Paraquat toxicity: Difference between revisions
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==Background==
==Background==
Paraquat is an herbicide that has a rapid and large distribution and can be fatal even with small ingestions. It has a high case-fatality rate (>50%)<ref>Gawaramanna I, Buckley N. Medical management of paraquat ingestion. Br J Clin Pharmacol. 2011;72(5):745–757</ref> which makes it a frequent means of suicide in the developing world, as well as a dangerous accidental occupational exposure.
*Paraquat is an herbicide that has a rapid and large distribution and can be fatal even with small ingestions. It has a high case-fatality rate (>50%)<ref>Gawaramanna I, Buckley N. Medical management of paraquat ingestion. Br J Clin Pharmacol. 2011;72(5):745–757</ref> which makes it a frequent means of suicide in the developing world, as well as a dangerous accidental occupational exposure.
 
*Paraquat exerts its toxic effects via multiple proposed mechanisms, including lipid peroxidation and generation of reactive oxygen species, direct mitochondrial toxicity, and apoptosis.
Paraquat exerts its toxic effects via multiple proposed mechanisms, including lipid peroxidation and generation of reactive oxygen species, direct mitochondrial toxicity, and apoptosis.


==Clinical Features==
==Clinical Features==
[[File:Paraquat tongue.jpg|thumb|Paraquat Tongue (Credit: wikitox.org)]]
[[File:Paraquat tongue.jpg|thumb|Paraquat Tongue (Credit: wikitox.org)]]


Overall, pulmonary and renal toxicities predominate and are the primary cause of mortality. GI toxicity is nearly universal and is probably an underrecognized cause of mortality secondary to erosion and perforation.  
Overall, pulmonary and renal toxicities predominate and are the primary cause of mortality. GI toxicity is nearly universal and is probably an under-recognized cause of mortality secondary to erosion and perforation.  


*Gastrointestinal: predominate early  
*Gastrointestinal: predominate early  
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*[https://wikem.org/wiki/Ingested_foreign_body Foreign Body Ingestion]
*[https://wikem.org/wiki/Ingested_foreign_body Foreign Body Ingestion]


=Oral Burns/Mucositis=
===Oral [[Burns]]/Mucositis===
*[https://wikem.org/wiki/Burns Burns]
*[https://wikem.org/wiki/Burns Burns]
*Infectious Causes
*Infectious Causes
**Aphthous Ulcer
**[[Aphthous stomatitis|Aphthous Ulcer
**Herpes simplex infection
**[[Herpes simplex]] infection
**Coxsackie virus
**[[Coxsackie virus]]
**Tonsillitis
**Tonsillitis
**Methotrexate/chemotherapy toxicity
**[[methotrexate toxicity|Methotrexate]]/chemotherapy toxicity


=Acute Dyspnea=
===Acute Dyspnea===
*Primary Lung
{{SOB DDX}}
**Pneumonia (bacterial and viral)
**Pneumonitis
**Pulmonary Embolism
**Pneumothorax
**Malignancy
**Mucus plugging
**Reactive airway disease
**Aspiration
**Pleural Effusion
*Primary Cardiac
**Congestive Heart Failure
**Myocardial infarction
**Valvular disease
**Aortic Stenosis or regurgitation
**Pericardial Effusion
**Myocarditis/Pericarditis
*Primary Metabolic
**Sepsis
**Metabolic Acidosis


==Evaluation==
==Evaluation==
Note: patients who present ''in extremis'' after an ingestion will not survive regardless of management and should be treated palliatively.
===Workup===
 
*Labs
ABC's
**CBC
*Airway: consider early aggressive intubation for any respiratory distress or large (>100mL) ingestions
**BMP
*Breathing: CXR, O2. Avoid aggressive oxygen therapy if not necessary due to increased free radical production
**[[LFTs]] and coagulation tests
*Circulation: may develop early shock and require aggressive inotropic support
**[[VBG]] or [[ABG]]
 
**[[UA]]: high concentrations of paraquat in the urine will cause it to appear blue
Laboratory Evaluation
**Urine dithionate test:
*CBC
***Add 1cc of 1% sodium dithionate (hematology labs have this solution) to 10mL urine
*BMP
***Blue color change indicates presence of paraquat
*LFTs and coagulation tests
*Imaging
*VBG or ABG
**[[CXR]]
*UA: high concentrations of paraquat in the urine will cause it to appear blue
**[[EKG]]
**consider CT if stable to evaluate for perforation/[[mediastinitis]]


Diagnostics
===Diagnosis===
*CXR
*Based on urine test
*EKG
*consider CT if stable to evaluate for perforation/mediastinitis


==Management==
==Management==
''Patients who present in extremis after an ingestion will not survive regardless of management and should be treated palliatively. Large >50mL ingestions of paraquat are universally fatal. Aggressive resuscitation is futile. ''
===Resuscitation===
*Airway: consider early aggressive [[intubation]] for any respiratory distress or large (>100mL) ingestions
*Breathing: [[CXR]], [[O2]]
**Avoid aggressive oxygen therapy unless severe [[hypoxia]] due to increased free radical production
*Circulation: may develop early shock and require aggressive [[pressors|inotropic]] support


