The amount of paraquat ingested dictates the extent of organs damage and symptoms [1]. Ingestion of more than 50 to 100 ml of 20% (w/v) liquid concentrate is very likely to cause multi-system organ failure (pulmonary, cardiac, renal, and liver) and death within a few hours to days following ingestion [2].

Immediate symptoms include pain and swelling of the mouth, throat, and upper airway. Ingestion of a small quantity of paraquat causes pulmonary and renal toxicity over a period of 2 to 6 days. Pulmonary toxicity is characterized by acute alveolitis and pulmonary edema over a period of 1 to 3 days, followed by an aggressive development of pulmonary fibrosis. Manifestations of acute renal failure (e.g., decreased urinary output, severely elevated creatine, cystatin C, and BUN levels) and/or liver toxicity (jaundice and elevated transaminases levels) are also common [3] [4].

Some degree of gastrointestinal (GI) toxicity is almost always present in those with paraquat ingestion. GI symptoms may include mucosal lesions of the mouth and tongue (‘paraquat tongue’), pharynx, esophagus, and stomach within the first several days of ingestion. Abdominal pain, nausea, vomiting, and/or diarrhea may also be present. Patients that present with mediastinitis and/or pneumomediastinum secondary to esophageal perforation have a high mortality rate [5].

• Fever

  A 57-year-old farmer developed breathlessness, high fever and interstitial infiltrates in the upper and middle lung fields few days after percutaneous paraquat poisoning with rapid evolution to pulmonary fibrosis. [ncbi.nlm.nih.gov]

  […] bipyridilium herbicide that has been banned in Europe), usually occurring through ingestion of the poison, and that presents with caustic injury of the oral cavity and pharynx, as well as nausea, vomiting, epigastric pain, lethargy, loss of consciousness and fever [orpha.net]

  He was referred to our hospital after 5 days He had fever for 1 day with complaints of breathlessness, hematemesis, dark stools, reduced urine output, and epigastric pain. [mjdrdypu.org]

  He was relatively well for several months after the surgery, when he developed fever and cough and was admitted to the hospital with impression of infected bulla and lung abscess. [ircmj.com]

• Rigor

  The proposed method was rigorously evaluated against the real-life dataset in terms of accuracy, sensitivity, and specificity. Additionally, the feature selection was investigated to identify correlating factors for the risk status. [ncbi.nlm.nih.gov]

• Intravenous Drugs

  Herein, we present a case of an intravenous drug abuser who injected paraquat in an effort to commit suicide. He received hemoperfusion and intravenous cyclophosphamide treatment and parenteral pulse therapy with methylprednisolone. [ncbi.nlm.nih.gov]

• Vomiting

  CONCLUSION: A large amount of ingested PQ, vomiting and age may be important variables to consider in association with the high fatality rate of PQ poisoning. [ncbi.nlm.nih.gov]

   Kidney disease and age 50yrs- bad prognosis  Time of ingestion  Painful mouth, difficulty in swallowing, nausea, vomiting, abdominal pain  Burning skin sensation  Respiratory complaints-systemic poisoning 6. [slideshare.net]

• Nausea

  She presented with discomfort, nausea and vomiting. She had drunk a small wine glass full of paraquat. After 18 days in the hospital, the girl developed neutropenia. This is the first reported case of paraquat poisoning-induced neutropenia. [ncbi.nlm.nih.gov]

  […] poisoning is a rare intoxication with paraquat (a non-selective bipyridilium herbicide that has been banned in Europe), usually occurring through ingestion of the poison, and that presents with caustic injury of the oral cavity and pharynx, as well as nausea [orpha.net]

  Abdominal pain, nausea, vomiting, and/or diarrhea may also be present. Patients that present with mediastinitis and/or pneumomediastinum secondary to esophageal perforation have a high mortality rate. [symptoma.com]

  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%). [journals.lww.com]

• Abdominal Pain

  He later developed abdominal pain, subcutaneous emphysema and difficulty in breathing. Following transfer to a district hospital and then to a teaching hospital, poisoning with paraquat was suspected only on day 11 of the illness. [ncbi.nlm.nih.gov]

  He developed hematemesis, epigastric burning, and abdominal pain. The details of the treatment were not available. [mjdrdypu.org]

• Diarrhea

  Lab evaluation  General testing:  Blood tests- on admission, every 6 to 12th hourly for first 48 hours, then based on clinical severity- vomiting, diarrhea, kidney injury.  If prognosis is poor - palliative measures 8.  Serum electrolytes- may be [slideshare.net]

  Abdominal pain, nausea, vomiting, and/or diarrhea may also be present. Patients that present with mediastinitis and/or pneumomediastinum secondary to esophageal perforation have a high mortality rate. [symptoma.com]

  Asymptomatic, vomiting, diarrhea, minimal hepatic, and renal lesions; decrease in pulmonary diffusion capacity, chances of complete recovery. Moderate-to-severe acute poisoning 20-30, 40-50. [mjdrdypu.org]

  When ingested, paraquat poisoning results in severe gastrointestinal distress, including vomiting, diarrhea, abdominal pain, ulcers in the mouth and esophagus, etc. [petpoisonhelpline.com]

  Soon after, they may experience: nausea abdominal pain vomiting diarrhea that may be bloody The gastrointestinal symptoms are often severe. They can lead to both dehydration and low blood pressure. [healthline.com]

