Clinical Implications of the Ethane in Exhaled Breath in Patients With Acute Paraquat Intoxication

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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 MDR1 gene polymorphisms on mortality in paraquat intoxicated patients

Paraquat is a fatal herbicide following acute exposure. Previous studies have suggested that multidrug resistance protein 1 (MDR1) might help remove paraquat from the lungs and the kidney. MDR1 single-nucleotide polymorphisms (SNPs) are involved in the pharmacokinetics of many drugs. The purpose of this study was to determine whether MDR1 SNPs were associated with the mortality in paraquat intoxicated patients. We recruited 109 patients admitted with acute paraquat poisoning. They were genotyped for C1236T, G2677T/A, and C3435T single-nucleotide polymorphisms (SNPs) of MDR1 gene. Their effects on mortality of paraquat intoxicated patients were evaluated. Overall mortality rate was 66.1%. Regarding the C1236T of the MDR1 gene polymorphism, 21 (19.3%) had the wild type MDR1 while 88 (80.7%) had homozygous mutation. Regarding the C3435T MDR1 gene polymorphism, 37(33.9%) patients had the wild type, 23 (21.1%) had heterozygous mutation, and 49 (45.0%) had homozygous mutation. Regarding the G2677T/A MDR1 gene polymorphism, 38 (34.9%) patients had the wild type, 57 (52.3%) had heterozygous mutation, and 14 (12.8%) had homozygous mutation. None of the individual mutations or combination of mutations (two or three) of MDR1 SNP genotypes altered the morality rate. The mortality rate was not significantly different among SNP groups of patients with <4.0 μg/mL paraquat. In conclusion, MDR1 SNPs have no effect on the mortality rate of paraquat intoxicated patients.

Pneumomediastinum predicts early mortality in acute paraquat poisoning

CONTEXT

In paraquat (PQ) poisoning, death often occurs after the appearance of pneumomediastinum (PM). However, the clinical features and eventual outcome of PM in PQ intoxication remains unclear.

OBJECTIVE

We aimed to characterize PM following PQ poisoning and its prognostic value for predicting mortality.

MATERIALS AND METHODS

Enrolled PQ-poisoned patients (n = 75) were divided into two groups according to whether PM could be detected by chest computed tomography or not. The study outcomes included 5- and 90-day death after intoxication. Survival curves were derived using the Kaplan-Meier method, and mortality risk factors were analyzed by forward stepwise Cox regression analysis.

RESULTS

PM was documented in 21.3% of the patients (16/75); in 13 of them PM set in within 3 days of PQ ingestion. 15 patients died within 3 days of appearance of PM. Compared with patients without PM, those with PM were younger (P = 0.011), and had higher scores of Acute Physiology and Chronic Health Evaluation (P < 0.001) and Sequential Organ Failure Assessment (P = 0.003). In addition, patients with PM had a higher incidence of acute renal failure (P = 0.001), toxic hepatitis (P = 0.008), and respiratory insufficiency (P = 0.003). PM predicted an increased risk of 90-day death (93.8% of patients with PM vs. 40.7% among those without PM; hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.0-5.6; P = 0.045), and increased risk of 5-day death (81.3% vs. 27.1%; HR, 3.2; 95% CI, 1.2-8.1; P = 0.017).

DISCUSSION AND CONCLUSION

Early PM, occurring within 8 days, is a specific predictor of mortality in PQ poisoning.

The volume ratio of ground glass opacity in early lung CT predicts mortality in acute paraquat poisoning

BACKGROUND

Pulmonary injury is the main cause of death in acute paraquat (PQ) poisoning. However, whether quantitative lung computed tomography (CT) can be useful in predicting the outcome of PQ poisoning remains unknown. We aimed to identify early findings of quantitative lung CT as predictors of outcome in acute PQ poisoning.

METHODS

Lung CT scanning (64-slide) and quantitative CT lesions were prospectively measured for patients after PQ intoxication within 5 days. The study outcome was mortality during 90 days follow-up. Survival curves were derived by the Kaplan-Meier method, and mortality risk factors were analyzed by the forward stepwise Cox regression analysis.

RESULTS

Of 97 patients, 41 (42.3%) died. Among the eight different types of lung CT findings which appeared in the first 5-day of PQ intoxication, four ones discriminated between survivors and non-survivors including ground glass opacity (GGO), consolidation, pneumomediastinum and "no obvious lesion". With a cutoff value of 10.8%, sensitivity of 85.4% and specificity of 89.3%, GGO volume ratio is better than adopted outcome indicators in predicting mortality, such as estimated amount of PQ ingestion, plasma or urine PQ concentration, acute physiology and chronic health evaluation (APACHE) II and sequential organ failure assessment (SOFA) scores. GGO volume ratios above 10.8% were associated with increased mortality (hazard ratio, 5.82; 95% confidence interval, 4.77-7.09; P < 0.001).

