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Toxic Syndromes

What is Toxic Syndrome and Why is Its Recognition Important?

  • Toxic syndrome is a constellation of toxic effects comprising a set of clinical fingerprints for a group of toxic chemicals.
  • Toxic syndrome recognition is important because it provides a tool for rapid detection of the suspected cause and can focus the differential diagnosis to consideration of only a few chemicals with similar toxic effects.

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What Do I Need to Do as a Physician?

  • Clinical decision making during an emergency response to a hazardous chemical accident or chemical terrorist attack can be complex and highly uncertain.
  • To do the best for the most, clinicians need a system that rapidly identifies toxicity and guides early medical decisions and antidote therapy.
  • Applying basic principles of toxicology can simplify decision making during mass exposures to toxic chemical events.
  • Identifying toxic syndromes at the bedside and using the dose-response concept to assess toxic chemical exposure can be helpful.

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Common Toxic Syndromes Observed in Mass Chemical Exposures

The toxic syndromes noted below are derived from expected clinical effects after exposure to those chemicals most often reported to be involved in accidental spills, those with likelihood of causing significant health impact upon release, and those with emergent treatments available (eg, cyanide and nerve agent poisoning).

Irritant Gas Syndrome

  • Eye, nose, and throat irritation
  • Cough
  • Wheezes
  • Shortness of breath
  • Chest pain
  • Caution: may be a delayed presentation

Ammonia, Chlorine,
Delayed presentation seen with phosgene and nitrogen dioxide

Vesicant/Blister Agent Poisoning

  • Conjunctivitis
  • Erythema
  • Sore throat
  • Cough
  • Corneal damage
  • Vesicles & bullae
  • Nausea
  • Wheezing
  • Stridor
  • Laryngeal edema
  • Acute lung injury

Sulfur mustard, Lewisite,
Phosgene oxime

Chemical Burns

  • Painful burning skin
  • Mucous membrane irritation
  • Systemic effects

Hydrochloric acid, Hydrofluoric acid, Hydrocarbon solvents such as degreasors and defatters

"Knockdown" or
Metabolic Poisoning

  • Rapid loss of consciousness
  • Seizures
  • Hypotension
  • Cardiac arrest

Cyanide, Hydrogen sulfide, Phosphine

"The Fear Factor"

  • Lightheadedness
  • Shortness of breath
  • Chest pain
  • Faint
  • Nausea
  • Sweating skin
  • Palpitations
  • Tremor

Often "fight or flight" stress response from fear of chemical exposure
CAUTION: low level exposure to toxins can resemble this response

Organophosphate Insecticide Poisoning (Pesticide Syndrome, Cholinergic Storm)

  • Pinpoint pupils
  • Eye pain
  • Shortness of breath
  • Wheezes
  • Rales
  • Sweating skin
  • Drooling
  • Tearing
  • Vomiting
  • Diarrhea
  • Fasciculations
  • Coma
  • Seizures

Organophosphate and carbamate insecticides,
Nerve agents

Acute Solvent Exposure

  • Headache
  • Lightheadedness
  • Nausea
  • Mucous membrane irritation
  • Confusion
  • Syncope

Paint thinners,
Degreasors and lubricants,
Toluene, Methylene chloride, Trichloroethylene

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Additional Considerations

  • By focusing on certain chemicals, specific diagnostic testing and empiric therapies can be rendered based on objective clinical evidence. Specifically during a mass exposure, recognition can provide a triage tool for identifying exhibiting toxic effects and also provide a common "language" so that emergency responders from the scene through to the hospital ED can clearly communicate a clinical message.
  • With the extraordinary number of chemicals in use, this tool does not apply to every chemical but to most of the commonly encountered chemicals reported in HazMat incidents. Other toxic effects caused by chemicals include hematologic injury such as methemoglobinemia or hemolysis, liver and kidney injury, and peripheral neuropathies. These less-common toxic effects may require the assistance of a medical toxicologist to guide work-up and medical management.
  • The use of toxic syndromes as a diagnostic tool is fundamental to an effective medical response. However, the degree to which the toxic symptoms present themselves depends on both the route of exposure and the dose.

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  1. Kirk MA, Deaton ML. Bringing order out of chaos: effective strategies for medical response to mass chemical exposure. Emerg Med Clin North Am. 2007 May;25(2):527-48. [PubMed Citation]
  2. Markel G, Krivoy A, Rotman E, Schein O, Shrot S, Brosh-Nissimov T, Dushnitsky T, Eisenkraft A. Medical management of toxicological mass casualty events. Isr Med Assoc J. 2008 Nov;10(11):761-6. [PubMed Citation]
  3. Clinical Care During Man-made and Natural Disasters: Triage and Medical Management of Radiological and Chemical Casualties (PDF - 8.60 MB) (James M. Madsen, MD, MPH, FCAP, FACOEM COL, MC-FS, US Army)
  4. Chemical warfare agents: an overview (NIH VideoCasting and Podcasting, 1 hour 11 minutes) (James M. Madsen, MD, MPH, FCAP, FACOEM COL, MC-FS, US Army)