years.

SETTING

Single, tertiary, academic medical center.

PATIENTS

We recruited patients admitted to Shanghai Tenth People's Hospital within 48 hours after paraquat ingestion. Exclusions were under 14 years old, ingestion of paraquat with other toxicants, pregnant, a history of chronic pulmonary disease, psychosis, hyperthyroidism, or diabetes with impaired liver or renal function.

INTERVENTIONS

All patients were assigned to receive continuous venovenous hemofiltration with hemoperfusion therapy (continuous venovenous hemofiltration group) and to receive conventional therapy (conventional group). The study outcomes were death from any cause within 90 days after paraquat ingestion and the frequencies of hypoxia, acute kidney injury, or adverse events.

MEASUREMENTS AND MAIN RESULTS

Of the 110 enrolled patients, 59 were assigned to continuous venovenous hemofiltration group and 51 to conventional group. The two groups had similar baseline demographics and clinical features. At 90 days after paraquat ingestion, 19 of 59 patients (32.2%) in the continuous venovenous hemofiltration group and 29 of 51 patients (56.9%) in the conventional group had died (hazard ratio, 0.43; 95% CI, 0.24-0.76; p = 0.004). In multivariable Cox proportional hazard models controlling for baseline characteristics, combined continuous venovenous hemofiltration and hemoperfusion was independently associated with reduced risk of death compared with conventional therapy (adjusted hazard ratio, 0.35; 95% CI, 0.19-0.64; p = 0.001). Patients in the continuous venovenous hemofiltration group, as compared to the conventional group, had a reduced occurrence rate of hypoxia (40.7% vs 72.5%; p = 0.001) and of acute kidney injury (59.3% vs 78.4%; p = 0.03). Hypophosphatemia and thrombocytopenia were more common in the continuous venovenous hemofiltration group (p < 0.05).

CONCLUSIONS

In patients with paraquat poisoning, treatment with combined continuous venovenous hemofiltration and hemoperfusion significantly improved 90-day survival rates.

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.

Case Series of Paraquat Poisoning in Tuen Mun Hospital

Paraquat is highly toxic to human and is widely used in agriculture as a contact herbicide. However, it is easily accessible in agricultural product shops. Seven cases of paraquat poisoning were treated in Tuen Mun Hospital from 1998–2005. The mortality (4 out of 7) was very high. One patient died after oral exposure to paraquat despite immunosuppressive and antioxidant therapies. The mechanism of toxicity and potential new therapies of paraquat poisoning are discussed in the article.

Prolonged methylprednisolone therapy after the pulse treatment for patients with moderate-to-severe paraquat poisoning: A retrospective analysis

This retrospective study aims to evaluate the effect of prolonged methylprednisolone (MP) therapy on the mortality of patients with moderate-to-severe paraquat (PQ) poisoning after the pulse treatment.We performed a retrospective analysis of patients with acute moderate-to-severe PQ poisoning that were admitted to the emergency department from May 2012 to August 2016. Out of 138 patients, 60 were treated with pulse treatment (15 mg kg day MP for 3 days) and 78 were treated with prolonged MP therapy after pulse treatment (15 mg kg day MP for 3 days; afterward, the dosage was reduced in half every 2 days, and the MP therapy was terminated until 0.47 mg kg day). Kaplan-Meier method was used to compare the mortality between the 2 groups. Cox proportional hazard models were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI).The mortality of the prolonged MP therapy after pulse treatment group was lower than that of the pulse group (47.4% vs 63.3%; log-rank tests, P  =  .003). According to the multivariate Cox analysis, the prolonged MP therapy after pulse treatment was significantly associated with a lower mortality risk (HR: 0.31, 95% CI: 0.19-0.52, P < .001) compared with the pulse group. In addition, the prolonged MP therapy after pulse treatment caused more incidences of leucopenia than the pulse treatment alone (25.6% vs 11.7%, P  =  .04).The prolonged MP therapy after pulse treatment can reduce the mortality of moderate-to-severe PQ poisoning patients.

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.

Effects of prolonged methylprednisolone treatment after pulse therapy for paraquat-intoxicated rats

OBJECTIVE

This study was designed to evaluate prolonged methylprednisolone (MP) treatment after pulse therapy for paraquat (PQ)-intoxicated rats.

