A biological index to predict patient outcome in paraquat poisoning

Isorhynchophylline ameliorates paraquat-induced acute kidney injury by attenuating oxidative stress and mitochondrial damage via regulating toll-interacting expression

Isorhynchophylline (IRN) is an alkaloid with anti-inflammatory and anti-oxidative activities in cardiovascular and brain diseases, but its role in paraquat (PQ)-induced acute kidney injury (AKI) is yet unknown. The model of PQ-induced AKI in rats was established by intraperitoneal injection of PQ (25 mg/kg). We found that the tail vein injection of IRN (4 mg/kg) significantly increased the survival rate of PQ-intoxicated rats. IRN administration alleviated PQ-induced renal injury and renal dysfunction in rats, as evidenced by decreased apoptosis in renal cortex and reduced serum creatinine, serum BUN, and urine NGAL levels. Furthermore, IRN treatment improved the PQ-triggered oxidative stress in renal cortex by increasing the levels of anti-oxidant indicators (SOD activity, GSH/GSSG ratio, levels of Nrf-2, NQO-1, and HO-1 in renal cortex) and decreasing the levels of oxidative stress indexes (ROS and MDA levels in renal cortex). Interestingly, toll-interacting protein (Tollip), a negative regulator of interleukin 1 receptor associated kinase 1 (IRAK1) phosphorylation, was demonstrated to be increased by IRN injection in the renal cortex of PQ-intoxicated rats. In vitro experiments revealed that IRN protected renal tubular epithelial cells against PQ toxicity through suppressing oxidative stress and mitochondrial damage, and these protective effects were reversed by Tollip shRNA. Collectively, the present study demonstrated that IRN ameliorated PQ-induced AKI by attenuating oxidative stress and mitochondrial damage through upregulating Tollip, which provides new insights into the pathogenesis and treatment of PQ poisoning.

Identify the Early Predictor of Mortality in Patients with Acute Paraquat Poisoning

Background

Paraquat is a widely used nonselective and fast-acting contact herbicide worldwide. This study identified the early predictor of mortality in patients with acute paraquat poisoning.

Methods

Twenty-nine patients with acute paraquat poisoning admitted at Nanjing Drum Tower Hospital from January 2018 to August 2020 were included in this study. The early predictor of mortality in patients with acute paraquat poisoning based on the blood tests was identified by correlation, logistic regression, and receiver operating characteristic (ROC) analyses.

Result

15 of the 29 patients died after poisoning. Compared to the survivors, the neutrophilic granulocyte ratio, leukocyte count, ALB, and Crea of the nonsurvivors were significantly higher with p value < 0.05, while the lymphocyte ratio and eGFR(MDRD) of the nonsurvivors were remarkably lower with p value < 0.01. Moreover, the neutrophil-to-lymphocyte ratio (NLR) was remarkably upregulated in the nonsurvivors. The area under the ROC curve (AUC) of the neutrophilic granulocyte ratio, lymphocyte ratio, leukocyte count, ALB, Crea, eGFR(MDRD), and NLR to predict the mortality in patients with acute paraquat poisoning was 0.8905 (95% CI: 0.7589-1.022), 0.8643 (95% CI: 0.7244-1.004), 0.8500 (95% CI: 0.7133-0.9867), 0.7286 (95% CI: 0.5338-0.9233), 0.8167 (95% CI: 0.6620-0.9713), 0.8714 (95% CI: 0.7330-1.010), and 0.8667 (95% CI: 0.7277-1.006), respectively. More interestingly, we also evaluated the diagnostic values of the different combinations of six blood test biomarkers by logistic regression analysis. According to the results of the logistic regression analysis, the AUCs for the combination of the neutrophilic granulocyte ratio, leukocyte count, and eGFR(MDRD) were the largest with 0.986 (95% CI: 0.952-1), and the sensitivity and specificity were 100% and 100%.

Conclusion

This study demonstrated that the combination of the neutrophilic granulocyte ratio, leukocyte count, and eGFR(MDRD) could serve as an ideal early predictor of mortality in patients with acute paraquat poisoning. However, further research is needed to draw a clear conclusion.

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.

