Radiation Injuries & Radiological Disasters
Comprehensive emergency evaluation and protocolized management of ionizing radiation exposures and radiological disasters: differentiating external irradiation, radioactive contamination (external vs. internal), and contaminated wounds; the four phases of Acute Radiation Syndrome (ARS: prodromal, latent, manifest illness, recovery/death); the three major organ sub-syndromes (Hematopoietic [>= 2 Gy], Gastrointestinal [>= 6–8 Gy], and Cerebrovascular [>= 20–30 Gy]); the critical 48-hour Absolute Lymphocyte Count (ALC) biodosimetry kinetics (Andrews nomogram); medical countermeasures (Potassium Iodide [KI] for radioactive iodine-131, Prussian blue for cesium/thallium, Ca-DTPA/Zn-DTPA for plutonium, G-CSF/Filgrastim for marrow rescue); and ED decontamination hot zones.
Resuscitation Quick Actions • First 2 Minutes
Irradiation vs Contamination
Irradiation: patient is NOT radioactive (safe to touch immediately); Contamination: radioactive dust on body (strip clothes to remove 90%)
Resuscitation Trumps Decon
Treat tension pneumothorax, massive hemorrhage, and airway loss FIRST; never delay trauma resuscitation for radiation survey
48-Hour Lymphocyte Count
Absolute Lymphocyte Count (ALC) is the gold-standard biodosimeter: ALC < 1,000 at 48h = severe ARS; ALC < 500 = lethal exposure (> 5 Gy)
Potassium Iodide (KI) Dose
130 mg PO daily for adults (pregnant/lactating 130 mg; peds 65 mg; infants 16 mg); must be given within 4–6h to block Iodine-131 in thyroid
Prussian Blue (Radiogardase)
3 grams PO TID; binds radioactive Cesium-137 and Thallium in gut to prevent enterohepatic recirculation
G-CSF/Filgrastim
5 mcg/kg/day SC immediately for any whole-body exposure > 2 Gy to accelerate granulocyte and neutrophil recovery
Bottom-Line Clinical Pearl
Radiological emergencies require strict separation between External Irradiation (patient was exposed to radiation waves, but emits ZERO radiation; they pose NO THREAT to healthcare workers) and Radioactive Contamination (patient carries radioactive particulate matter on skin/clothes or internally; requires decontamination). The primary rule: LIFE-SAVING MEDICAL RESUSCITATION ALWAYS TAKES PRIORITY OVER DECONTAMINATION. Acute Radiation Syndrome (ARS) occurs following whole-body penetrating exposure > 1–2 Gray (Gy). The single most important early biological dosimeter is the ABSOLUTE LYMPHOCYTE COUNT (ALC) at 48 hours post-exposure: lymphocytes are the most radiosensitive cells in the human body; a drop in ALC < 1,000/mcL at 24–48 hours indicates significant ARS, while ALC < 500/mcL indicates lethal marrow destruction. Specific countermeasures: (1) Potassium Iodide (KI 130 mg PO) blocks thyroid uptake of radioactive Iodine-131, (2) Prussian Blue binds Cesium-137, (3) Ca-DTPA chelates Plutonium, and (4) G-CSF (Filgrastim 5 mcg/kg/day) rescues hematopoietic marrow.