CONCLUSIONS

The volume ratio of GGO exceeding 10.8% is a novel, reliable and independent predictors of outcome in acute PQ poisoning.

Prediction of patient survival in cases of acute paraquat poisoning

Paraquat concentration-time data have been used to predict the clinical outcome following ingestion. However, these studies have included only small populations, although paraquat poisoning has a very high mortality rate. The purpose of this study was to develop a simple and reliable model to predict survival according to the time interval post-ingestion in patients with acute paraquat poisoning. Data were retrospectively collected for patients who were admitted with paraquat poisoning to Soonchunhyang University Choenan Hospital between January 2005 and December 2012. Plasma paraquat levels were measured using high-performance liquid chromatography. To validate the model we developed, we used external data from 788 subjects admitted to the Presbyterian Medical Center, Jeonju, Korea, between January 2007 and December 2012. Two thousand one hundred thirty six patients were included in this study. The overall survival rate was 44% (939/2136). The probability of survival for any specified time and concentration could be predicted as (exp(logit))/(1+exp(logit)), where logit = 1.3544+[−3.4688×log10(plasma paraquat μg/M)]+[−2.3169×log10(hours since ingestion)]. The external validation study showed that our model was highly accurate for the prediction of survival (C statics 0.964; 95% CI [0.952–0.975]). We have developed a model that is effective for predicting survival after paraquat intoxication.

Comparison between kidney and continuous plasma perfusion for paraquat elimination

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of exhaled nitric oxide in acute paraquat poisoning: a pilot study

BACKGROUND

Fractional exhaled nitric oxide (FENO) is nitric oxide (NO) in the lower airway measured by oral exhalation. FENO can be a useful non-invasive marker for asthma. Paraquat-mediated lung injury can be reflective of an ROS-induced lung injury. We aimed to verify if FENO is a clinical parameter of ROS formation and responsiveness to medical therapies in acute paraquat intoxication.

MATERIAL AND METHODS

We recruited 12 patients admitted with acute paraquat poisoning. A portable and noninvasive device called NIOX MINO™ (Aerocrine AB, Solna, Sweden) was used to measure FENO. Measurements were made at the time of hospital admission and at 24, 48, 72, 96, and 120 h after paraquat ingestion.

RESULTS

Six out of the total 12 recruited patients had general conditions (e.g. oral pain) that made it difficult for them to exhale with adequate force. Mean plasma paraquat level was 1.4 ± 2.5 g/mL. We found no direct correlation between the paraquat levels (both ingestion amount and plasma concentration) and FENO (initial, maximal, and minimal values). All the measured FENO values were no greater than 20 ppb for the 2 patients who died. FENO did not vary more than 20% from the baseline. Compared to the above findings, FENO measurements were found to be greater than 20 ppb for the patients who survived. FENO tends to reach its peak value at between 50 h and 80 h.

CONCLUSIONS

FENO did not predict mortality, and there was no increase of FENO in patients with severe paraquat intoxication.

The area of ground glass opacities of the lungs as a predictive factor in acute paraquat intoxication

Even though plasma paraquat (PQ) levels have known to be an informative predictor, many patients succumb at low PQ levels in acute PQ intoxication. This study was designed to see whether the high resolution computerized tomography (HRCT) of the lungs would be a predictive measure in acute PQ intoxication. HRCT of the lungs was obtained from 119 patients with acute PQ intoxication on 7 days after PQ ingestion. The areas with ground glass opacities (GGOs) were evaluated at five levels with the area measurement tool of the picture archiving and communication systems. Among 119 patients, 102 survived and 17 died. The plasma PQ levels were significantly higher in the non-survivors than in the survivors (2.6+/-4.0 microg/mL vs. 0.2+/-0.4 microg/mL, P=0.02). The area with GGOs was 2.0+/-6.4% in the survivors and 73.0+/- 29.9% in the non-survivors (P<0.001). No patients survived when the area with GGOs was more than 40% but all of the patients survived when the area affected by GGOs was less than 20%. In conclusion, the area of GGOs is a useful predictor of survival in acute PQ intoxication, especially in patients with low plasma PQ levels.

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.