Predictive value of the maximum serum creatinine value and growth rate in acute paraquat poisoning patients

This retrospective and a single-center study evaluated the prognostic value of the maximum serum creatinine value (maxCr) and the maximum serum creatinine growth rate (Vmax) after paraquat (PQ) ingestion. One hundred and seventy-one patients with PQ poisoning were treated with a uniform protocol. Demographic variables, clinical manifestations, relevant laboratory data, maxCr and Vmax of all patients were recorded and calculated. The time after PQ ingestion of maxCr and Vmax were also recorded. Vmax and MaxCr exhibited statistically significant differences between the survivor (n = 53) and death (n = 118) groups. Vmax appeared earlier in the death group than the survivor group. Regard to the receiver operating characteristic (ROC) curve analysis, Vmax had an AUC of 0.861 (95% CI, 0.801–0.921) and the optimal cut-off value of 6.21 μmol/(L·h) (sensitivity, 76.3%; specificity, 81.1%). MaxCr had an area under the curve (AUC) of 0.821 (95% CI, 0.752–0.889) and the optimal cut-off value of 225.5 µmol/L (sensitivity, 82.2%; specificity, 67.9%). The comparison of the AUC in the two parameters showed no significant difference, but Vmax appeared earlier than maxCr. Based on binary logistic regression analysis, MaxCr and Vmax both showed strong predictive powers for evaluating the prognosis of acute PQ poisoning patients.

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.

Serum creatinine and cystatin C provide conflicting evidence of acute kidney injury following acute ingestion of potassium permanganate and oxalic acid

AIM

Acute kidney injury (AKI) is common following deliberate self-poisoning with a combination washing powder containing oxalic acid (H₂C₂O₄) and potassium permanganate (KMnO₄). Early and rapid increases in serum creatinine (sCr) follow severe poisoning. We investigated the relationship of these increases with direct nephrotoxicity in an ongoing multicenter prospective cohort study in Sri Lanka exploring AKI following poisoning.

METHODS

Multiple measures of change in kidney function were evaluated in 48 consenting patients who had serial sCr and serum cystatin C (sCysC) data available.

RESULTS

Thirty-eight (38/48, 79%) patients developed AKI (AKIN criteria). Twenty-eight (58%) had AKIN stage 2 or 3. Initial increases in urine creatinine (uCr) excretion were followed by a substantial loss of renal function. The AKIN stage 2 and 3 (AKIN2/3) group had very rapid rises in sCr (a median of 118% at 24 h and by 400% at 72 h post ingestion). We excluded the possibility that the rapid rise resulted from the assay used or muscle damage. In contrast, the average sCysC increase was 65% by 72 h.

CONCLUSIONS

In most AKI, sCysC increases to the same extent but more rapidly than sCr, as sCysC has a shorter half-life. This suggests either a reduction in Cystatin C production or, conversely, that the rapid early rise of sCr results from increased production of creatine and creatinine to meet energy demands following severe oxidative stress mediated by H₂C₂O₄ and KMnO₄. Increased early creatinine excretion supports the latter explanation, since creatinine excretion usually decreases transiently in AKIN2/3 from other causes.

Discernment scheme for paraquat poisoning: A five-year experience in Shiraz, Iran

AIM

To evaluate various schemes for paraquat poisoning and different variables that influence the outcome of acute paraquat poisoning.

METHODS

In a cross-sectional study, the information about all cases of acute paraquat poisoning who were admitted to teaching hospitals affiliated to Shiraz University of Medical Sciences, in a five year period (September 2010 to September 2015) were evaluated. The variables included: Demographic data, medical assessment, therapeutic options, laboratory findings, and the outcomes. Data were analyzed using SPSS, version 22. Significant difference between groups was tested using t-test for continues outcomes and χ² test for categorical. The significance level was considered to be P < 0.05.

RESULTS

A total of 104 patients (66.3% male) were evaluated. The mean age of the female patients was 22.81 ± 9.87 years and the male patients’ was 27.21 ± 11.06 years. Ninety seven (93.3%) of all the cases were suicide attempts with mortality rate of 43.2%. Despite the necessity for emergency hemodialysis during the first 6 h of intoxication, none of the patients had dialysis during this time. Immunosuppressive and corticosteroid medications were not administrated in adequate dosage in 31.1% and 60% of the patients, respectively. Ingestion of more than 22.5 cc of paraquat and increase in creatinine level were the most important predictors of mortality.

CONCLUSION

Treatment should start immediately for these patients. Moreover, creating a clinical guideline according to the findings can have an impact on the treatment procedure which seems to be necessary.