METHOD

Acute PQ toxicity was induced by intraperitoneally injecting single toxic dose of 25 mg/kg of body weight. Rats were divided into four groups: control group (saline solution for 15 days), PQ group (saline solution for 15 days after PQ toxicity), pulse group (15 mg·kg^-1·day^-1 MP for 3 days after PQ toxicity and then saline solution for 12 days) and pulse + prolonged group (15 mg·kg^-1·day^-1 MP for 3 days after PQ toxicity; dosage was subsequently reduced by half every 2 days, and MP was terminated until 0.47 mg·kg^-1·day^-1). Hydroxyproline (HYP) content in lung tissues was evaluated through enzyme-linked immunosorbent assay, and lung fibrosis was examined using a semiquantitative scoring system (Ashcroft staging criteria). Lung wet-to-dry weight (W/Dc) ratio and 15-day survival rates of the rats were also analysed.

RESULTS

Similar survival rates (55.0 vs. 65.0%) were obtained for the pulse group and the pulse + prolonged group. The W/Dc (4.79 ± 0.42 vs. 5.29 ± 0.35), HYP content in the lung tissues (3.23 ± 0.24 vs. 3.72 ± 0.23 μg/mg) and lung fibrosis scores (2.69 ± 0.74 vs. 3.12 ± 0.60) of the pulse + prolonged group were lower than those of the pulse group.

CONCLUSION

Prolonged MP treatment after pulse therapy could effectively ameliorate PQ-intoxicated acute lung injury in rats. However, further studies should be performed to verify our findings.

Prediction of paraquat exposure and toxicity in clinically ill poisoned patients: a model based approach

AIMS

Paraquat poisoning is a medical problem in many parts of Asia and the Pacific. The mortality rate is extremely high as there is no effective treatment. We analyzed data collected during an ongoing cohort study on self-poisoning and from a randomized controlled trial assessing the efficacy of immunosuppressive therapy in hospitalized paraquat-intoxicated patients. The aim of this analysis was to characterize the toxicokinetics and toxicodynamics of paraquat in this population.

METHODS

A non-linear mixed effects approach was used to perform a toxicokinetic/toxicodynamic population analysis in a cohort of 78 patients.

RESULTS

The paraquat plasma concentrations were best fitted by a two compartment toxicokinetic structural model with first order absorption and first order elimination. Changes in renal function were used for the assessment of paraquat toxicodynamics. The estimates of toxicokinetic parameters for the apparent clearance, the apparent volume of distribution and elimination half-life were 1.17 l h(-1) , 2.4 l kg(-1) and 87 h, respectively. Renal function, namely creatinine clearance, was the most significant covariate to explain between patient variability in paraquat clearance.This model suggested that a reduction in paraquat clearance occurred within 24 to 48 h after poison ingestion, and afterwards the clearance was constant over time. The model estimated that a paraquat concentration of 429 μg l(-1) caused 50% of maximum renal toxicity. The immunosuppressive therapy tested during this study was associated with only 8% improvement of renal function.

CONCLUSION

The developed models may be useful as prognostic tools to predict patient outcome based on patient characteristics on admission and to assess drug effectiveness during antidote drug development.

Efficacy and safety of pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide in patients with paraquat poisoning: A meta-analysis

PURPOSE

Paraquat (PQ) is widely used in developing countries. Accidental or suicidal PQ poisoning is a public health concern due to lack of effective treatment. Because the role of pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide for PQ poisoning is uncertain, we performed a meta-analysis to investigate the efficacy and safety of the therapy.

METHOD

A systematic literature search for randomized controlled trials (RCTs) and other clinical studies was performed in Pub Med, Embase, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature and Retrieval System, and Chinese Medical Current Contents. We estimated pooled relative risk ratios (RRs) and 95% confidence intervals (CIs) using a fixed effect model or random effect model. Outcomes included mortality, incidence of acute renal failure (ARF) and hypoxia, and leucopenia.

