Paraquat toxicity: Difference between revisions

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==Differential Diagnosis==
==Differential Diagnosis==
=Toxic Ingestion=
*[https://wikem.org/wiki/Caustic_ingestion Caustic Ingestion]
*[https://wikem.org/wiki/Toxic_alcohols Toxic Alcohols]
*[https://wikem.org/wiki/Ingested_foreign_body Foreign Body Ingestion]


=Oral Burns/Mucositis=
*[https://wikem.org/wiki/Burns Burns]
*Infectious Causes
**Aphthous Ulcer
**Herpes simplex infection
**Coxsackie virus
**Tonsillitis
**Methotrexate/chemotherapy toxicity
=Acute Dyspnea=
*Primary Lung
**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==

Revision as of 00:14, 18 July 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 underrecognized cause of mortality secondary to erosion and perforation.

Differential Diagnosis

Toxic Ingestion

Oral Burns/Mucositis

  • Burns
  • Infectious Causes
    • Aphthous Ulcer
    • Herpes simplex infection
    • Coxsackie virus
    • Tonsillitis
    • Methotrexate/chemotherapy toxicity

Acute Dyspnea

  • Primary Lung
    • 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

Note: patients who present in extremis after an ingestion will not survive regardless of management and should be treated palliatively.

ABC's

  • Airway: consider early aggressive intubation for any respiratory distress or large (>100mL) ingestions
  • Breathing: CXR, O2. Avoid aggressive oxygen therapy if not necessary due to increased free radical production
  • Circulation: may develop early shock and require aggressive inotropic support

Laboratory Evaluation

  • CBC
  • BMP
  • LFTs and coagulation tests
  • VBG or ABG
  • UA: high concentrations of paraquat in the urine will cause it to appear blue

Diagnostics

  • CXR
  • EKG
  • consider CT if stable to evaluate for perforation/mediastinitis

Management

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 AC
    • Must weigh risks as NGT placement can exacerbate caustic injury

Resuscitation

  • 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
  • Pain control

Antidotes/Additional Therapies

  • 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
  • No role for extracorporeal elimination (hemodialysis, hemoperfusion, CRRT)

Disposition

See Also

External Links

References

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