Summary of preparatory reading for MUHC ED Disaster Preparedness Course for Residents

1. Adapted from Donnelly et al, Acute Radiation Syndrome: Assessment and Management, Southern Medical Journal, 103:6, June 2010
Acute Radiation Syndrome (ARS)
Few clinicians will experience this first hand, therefore theoretical preparation is key to handling patients with radiation
exposure should a disaster arise. There are no pathognomonic signs or symptoms so it is difficult to diagnose without an
obvious history of exposure.
Pathophysiology
 More actively replicating cells are most sensitive to radiation.
 Tissues affected most: gonads>bone marrow>GI>neuro>connective tissue>muscle>bone
3 classic ARS syndromes
There is clinical overlap between the syndromes. Damage to increasingly radio-resistant cells is a marker of higher
absorbed dose and clinical severity.
Hematopoietic/Bone Marrow syndrome
 Occurs with exposure >200 rad
 Lymphocytes depleted first, followed by granulocytes and platelets within days
 Red cells less sensitive so rapid anemia is unusual (i.e. search for other causes e.g. bleeding)
 Death occurs within weeks-months due to infection from impaired immunity or bleeding
Gastrointestinal syndrome
 Occurs with exposures between 600 – 1000 rad
 Abrupt onset within hours of n°/v°, anorexia and crampy abdo pain
 Vomiting suppressed >1000 rad
 Diarrhea is an ominous sign
 Death occurs from overwhelming sepsis, multi-organ failure, bleeding within weeks
Neurovascular syndrome
 At doses >1000 rad:“fatigue syndrome”: fever, headache, then altered reflexes, dizziness, confusion,
disorientation, ataxia, and loss of consciousness with increasing dose
 At doses >3500 rad: damaged blood vessels →circulatory collapse, ↑ICP, cerebral vasculitis, meningitis
 At doses >5000 rad: death within 48h before other syndromes can manifest
Phases
All 3 syndromes have 4 phases:
 Prodromal phase: n°/v°, fever, headache, parotitis, abdominal cramping, skin erythema, conjunctivitis, and
hypotension. Usually <48h duration. More rapid time to onset with higher dose.
 Latent phase: hours to weeks of clinical improvement but stems cells are depleted.
 Manifest phase: days to months of adverse health effects of each syndrome.
 Recovery or death: recovery can take months to years. Patients exposed to very high dose die within days,
lower lethal doses cause death within weeks to months.
Farooq Khan MDCM
PGY3 FRCP-EM
McGill University
November 14
th
2011

2. Adapted from Donnelly et al, Acute Radiation Syndrome: Assessment and Management, Southern Medical Journal, 103:6, June 2010
Assessment
Absolute lymphocyte count
 Easy and quick, esp. In mass casualty
 CBC q4h for first 8h, then q6h for next 40-48h
 Initially low or progressively falling count is highly
suggestive of high dose radiation exposure (see
nomogram)
Time to vomiting
Caveats about time to vomiting
 Non specific
 Suppressed >1000 rad
 50% sensitive at 200-300 rad
 80-90% sensitive at 500-600 rad
Gold standard of dicentric chromosome assay is not offered at most sites and has long turnaround time (weeks)
Management
Prodromal phase
Regardless of triage category:
 History and physical examination
 Removal of external contamination
 Dose estimation
 Symptomatic and supportive care (including
psychological support of the patient and family)
 Replacement of fluids and electrolytes
Latent phase
Estimate following factors that impact prognosis
 Age and underlying health status
 Magnitude of absorbed dose
 Body volume irradiated
 Illness severity
 Concomitant infection, physical trauma, or
burn/dermal injury
Manifest phase
 Triage to minimal care, aggressive supportive care, or palliative care depending on prognosis
 Transfer of individuals with hematopoietic syndrome to tertiary care centers specializing in the care of
pancytopenic patients (incl. ID and Heme for febrile neutropenia)
 ANC<0.5×109
leads to higher infection rates
 G-CSF (Neupogen) and GM-CSF can stimulating spared or resistant stem cells into repopulating bone marrow.
Stem cell transplants can also be done
Radiation emergency medicine consultation services provided by the Radiation Emergency Assistance Center/Training
Site (REAC/TS) with physicians and health physicists available 24/7 at 865-576-1005.
Figure 1 Andrews nomogram Curves 1 to 4 correspond
roughly to the following whole-body doses: curve 1: 3.1 Gy
(3,100 rad), curve 2: 4.4 Gy (4,400 rad), curve 3: 5.6 Gy
(5,600 rad), and curve 4: 7.1 Gy (7,100 rad)