RESULTS

Five studies (three RCTs) involving 332 PQ poisoning patients met the criteria. The mortality of moderate to fulminant poisoning patients receiving the pulse therapy was lower than that of the controls (60.4% vs. 85.3%; RR 0.71, 95% CI: 0.59, 0.86, P=0.0004). The therapy also reduced the mortality of patients with moderate to severe PQ poisoning (45.1% vs. 79.1%, RR 0.45; 95% CI: 0.28, 0.75, P=0.002). However, the therapy did not decrease the incidence of ARF and hypoxia. In addition, the pulse therapy caused more leucopenia than the controls (36.9% vs. 2.6%; RR: 9.12; 95% CI: 3.65, 22.81, P<0.00001).

CONCLUSION

Pulse immunosuppressive therapy with glucocorticoid and cyclophosphamide may reduce the mortality of PQ poisoning patients, although the therapy may cause leucopenia.

Psychiatric comorbidity and its impact on mortality in patients who attempted suicide by paraquat poisoning during 2000-2010

BACKGROUND

Paraquat poisoning is a lethal method of suicide used around the world. Although restricting its accessibility had been widely discussed, the underlying psychopathological mechanism of paraquat self-poisoning and its association with mortality have not yet been explicitly evaluated.

METHODS

We included all patients admitted to a tertiary general hospital in Taiwan between 2000 and 2010 following a suicide attempt by paraquat self-administration. Diagnoses were made upon psychiatric consultation based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. The risk of mortality was calculated by logistic regression with various psychiatric or medical covariates.

RESULTS

The consultation-liaison psychiatry team assessed 157 patients who attempted suicide by paraquat poisoning. Mood disorders (54.0%), including dysthymic (26.7%) and major depressive disorders (24.7%), were the most common psychiatric diagnoses among the self-poisoning patients. Among those who attempted suicide, 87 patients (58.0%) died and dysthymic disorder (OR = 5.58, 95% CI: 1.13-27.69; p < 0.05) significantly increased the mortality risk after adjustment for relevant medical variables, including age, gender, severity index of paraquat poisoning (SIPP), and risk for respiratory failure.

CONCLUSIONS

Awareness of comorbid psychiatric illnesses, especially dysthymic disorder, is vital in the prevention and treatment of suicide by paraquat poisoning.

Diagnostic and therapeutic approach for acute paraquat intoxication

Paraquat (PQ) has known negative human health effects, but continues to be commonly used worldwide as a herbicide. Our clinical data shows that the main prognostic factor is the time required to achieve a negative urine dithionite test. Patient survival is a 100% when the area affected by ground glass opacity is <20% of the total lung volume on high-resolution computed tomography imaging 7 days post-PQ ingestion. The incidence of acute kidney injury is approximately 50%. The average serum creatinine level reaches its peak around 5 days post-ingestion, and usually normalizes within 3 weeks. We obtain two connecting lines from the highest PQ level for the survivors and the lowest PQ level among the non-survivors at a given time. Patients with a PQ level between these two lines are considered treatable. The following treatment modalities are recommended to preserve kidney function: 1) extracorporeal elimination, 2) intravenous antioxidant administration, 3) diuresis with a fluid, and 4) cytotoxic drugs. In conclusion, this review provides a general overview on the diagnostic procedure and treatment modality of acute PQ intoxication, while focusing on our clinical experience.

Survival predictors in paraquat intoxification and role of immunosuppression

Paraquat poisoning resulted in multiorgan failure and is associated with high mortality. We audited 83 historical cases of paraquat poisoning in past 2 years treated with conventional decontamination and supportive treatment, followed by enrolling 85 patients over a 2 year period into additional immunosuppression with intravenous (i.v.) methylprednisolone and i.v. cyclophosphamide.

Our results showed that age, poor renal function and leucocytosis are the main predictors of fatal outcome. Immunosuppression regime rendered higher survival (6 out of 17 patients (35.3%)) versus historical control (1 out of 18 patients (5.6%)) (p = 0.041) in the cohort with admission eGFR < 50 ml/min/1.73 m² and WBC count > 11,000/μL.

In contrast, there was no difference in survival with immunosuppression regime (38 out of 64 patients (59.4%)) compared to historical control (30 out of 52 patients (57.7%)) (p = 0.885) in those with eGFR > 50 ml/min/1.73 m² or WBC < 11,000/μL at presentation.