Predicting the probability of survival in acute paraquat poisoning

BACKGROUND

Paraquat (PQ) concentration-time data have been used to predict prognosis for 3 decades. The aim of this study was to find a more accurate method to predict the probability of survival.

METHODS

This study included 788 patients with PQ poisoning who were diagnosed using plasma PQ concentration between January 2005 and August 2012. We divided these patients into 2 groups (survivors vs. nonsurvivors), compared their clinical characteristics, and analyzed the predictors of survival.

RESULTS

The mean age of the included patients was 57 years (range, 14-95 years). When we compared clinical characteristics between survivors (n = 149, 19%) and nonsurvivors (n = 639, 81%), survivors were younger (47 ± 14 years vs. 59 ± 16 years) and had lower plasma PQ concentrations (1.44 ± 8.77 μg/mL vs. 80.33 ± 123.15 μg/mL) than nonsurvivors. On admission, serum creatinine was lower in survivors than in nonsurvivors (0.95 ± 0.91 mg/dL vs. 1.88 ± 1.27 mg/dL). In multivariate logistic regression analysis, age and logarithmically converted serum creatinine [ln(Cr)], [ln(time)], and [ln(PQ)] were assessed as prognostic factors to predict survival in PQ poisoning. The predicted probability of survival using significant prognostic factors was exp (logit)/[1 + exp(logit)], where logit = -1.347 + [0.212 × sex (male = 1, female = 0)] + (0.032 × age) + [1.551 × ln(Cr)] + [0.391 × ln(hours since ingestion)] + [1.076 × ln(plasma PQ μg/mL)]. With this equation, the sensitivity and specificity were 86.5% and 98.7%, respectively.

CONCLUSION

Age, ln(Cr), ln(time), and ln(PQ) were important prognostic factors in PQ poisoning, and our equation can be helpful to predict the survival in acute PQ poisoning patients.

Mechanisms underlying early rapid increases in creatinine in paraquat poisoning

Background

Acute kidney injury (AKI) is common after severe paraquat poisoning and usually heralds a fatal outcome. The rapid large increases in serum creatinine (Cr) exceed that which can be explained by creatinine kinetics based on loss of glomerular filtration rate (GFR).

Methods and Findings

This prospective multi-centre study compared the kinetics of two surrogate markers of GFR, serum creatinine and serum cystatin C (CysC), following paraquat poisoning to understand and assess renal functional loss after paraquat poisoning. Sixty-six acute paraquat poisoning patients admitted to medical units of five hospitals were included. Relative changes in creatinine and CysC were monitored in serial blood and urine samples, and influences of non-renal factors were also studied.

Results

Forty-eight of 66 patients developed AKI (AKIN criteria), with 37 (56%) developing moderate to severe AKI (AKIN stage 2 or 3). The 37 patients showed rapid increases in creatinine of >100% within 24 hours, >200% within 48 hours and >300% by 72 hours and 17 of the 37 died. CysC concentration increased by 50% at 24 hours in the same 37 patients and then remained constant. The creatinine/CysC ratio increased 8 fold over 72 hours. There was a modest fall in urinary creatinine and serum/urine creatinine ratios and a moderate increase in urinary paraquat during first three days.

Conclusion

Loss of renal function contributes modestly to the large increases in creatinine following paraquat poisoning. The rapid rise in serum creatinine most probably represents increased production of creatine and creatinine to meet the energy demand following severe oxidative stress. Minor contributions include increased cyclisation of creatine to creatinine because of acidosis and competitive or non-competitive inhibition of creatinine secretion. Creatinine is not a good marker of renal functional loss after paraquat poisoning and renal injury should be evaluated using more specific biomarkers of renal injury.

APACHE score, Severity Index of Paraquat Poisoning, and serum lactic acid concentration in the prognosis of paraquat poisoning of Chinese Patients