Decontamination
===Decontamination===
*Paraquat is absorbed transdermally. Unprotected first responders and healthcare workers are at risk
*Paraquat is absorbed transdermally. Unprotected first responders and healthcare workers are at risk
*Remove clothing and wash patient's skin if spillage or obvious skin involvement present
*Remove clothing and wash patient's skin if spillage or obvious skin involvement present
*Consider activated charcoal or Fuller's Earth if within 1-2 hrs of ingestion
*Consider [[activated charcoal]] or Fuller's Earth if within 1-2 hrs of ingestion
*Consider NG tube for administration of AC
*Consider [[NG tube]] for administration of [[activated charcoal]]
**Must weigh risks as NGT placement can exacerbate caustic injury
**Must weigh risks as NGT placement can exacerbate caustic injury


Resuscitation
===Supportive Care===
*Large >50mL ingestions of paraquat are universally fatal. Aggressive resuscitation is futile.
*ABCs as noted above; avoid supplemental O2 unless severe hypoxia present
 
Supportive Care
*IV fluids: patients often 2-3L fluid down
*IV fluids: patients often 2-3L fluid down
*Pain control
*Pain control


Antidotes/Additional Therapies
===Antidotes/Additional Therapies===
*Some centers administer glucocorticoids (typically dexamethasone 6mg-10mg IV q6h)
*Some centers administer [[glucocorticoids]] (typically [[dexamethasone]] 6mg-10mg IV q6h)
*Consider NAC, Vit C, other free radical scavengers in consultation with toxicologist or poison control
*Consider [[NAC]], vitamin C, other free radical scavengers in consultation with toxicologist or poison control
*No role for extracorporeal elimination (hemodialysis, hemoperfusion, CRRT)
*No role for extracorporeal elimination ([[hemodialysis/Hemoperfusion]], CRRT)


==Disposition==
==Disposition==
 
*If small/trivial exposure and patient asymptomatic at 6 hours, unlikely to manifest a significant toxicity
*Any symptomatic exposure requires admission for close hemodynamic monitoring and supportive care


==See Also==
==See Also==
 
*[[Toxicology (main)]]


==External Links==
==External Links==

Latest revision as of 00:22, 22 October 2020

Background

  • Paraquat is an herbicide that has a rapid and large distribution and can be fatal even with small ingestions. It has a high case-fatality rate (>50%)[1] which makes it a frequent means of suicide in the developing world, as well as a dangerous accidental occupational exposure.
  • Paraquat exerts its toxic effects via multiple proposed mechanisms, including lipid peroxidation and generation of reactive oxygen species, direct mitochondrial toxicity, and apoptosis.

Clinical Features

Paraquat Tongue (Credit: wikitox.org)

Overall, pulmonary and renal toxicities predominate and are the primary cause of mortality. GI toxicity is nearly universal and is probably an under-recognized cause of mortality secondary to erosion and perforation.

Differential Diagnosis

Toxic Ingestion

Oral Burns/Mucositis

Acute Dyspnea

Acute dyspnea

Emergent

Non-Emergent

Evaluation

Workup

  • Labs
    • CBC
    • BMP
    • LFTs and coagulation tests
    • VBG or ABG
    • UA: high concentrations of paraquat in the urine will cause it to appear blue
    • Urine dithionate test:
      • Add 1cc of 1% sodium dithionate (hematology labs have this solution) to 10mL urine
      • Blue color change indicates presence of paraquat
  • Imaging

Diagnosis

  • Based on urine test

Management

Patients who present in extremis after an ingestion will not survive regardless of management and should be treated palliatively. Large >50mL ingestions of paraquat are universally fatal. Aggressive resuscitation is futile.

Resuscitation

  • Airway: consider early aggressive intubation for any respiratory distress or large (>100mL) ingestions
  • Breathing: CXR, O2
    • Avoid aggressive oxygen therapy unless severe hypoxia due to increased free radical production
  • Circulation: may develop early shock and require aggressive inotropic support

Decontamination

  • Paraquat is absorbed transdermally. Unprotected first responders and healthcare workers are at risk
  • Remove clothing and wash patient's skin if spillage or obvious skin involvement present
  • Consider activated charcoal or Fuller's Earth if within 1-2 hrs of ingestion
  • Consider NG tube for administration of activated charcoal
    • Must weigh risks as NGT placement can exacerbate caustic injury

Supportive Care

  • IV fluids: patients often 2-3L fluid down
  • Pain control

Antidotes/Additional Therapies

Disposition

  • If small/trivial exposure and patient asymptomatic at 6 hours, unlikely to manifest a significant toxicity
  • Any symptomatic exposure requires admission for close hemodynamic monitoring and supportive care

See Also

External Links

References

  1. ↑ Gawaramanna I, Buckley N. Medical management of paraquat ingestion. Br J Clin Pharmacol. 2011;72(5):745–757
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