Multivariable logistic regression showed survival probability = exp(logit)/(1 + exp(logit)), in which logit = 13.962 − (0.233 × ln(age (year))) − (1.344 × ln(creatinine (μmol/L))) − (1.602 × ln(rise in creatinine (μmol/day))) – (0.614 × ln(WBC (,000/μL))) + (2.021 × immunosuppression) and immunosuppression = 1 if given and 0 if not. Immunosuppression therapy yielded odds ratio of 0.132 (95% confidential interval: 0.029–0.603, p = 0.009).

In conclusion, immunosuppression therapy with intravenous methylprednisolone and cyclophosphamide may counteract immune mediated inflammation after paraquat poisoning and improve survival of patients with admission eGFR < 50 ml/min/1.73 m² and WBC count > 11,000/μL.

Addition of immunosuppressive treatment to hemoperfusion is associated with improved survival after paraquat poisoning: a nationwide study

Paraquat poisoning associates very high mortality rate. Early treatment with hemoperfusion is strongly suggested by animal and human studies. Although the survival benefit of additional immunosuppressive treatment (IST) in combination with hemoperfusion is also reported since 1971, the large-scale randomized control trials to confirm the effects of IST is difficult to be executed. Therefore, we designed this nationwide large-scale population-based retrospective cohort study to investigate the outcome of paraquat poisoning with hemoperfusion and the additional effects of IST combined with hemoperfusion. This nationwide retrospective cohort study utilized data retrieved from the National Health Insurance Research Database (NHIRD) of Taiwan. A total of 1811 hospitalized patients with a diagnosis of paraquat poisoning who received hemoperfusion between 1997 and 2009 were enrolled. The mean age of all 1811 study subjects was 47.3 years. 70% was male. The overall survival rate was only 26.4%. Respiratory failure and renal failure were diagnosed in 56.2% and 36% patients. The average frequency of hemoperfusion was twice. IST was added in 42.2% patients. IST significantly increases survival rate (from 24.3% to 29.3%, P<0.001). The combined IST with methylprednisolone, cyclophosphamide and dexamethasone associates with the highest survival rate (48%, P<0.001). Moreover, patients younger than 45 years of age in the IST group had the best survival (41.0% vs. 33.7%, p<0.001). Our results support the use of IST with hemoperfusion for paraquat-poisoned patients. The best survival effect of IST is the combination of methylprednisolone, cyclophosphamide and daily dexamethasone, especially in patients with younger age.

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.

Amelioration of Paraquat-Induced Pulmonary Injury by Mesenchymal Stem Cells

Acute paraquat (PQ) poisoning induces redox cycle and leads to fatal injury of lung. Clinical management is supportive in nature due to lack of effective antidote, and the mortality is very high. Mesenchymal stem cells (MSCs) process the properties of immunomodulation, anti-inflammatory, and antifibrotic effects and oxidative stress resistance. MSC transplantation may theoretically serve as an antidote in PQ intoxication. In this study, we examined the potential therapeutic effects of MSCs in PQ-induced lung injury. The degree of PQ toxicity in the rat type II pneumocyte cell line, L2, and MSCs was evaluated by examining cell viability, ultrastructural changes, and gene expression. L2 cells treated with 0.5 mM PQ were cocultured in the absence or presence of MSCs. For the in vivo study, adult male SD rats were administered an intraperitoneal injection of PQ (24 mg/kg body weight) and were divided into three groups: group I, control; group II, cyclophosphamide and methylprednisolone; group III, MSC transplantation 6 h after PQ exposure. MSCs were relatively resistant to PQ toxicity. Coculture with MSCs significantly inhibited PQ accumulation in L2 cells and upregulated the expression of antioxidative heme oxygenase 1 and metallothionein 1a genes, reversed epithelial-to-mesenchymal transition, and increased the viability of PQ-exposed L2 cells. Treatment with MSCs resulted in a significant reduction in severity of liver and renal function deterioration, alleviated lung injury, and prolonged the life span of rats. Altogether, our results suggest that MSCs possess antidote-like effect through multifactorial protection mechanism. The results of this preclinical study demonstrate that transplantation of MSCs may be a promising therapy and should be further validated clinically.