Many prognostic indictors have been studied to evaluate the prognosis of paraquat poisoning. However, the optimal indicator remains unclear. To determine the value of the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, the Severity Index of Paraquat Poisoning (SIPP), and serum lactate levels in the prognosis of paraquat poisoning, we performed a prospective study that enrolled 143 paraquat patients. Data were collected from patients (161) at West China Hospital in Chengdu, China, including details about the patients' general conditions, laboratory examinations, and treatment. Receiver operating characteristic curves for predicting inpatient mortality based on APACHE II score, SIPP, and lactate levels were generated. To analyze the best cutoff values for lactate levels, APACHE II scores, and SIPP in predicting the prognosis of paraquat poisoning, the initial parameters on admission and 7-day survival curves of patients with lactate levels greater than or equal to 2.95 mmol/L, APACHE II score greater than or equal to 15.22, and SIPP greater than or equal to 5.50 h · mg/L at the time of arrival at West China Hospital were compared using the 1-way analysis of variance and the log-rank test. The APACHE II score (5.45 [3.67] vs 11.29 [4.31]), SIPP (2.78 [1.89] vs 7.63 [2.46] h · mg/L), and lactate level (2.78 [1.89] vs 7.63 [2.46] mmol/L) were significantly lower in survivors (77) after oral ingestion of paraquat, compared with nonsurvivors (66). The APACHE II score, SIPP, and lactate level had different areas under the curve (0.847, 0.789, and 0.916, respectively) and accuracy (0.64, 0.84, and 0.89, respectively). Respiratory rate, serum creatinine level, Paco2, and mortality rate at 7 days after admission in patients with lactate levels greater than or equal to 2.95 mmol/L were markedly different compared with those of other patients (P < 0.05). The predictive value of lactic acid was superior to that of APACHE II score and SIPP for acute oral paraquat poisoning.

The time between paraquat ingestion and a negative dithionite urine test in an independent risk factor for death and organ failure in acute paraquat intoxication

To identify a prognostic marker that is less sensitive to variations in the elapsed time since paraquat ingestion, we assessed the time between paraquat ingestion and a negative dithionite urine test as a prognostic parameter in patients with acute paraquat intoxication. Forty-one patients with acute paraquat intoxication were enrolled in this study and analyzed to verify significant determinants of mortality and organ dysfunction. The amount of paraquat ingested, paraquat plasma levels, and the time to a negative urine dithionite test were significant independent risk factors predicting mortality. The amount of paraquat ingestion, and the time to a negative urine dithionite test were independent risk factors predicting organ dysfunction. With a cut-off value of 34.5 hr for the time to negative conversion of the urine dithionite test, the sensitivity and specificity for mortality were 71.4% and 75.0%, respectively. The incidence of acute kidney injury and respiratory failure above 34.5 hr were 100% and 85.0%, respectively. In conclusion, the time to a negative urine dithionite test is the reliable marker for predicting mortality and/or essential organ failure in patients with acute paraquat intoxication, who survive 72 hr.

Changes in the concentrations of creatinine, cystatin C and NGAL in patients with acute paraquat self-poisoning

An increase in creatinine >3 μmol/L/h has been suggested to predict death in patients with paraquat self-poisoning and the value of other plasma biomarkers of acute kidney injury has not been assessed. The aim of this study was to validate the predictive value of serial creatinine concentrations and to study the utility of cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) as predictors of outcome in patients with acute paraquat poisoning. The rate of change of creatinine (dCr/dt) and cystatin C (dCyC/dt) concentrations were compared between survivors and deaths. Receiver-operating characteristic (ROC) curves were constructed to determine the best threshold for predicting death. Paraquat was detected in 20 patients and 7 of these died between 18 h and 20 days post-ingestion. The dCr/dt ROC curve had an area of 0.93 and the cut-off was >4.3 μmol/L/h (sensitivity 100%, specificity 85%, likelihood ratio 7). The dCyC/dt ROC curve had an area of 0.97 and the cutoff was >0.009 mg/L/h (sensitivity 100%, specificity 91%, likelihood ratio 11). NGAL did not separate survivors from deaths. Death due to acute paraquat poisoning is associated with changes in creatinine and cystatin concentrations. Further validation of these measurements is needed before they can be adopted in guiding intensive treatments.

Rapid analysis of plasma paraquat using sodium dithionite as a predictor of outcome in acute paraquat poisoning

BACKGROUND

Paraquat poisoning can be lethal, and aggressive treatments might have little or no effect on severely poisoned patients. Accordingly, a convenient prognostic test is necessary to guide therapy for acute paraquat poisoning. Sodium dithionite reduces paraquat to a blue radical form in alkaline plasma with a paraquat detection sensitivity of 2.0 mg/L, which is a 100% lethal concentration at 10 to 12 hours postingestion. The prognostic utility of this simple reaction was examined prospectively.