| Radiation Exposure Category | Mechanism & Source | Hazard to Resuscitation Staff | Emergency Management Actions |
|---|---|---|---|
| External Irradiation | High-energy penetrating gamma rays, X-rays, or neutrons pass completely through the patient's body | ZERO HAZARD. The patient emits no radiation and is NOT radioactive. Touching or resuscitating the patient carries zero risk to staff. | Provide routine medical and trauma care. No decontamination required. |
| External Contamination | Radioactive dust, liquids, or particulate matter settle on the patient's skin, hair, or clothing (e.g., 'dirty bomb'/radiological dispersal device) | Low-to-moderate hazard. Radioactive particulates can transfer to staff or hospital surfaces. | Strip and bag all clothing immediately (removes 90% of external contamination). Copiously wash skin with warm water and mild soap. Resuscitate life threats first! |
| Internal Contamination | Radioactive isotopes are inhaled, ingested, or absorbed through open puncture wounds | Low direct hazard to staff; biological fluids (urine, vomitus, blood) contain radioactive material. | Administer isotope-specific decorporation antidotes (Prussian Blue, Potassium Iodide, Ca-DTPA); collect urine/stool for bioassay. |
Acute Radiation Syndrome (ARS) occurs after significant whole-body penetrating exposure ($> 1\text{ to }2\text{ Gray [Gy]} = 100\text{ to }200\text{ rads}$) delivered at a high dose rate:
| Organ Sub-Syndrome | Radiation Dose Threshold | Pathophysiologic Timeline | Manifest Illness & Survival |
|---|---|---|---|
| Hematopoietic Syndrome | $\ge 2\text{ Gy}$ (200 rads) | Prodrome of nausea/vomiting at 6–12h; latent phase 1 to 3 weeks; manifest pancytopenia at 2–4 weeks | Destruction of bone marrow hematopoietic stem cells $\rightarrow$ severe lymphopenia, neutropenia, and thrombocytopenia $\rightarrow$ fatal sepsis and hemorrhage. Survival is possible with supportive care, reverse isolation, blood products, and G-CSF (Filgrastim 5 mcg/kg/day). |
| Gastrointestinal Syndrome | $\ge 6\text{ to }8\text{ Gy}$ (600–800 rads) | Rapid prodrome of severe vomiting/diarrhea within 1–2 hours; brief latent phase (3–5 days); manifest illness at 5–10 days | Total mitotic arrest and sloughing of intestinal crypt stem cells $\rightarrow$ loss of mucosal barrier, bloody intractable diarrhea, massive fluid third-spacing, and overwhelming enteric bacteremia. Mortality is > 90%. |
| Neurovascular/Cerebrovascular | $\ge 20\text{ to }30\text{ Gy}$ (2,000–3,000 rads) | Hyperacute onset (within minutes): burning sensation, severe vomiting, ataxia, seizures, disorientation, coma | Direct endothelial microvascular collapse, acute cerebral edema, and cardiovascular shock. Universally fatal within 24 to 72 hours; manage with aggressive palliative comfort care. |
Circulating lymphocytes are the most exquisitely radiosensitive cells in the human body, undergoing rapid apoptosis within hours of irradiation. Serial CBCs with differential drawn every 6 hours for the first 48 hours provide the most accurate clinical biodosimeter to calculate radiation dose (Andrews Nomogram):
| 48-Hour Absolute Lymphocyte Count (ALC) | Estimated Radiation Dose Received | Clinical Prognosis & Injury Severity |
|---|---|---|
| $1,500\text{ to }3,000\text{ cells/mcL}$ | $< 1\text{ Gy}$ (Mild/Subclinical) | Minimal injury; outpatient observation. |
| $1,000\text{ to }1,499\text{ cells/mcL}$ | $1\text{ to }2\text{ Gy}$ (Moderate) | Moderate hematopoietic suppression; hospital admission. |
| $500\text{ to }999\text{ cells/mcL}$ | $2\text{ to }4\text{ Gy}$ (Severe) | Severe bone marrow aplasia; G-CSF, barrier isolation, broad-spectrum antibiotics. |
| $100\text{ to }499\text{ cells/mcL}$ | $4\text{ to }8\text{ Gy}$ (Very Severe) | Critical pancytopenia and GI mucosal breakdown; specialized burn/radiation center. |
| $< 100\text{ cells/mcL}$ (at 24–48 hours) | $> 8\text{ Gy}$ (Lethal Exposure) | Lethal dose; gastrointestinal and neurovascular collapse. |
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