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.

Spectrum of toxic hepatitis following intentional paraquat ingestion: analysis of 187 cases

INTRODUCTION

This retrospective observational study examined the clinical features, the degrees of toxic hepatitis, physiological markers and clinical outcomes after intentional paraquat poisoning and sought to determine what association, if any, might exist between these findings.

METHODS

A total of 187 patients were referred for management of intentional paraquat ingestion between 2000 and 2010. Patients were categorized into two groups according to their hepatic complication, i.e. with (N = 87) or without (N = 100) toxic hepatitis. Demographic, clinical and laboratory data were obtained for analysis. Mortality rates were also analysed.

RESULTS

It was found that patients with toxic hepatitis were younger (39.7 ± 13.7 vs 44.2 ± 16.6 year old, P = 0.046), and suffered from greater incidences of acute respiratory failure (63.2 vs 48.0%, P = 0.037) and acute renal failure (75.9 vs 56.0%, P = 0.004) than patients without hepatitis. The hospitalization period was longer in patients with hepatitis than without hepatitis (16.2 ± 14.6 vs 11.2 ± 12.1 days, P = 0.012), even though there was no difference in mortality rate between both groups (56.3 vs 53.0%, P = 0.649). Notably, the symptoms of toxic hepatitis developed within 6.7 ± 6.3 days of exposure to paraquat with aspartate aminotransferase (AST) 138 ± 156 U/L, alanine aminotransferase (ALT) 127 ± 114 U/L and total bilirubin 2.7 ± 2.6 mg/dL. The hepatitis peaked at 9.5 ± 8.8 days with AST 125 ± 139 U/L, ALT 183 ± 181 U/L and total bilirubin 3.2 ± 3.6 mg/dL. Nevertheless, the symptoms resolved within 17.3 ± 9.8 days of paraquat exposure, and none of the patients died of hepatic complication.

CONCLUSIONS

A substantial proportion of paraquat patients suffered from hepatic complication (46.52%), but the spectrum of hepatitis in these patients seemed mild and transient.

Successful treatment of patients with paraquat intoxication: three case reports and review of the literature

OBJECTIVE

To report on three patients with paraquat (PQ) intoxication surviving after combined therapy with hemoperfusion (HP), cyclophosphamide (CTX), and glucocorticoid.

METHODS

Three patients suffered acute renal failure in a few days after ingesting a lethal amount of PQ. Chest computed tomography (CT) scans revealed obvious pulmonary inflammation, pleural effusion, and fibrous lesions several days after ingestion. HP was performed immediately, followed by large doses of glucocorticoid (methylprednisolone, 500 g/d) and CTX (approximately 4 g).

RESULTS

After 50 d of treatments, all three patients were discharged in healthy condition, with chest CT showing small fibrous lesions, exudation, and both lungs clear of auscultation.

CONCLUSIONS

The protective effect of the lungs may have been due to timely treatment at adequate doses.

Medical management of paraquat ingestion

Poisoning by paraquat herbicide is a major medical problem in parts of Asia while sporadic cases occur elsewhere. The very high case fatality of paraquat is due to inherent toxicity and lack of effective treatments. We conducted a systematic search for human studies that report toxicokinetics, mechanisms, clinical features, prognosis and treatment. Paraquat is rapidly but incompletely absorbed and then largely eliminated unchanged in urine within 12-24 h. Clinical features are largely due to intracellular effects. Paraquat generates reactive oxygen species which cause cellular damage via lipid peroxidation, activation of NF-κB, mitochondrial damage and apoptosis in many organs. Kinetics of distribution into these target tissues can be described by a two-compartment model. Paraquat is actively taken up against a concentration gradient into lung tissue leading to pneumonitis and lung fibrosis. Paraquat also causes renal and liver injury. Plasma paraquat concentrations, urine and plasma dithionite tests and clinical features provide a good guide to prognosis. Activated charcoal and Fuller's earth are routinely given to minimize further absorption. Gastric lavage should not be performed. Elimination methods such as haemodialysis and haemoperfusion are unlikely to change the clinical course. Immunosuppression with dexamethasone, cyclophosphamide and methylprednisolone is widely practised, but evidence for efficacy is very weak. Antioxidants such as acetylcysteine and salicylate might be beneficial through free radical scavenging, anti-inflammatory and NF-κB inhibitory actions. However, there are no published human trials. The case fatality is very high in all centres despite large variations in treatment.

