Acute radiation syndrome

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Background

  • Also called radiation poisoning, radiation toxicity, or radiation sickness.
  • Acute illness caused by exposure to high doses (at least 1 Gy)[1] of ionizing radiation over a short period of time.
    • 1 Gray (Gy) = 100 rads
  • Generally requires exposure of whole body (or most of the body)
  • Fast-replicating cell lines most affected - GI, lymphohematopoietic, spermatocytes
  • Healthcare providers should use isolation precautions and decontamination procedures
    • Geiger counters may be useful in identifying contamination

Clinical Features

Clinical Syndromes[1][2]

Bone Marrow Syndrome

  • Clinical syndrome seen at doses >100-200 rad (1-2 Gy)
    • Smaller doses cause clinically insignificant pancytopenia)
  • Lymphocytes depleted first, then granulocytes, platelets, and RBCs
    • Lymphocyte depletion is predictable based on dose
  • Death usually secondary to infection or hemorrhage and poor healing
    • Doses >350 rad fatal within several months if untreated

Gastrointestinal (GI) Syndrome

  • Syndrome occurs at 600-1000 rad (6-10 Gy)
  • Characterized by abdominal pain, nausea, vomiting, diarrhea, ileus
  • Death occurs within weeks secondary to multiorgan failure and sepsis if untreated

Cardiovascular (CV)/Central Nervous System (CNS) Syndrome

  • Syndrome occurs at >1000-2000 rad (10-20 Gy)
    • At this dose, vomiting is suppressed
    • Characterized by ALOC, dizziness, papilledema, ↓ DTRs, ataxia, coma
  • Doses >3500 rad (35 Gy) damage large blood vessels → cardiovascular failure, cerebral edema
  • Doses >5000 rad (50 Gy) cause death within 48 hours

Clinical Course[1][2]

  • Each ARS syndrome typically progresses through 4 stages of disease

Prodromal Stage

  • Characterized by nausea and vomiting
    • Other symptoms include: malaise, fever, conjunctivitis
    • Doses over 1000 rad (10 Gy), vomiting is not seen in early symptoms
  • Occurs within 48h-6d of exposure (at higher doses, can begin within minutes)
  • Lasts up to 2 days

Latent Stage

  • Short period of symptom improvement
  • Lasts several days to 1 month

Manifest Illness Stage

  • Manifestation of symptoms of clinical syndromes
  • Severity based on, among other things:
    • Overall dose
    • Irradiated body volume
    • Comorbidities and overall health status
    • Age
  • Characterized by significant immunosuppression
  • Lasts for days to months

Recovery or Death

  • If patient survives manifest illness stage, recovery is slow (weeks to years)
  • If lethal dose received, death can occur within days (very high, rapid doses) or may be delayed up to several months
  • Doses over 1000 rad (10 Gy) are uniformly fatal

Differential Diagnosis

Mass casualty incident

Nausea and vomiting

Critical

Emergent

Nonemergent

Evaluation

  • Clinical diagnosis, based on history and physical
  • Absolute lymphocyte count is the best prognosticator at 48hrs post-exposure[3] (<1500 is abnormal and indicates a significant exposure)

Management

  • Aggressive supportive care is hallmark of ED management
  • Potassium iodide as thyroid protectant, at 130mg qd for adults, until radiation exposure ceases[4]

Disposition

  • Admit

See Also

References

  1. ↑ 1.0 1.1 1.2 Waselenko JK, MacVittie TJ, Blakely WF, et al. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med. 2004 Jun 15;140(12):1037-51.
  2. ↑ 2.0 2.1 Donnelly EH1, Nemhauser JB, Smith JM, et al. Acute radiation syndrome: assessment and management. South Med J. 2010 Jun;103(6):541-6.
  3. ↑ Colwell CB: Radiation injuries, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2013, (Ch) 146: pp 1945-1951.
  4. ↑ New York State Potassium Iodide (KI) and Radiation Emergencies: Fact Sheet. https://www.health.ny.gov/environmental/radiological/potassium_iodide/fact_sheet.htm.
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