METHODS

Of 233 paraquat-poisoned patients, who were taken to the hospital within 12 hours after ingestion, the plasma samples obtained on arrival were tested using the sodium dithionite reaction. Standard saline containing 2.0 mg/L paraquat was used as the positive control. The test result was interpreted as being positive when the plasma test yielded a blue color darker than that of the positive control. The effects of aggressive treatment, including cyclophosphamide pulse and continuous venovenous hemofiltration, were evaluated retrospectively.

RESULTS

The discharge survival rate was 41.6% (97 of 233). Ninety-seven of 142 patients with negative or equivocal plasma dithionite test survived. However, all 91 patients with positive plasma dithionite test died of multiorgan failure. Cyclophosphamide and/or continuous venovenous hemofiltration could not improve survival.

CONCLUSIONS

In this single-center study, a positive plasma dithionite test was associated with 100% mortality, despite aggressive treatment. In contrast, negative or equivocal tests were associated with a 68% survival rate. It is believed that after further verification, this test can be used to guide therapy and predict the outcomes of patients suffering acute paraquat poisoning.

The clinical features of acute kidney injury in patients with acute paraquat intoxication

BACKGROUND

Paraquat (PQ) is a non-selective herbicide that generates reactive oxygen species in vivo. We hypothesized that acute kidney injury (AKI) in patients with acute PQ poisoning would provide a model for the clinical features of ROS-induced AKI.

METHODS

From January 2007 to December 2007, 278 patients with acute PQ intoxication were included in the study. AKI was defined based on the RIFLE classification. The serial changes of creatinine (Cr), the incidence of AKI and the mortality according to the RIFLE classification were analysed.

RESULTS

An initial serum Cr >1.2 mg/dL was a significant predictor of mortality [odds ratio 9.00, 95% C.I. (4.747, 17.061), P < 0.01]. The incidence of AKI was 51.4% among the 173 patients who had an initial serum Cr < or =1.2 mg/dL. Among them, 34.7% were the failure group and oliguric AKI was observed in 10 patients. The average peak serum Cr level, among the 13 survivors in the failure group, was 4.38 mg/dL at the fifth day, after ingestion, and their Cr level normalized within 3 weeks. None of the 13 survivors had permanent loss of renal function. The estimated amount of PQ ingestion was a predictor of the incidence of AKI. The mortality risk was significantly higher in the failure group than in the group without failure.

CONCLUSION

The clinical feature was characterized by fully developed AKI at the fifth day after PQ ingestion and normalized within 3 weeks without exception.

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.

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.

Associations between laboratory parameters and outcome of paraquat poisoning

Paraquat, a non-selective herbicide, is a known fatal substance in humans, and intentional ingestion of paraquat is increasing among Korean suicides. In 1999, 147 subjects admitted to the Institute of Pesticide Poisoning, Soonchunhyang Chunan Hospital, Korea ingested paraquat. Initial routine laboratory tests were conducted and the outcome of paraquat poisoning was categorized as survivor and fatality. Mean amount (S.D.) of ingestion was 54.5 (104.9) ml, and the overall fatality rate was 44.2%. Abnormal liver function (GOT and GPT), renal dysfunction (BUN and creatinine), metabolic acidosis (pH and PaCO(2)), and abnormal urine analysis (RBC, WBC, and protein) had significant odds ratios (ORs) for paraquat fatality (P<0.05). In multiple logistic regression, subjects with liver or renal dysfunction or metabolic acidosis had significant risks of the fatality. Our results determined that initial routine laboratory parameters could be used to predict the outcome of paraquat poisoning and recommended that evaluation of acid-base status and renal and liver function should be conducted and evaluated before intensive therapy.

[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.

Acute paraquat poisoning: increased toxicity in one case with high alcohol intake

Human paraquat poisoning from accidental or intentional ingestion is very often fatal. According to the amount of paraquat involved, death can occur within hours or weeks following ingestion. The inefficacy of the various treatments undertaken have led to determine prognostic factors based upon the evolution of plasma and urine paraquat concentrations or of usual biochemical parameters. We report one case of acute poisoning which, although the ingested dose of paraquat was not massive (< 50 mg/kg-1) and the severity indices were in favour of a delayed fatal outcome, has ended in an early death. The high blood alcohol level of the patient (3.34 g l-1) seems to be the main cause of the precocity of this death (86th hour).