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.

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.

[Immunosuppressive treatment due to paraquat poisoning]

Paraquat is the most important member of the bipyridyl compound. It is directly caustic in nature and it exerts its herbicidal activity by inhibiting the reduction of NADP to NADPH during photosynthesis, a process in which superoxide, singlet oxygen, hydroxyl, and peroxide radicals are formed. Human tissue toxicity likely results from a similar oxidative mechanism. After oxidative destruction, recruitment of inflammatory cells leads to late onset and irreversible pulmonary fibrosis. Ingestion greater than 20-40 mg/kg of paraquat concentrate should be aggressively managed with the administration of intestinal decontaminants and hemoperfusion. Low-inspired oxygen therapy should be given until it becomes impractical in the face of hypoxemia. Administration of immunodepressive therapy, steroids and cyclophosphamide, should be considered. In addition, there should be intermittent assessment of pulmonary function and of plasma and urinary concentrations of paraquat.

Acute paraquat poisoning: report of a survival case following intake of a potential lethal dose

When properly used, paraquat (PQ) is a widely used bipyridil herbicide with a good safety record. Most cases of PQ poisoning result from intentional ingestion, with death resulting from hypoxemia secondary to lung fibrosis in moderate to severe poisonings. With high ingestion volumes (>50 mL of a 20% wt/vol formulation), death results from multiple organ failure and cardiovascular collapse within 1 week after intoxication. The present report describes a successful clinical case regarding the intoxication of a 15-year-old girl by a presumed lethal dose of PQ. The adolescent ingested approximately 50 mL of a commercialized concentrate (20% wt/vol of dichloride salt) formulation of PQ. High serum and urinary levels of PQ confirmed the bad prognosis. However, the therapeutic protocol followed in the present clinical case led to a positive outcome. Besides the measures for decreasing PQ absorption and increasing its elimination, other protective procedures were applied in aiming to reduce the production of reactive oxygen species (ROS), to scavenge ROS, to repair ROS-induced lesions, and to reduce inflammation. The status-of-the-art concerning the biochemical and toxicological aspects of PQ poisoning and the pharmacologic basis of the respective treatment is also presented.

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.

Subacute pulmonary manifestation in a survivor of severe paraquat intoxication

Paraquat has been widely used as a nonselective contact herbicide since 1962. It is highly toxic for humans, and many cases of acute poisoning, especially intentional self-poisoning, have been reported over the past few decades in developing countries. Ingestion of a threshold volume results in multiple organ failure and death after a longer period of time, but aggressive clinical studies are rarely done when the diagnosis is clear. We report the case of a patient who survived severe paraquat intoxication; he presented with subacute pulmonary manifestations including physiologic dysfunction and abnormalities on radiographs.

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.

Prospects for treatment of paraquat-induced lung fibrosis with immunosuppressive drugs and the need for better prediction of outcome: a systematic review

BACKGROUND

Acute paraquat self-poisoning is a significant problem in parts of Asia, the Pacific and the Caribbean. Ingestion of large amounts of paraquat results in rapid death, but smaller doses often cause a delayed lung fibrosis that is usually fatal. Anti-neutrophil ('immunosuppressive') treatment has been recommended to prevent lung fibrosis, but there is no consensus on efficacy.

AIM

To review the evidence for the use of immunosuppression in paraquat poisoning, and to identify validated prognostic systems that would allow the use of data from historical control studies and the future identification of patients who might benefit from immunosuppression.

DESIGN

Systematic review.

METHODS

We searched PubMed, Embase and Cochrane databases for 'paraquat' together with 'poisoning' or 'overdose'. We cross-checked references and contacted experts, and searched on [www.google.com] and [www.yahoo.com] using 'paraquat', 'cyclophosphamide', 'methylprednisolone' and 'prognosis'.