• Jaundice

  Case 2 (alive) showed mild liver dysfunction without jaundice. [ncbi.nlm.nih.gov]

  decreased urinary output, severely elevated creatine, cystatin C, and BUN levels) and/or liver toxicity (jaundice and elevated transaminases levels) are also common. [symptoma.com]

  Physical examination revealed mild jaundice and swelling and redness of the throat. Laryngoscopy showed redness and necroses of the hypopharynx, the epiglottis and the vocal cords. [bmcpharmacoltoxicol.biomedcentral.com]

  Figure 1 Photograph of the patient of the described case, the oral mucosa is observed with edema, jaundice and ulcerations. [medcraveonline.com]

• Tachycardia

  Immediate vomiting, diarrhea, abdominal pain, mouth and throat ulceration; within day renal, hepatic failure, hypotension, and tachycardia. Within 1 week hemoptysis, pleural effusion, pulmonary fibrosis. Most commonly leads to death in 2-3 weeks. [mjdrdypu.org]

  Diagnosing toxicity from vital signs Bradycardia (PACED) Propranolol (beta-blockers), poppies (opiates), propoxyphene, physostigmine Anticholinesterase drugs, antiarrhythmics Clonidine, calcium channel blockers Ethanol or other alcohols Digoxin, digitalis Tachycardia [segwfg.nl]

• Retrosternal Chest Pain

  A 15-year-old boy presented with a 1-month history of retrosternal chest pain with no obvious cause. High-resolution computed tomography showed pneumomediastinum. [ncbi.nlm.nih.gov]

• Myopathy

  The patient subsequently developed a progressive, severe, toxic myopathy with generalized weakness and inability to maintain spontaneous ventilation. [ncbi.nlm.nih.gov]

• Burning Skin Sensation

   Kidney disease and age 50yrs- bad prognosis  Time of ingestion  Painful mouth, difficulty in swallowing, nausea, vomiting, abdominal pain  Burning skin sensation  Respiratory complaints-systemic poisoning 6. [slideshare.net]

• Denial

  After all likely causes of pneumomediastinum were eliminated, the diagnosis of occult paraquat poisoning was made when serum paraquat concentration was revealed at 467.40 ng/mL, despite the patient's denial of ingestion or contact. [ncbi.nlm.nih.gov]

• Dysthymic Disorder

  CONCLUSIONS: Awareness of comorbid psychiatric illnesses, especially dysthymic disorder, is vital in the prevention and treatment of suicide by paraquat poisoning. [ncbi.nlm.nih.gov]

• Oliguria

  Clinical features of paraquat toxicity Mild overdose: Nausea and vomiting Diarrhoea Intestinal hemorrhage Haemoptysis Oliguria Minimal renal dysfunction Moderate overdose: Renal failure (ATN within 12-24hours) Pulmonary oedema Hepatotoxicity Pulmonary [derangedphysiology.com]

  Renal system Paraquat is eliminated mainly by the urinary tract, renal failure being oliguria and anuric acid main complication. [medcraveonline.com]

• Anuria

  Increase in serum Cr to 200% to 300% ( 2 to 3-fold) from baseline 0.5 mL/kg/h for more than 12 h Stage 3 Increase in serum Cr to 300% (3-fold) from baseline (or serum Cr of 4.0 mg/dL with an acute increase of at least 0.5 mg/dL 0.3 mL/kg/h for 24 h or anuria [journals.plos.org]

Clinicians should first obtain a thorough history that includes the patient's comorbidities, the strength and quantity of paraquat ingested, and the time of ingestion [6] [7]. The physical exam includes an inspection of the patient's skin and eyes for signs of topical contact, the mouth and pharynx for irritation or ulcerations, auscultation of the chest for crackles which may indicate alveolitis, and the palpation of the abdomen.

The patient's vital signs should be continuously monitored, including respiratory rate and oxygen saturation levels given the high likelihood of pulmonary injury. An arterial blood gas test may be used to evaluate resultant lung injury. A low PaCO2 with concurrent tachypnea indicates the progression of hypoxia. PaO2 steadily declines as paraquat-induced lung injury proceeds; a PaO2 less than 60 mmHg has been associated with a significant rise in mortality [8].

Laboratory tests

Quantitative serum and urine paraquat levels should be obtained to ascertain the degree of intoxication [9]. The concentration of paraquat in the body relative to the time of paraquat ingestion predicts the likelihood of death [10]. The dithionite urine test becomes positive for paraquat about six hours following a large ingestion [11]. The serum level usually peaks one hour after ingestion, followed by a rapid decline as it is redistributed to other compartments in the body.

Imaging tests

A chest radiography may be performed in patients with symptoms indicative of acute lung injury, hypoxia, hyperventilation, and/or crackles on admission, but it has weak sensitivity. A high-resolution computed tomography of the chest could be performed to ascertain the extent of lung injury, about one week after ingestion [12] [13] [14].

• Gliosis

  Examination of the brain by electron microscopy showed oedema and destruction of myelin with abundant myelin breakdown products, and astrocytic fibrous gliosis. [ncbi.nlm.nih.gov]

• Liver Biopsy

  We have examined liver biopsy specimens from two cases of paraquat poisoning. Case 1 (fatal) presented severe intrahepatic jaundice, and liver biopsy showed centrilobular cholestasis with extensive bile duct loss. [ncbi.nlm.nih.gov]

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