RESULTS

We found ten clinical studies of immunosuppression in paraquat poisoning. One was a randomized controlled trial (RCT). Seven used historical controls only; the other two were small (n = 1 and n = 4). Mortality in controls and patients varied markedly between studies. Three of the seven non-RCT controlled studies measured plasma paraquat; analysis using Proudfoot's or Hart's nomograms did not suggest that immunosuppression increased survival in these studies. Of 16 prognostic systems for paraquat poisoning, none has been independently validated in a large cohort.

DISCUSSION

The authors of the RCT have performed valuable and difficult research, but their results are hypothesis-forming rather than conclusive; elsewhere, the use of historical controls is problematic. In the absence of a validated prognostic marker, a large RCT of immunosuppression using death as the primary outcome is required. This RCT should also prospectively test and validate the available prognostic methods, so that future patients can be selected for this and other therapies on admission.

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.

Adult respiratory distress syndrome in the tropics

Today ARDS is more frequently recognized and managed in tropical countries, although published data from most locations is meager. The spectrum of disorders causing ARDS in tropical countries includes virtually all conditions encountered in the West. Additionally, tropical infections and other disorders are seen far more commonly. In particular, malaria and TB are important infections that predispose patients to ARDS in the tropics. Both of these illnesses give lead to severe forms of disease, such as falciparum malaria, acute miliary TB or TB bronchopneumonia, and may cause ARDS. Awareness of the complications helps in early recognition and differential diagnosis from several similar manifestations. Although earlier reports painted a gloomy picture of the outcome of these patients in general--mainly due to financial and logistic constraints--the scenario is improving quickly with better and wider availability of newer diagnostic and management tools.

[Paraquat poisoning. A study of 29 cases and evaluation of the effectiveness of the "Caribbean scheme"]

BACKGROUND

To study clinical aspects of the oral paraquat intoxication and to assess the effectiveness of both the charcoal haemoperfusion and the so-called "Caribbean scheme" (cyclophosphamide, dexamethasone, furosemide and vitamins B and C) to reduce its mortality.

PATIENTS AND METHOD

Retrospective study of 29 consecutive cases admitted to our intensive care unit in 17 years.

RESULTS

a) Twenty five men and four women ingested 20% paraquat solution, either accidentally (4 subjects) or deliberately (25 subjects). The suicidal purpose was particularly strong among men aged 50-66 years. Most of patients had vomits and diarrhoea. All patients developed oral and pharyngeal caustic lesions. Hypokalaemia was detected on admission in 9 patients. Increased levels of serum aminotransferases, bilirubin, amylase or creatinkinase were detected in some patients. Twenty two patients developed acute renal failure and 18 patients respiratory failure. Twenty patients died (ten in the first 48 hours and ten between days 3 and 30); b) charcoal haemoperfusion was performed on 16 patients; 4 of the 16 treated patients survived, versus 5 of the 13 non treated (p = NS), and c) the "Caribbean scheme" was applied on 18 patients. All but one of the 11 subjects who ingested >= 45 ml (treated with the "Caribbean scheme" or not) died. Among those who ingested 45 ml, 8 of the 12 treated patients survived, versus none of the 6 non treated ones (p < 0.05).

CONCLUSIONS

Charcoal haemoperfusion did not reduce mortality of paraquat. The "Caribbean scheme" was associated with a lesser mortality in the subjects who ingested 45 ml of 20% paraquat solution.

[Massive paraquat poisoning. Favorable course after treatment with n-acetylcysteine and early hemodialysis]

Case report of a 30-year-old patient, admitted one hour after an intentional ingestion of paraquat (60 g). The initial treatment included gastric washing, parenteral n-acetylcysteine and forced diuresis. Considering the severity of the intoxication, conventional haemodialysis was started four hours after the ingestion. Plasma concentrations of paraquat, in the lethal range at admission, decreased rapidly and significantly after haemodialysis. This case raises the question of the part played by n-acetylcysteine and haemodialysis respectively in a favourable outcome. As the determination of paraquat blood concentrations requires some delay, these data are of no help for therapeutic decisions. Therefore, in cases of massive poisoning or uncertainty of the ingested dose, a technique of blood purification in indicated. Charcoal haemoperfusion is the most efficient, however conventional haemodialysis, which is more widespread, should be considered if the former is not available.