Radiation Injury
Radiation injury is a time-dependent, dose-dependent multisystem syndrome that every intensivist must understand — particularly in scenarios involving:
- Nuclear accidents
- Radiotherapy complications
- Industrial exposure
- Radiological terrorism
- Accidental medical overexposure
1. Radiation Basics
Types of Ionizing Radiation
|
Type |
Penetration |
Shielding |
Clinical relevance |
|
Alpha (α) |
Low |
Paper / skin |
Dangerous if inhaled/ingested |
|
Beta (β) |
Moderate |
Plastic/aluminum |
Skin burns |
|
Gamma (γ) |
High |
Lead/concrete |
Whole body ARS |
|
Neutron |
Very high |
Hydrogen-rich materials |
Nuclear reactors |
Units
|
Parameter |
Unit |
|
Absorbed dose |
Gray (Gy) |
|
Biological effect |
Sievert (Sv) |
|
1 Gy = |
1 J/kg |
|
LD50/60 (untreated) |
~3–4 Gy |
2. Acute Radiation Syndrome (ARS)
Occurs after whole-body exposure >1 Gy.
Phases of ARS
|
Phase |
Timeline |
Features |
|
Prodromal |
Minutes–days |
Nausea, vomiting, diarrhea |
|
Latent |
Hours–weeks |
Apparent recovery |
|
Manifest illness |
Days–weeks |
Organ-specific failure |
|
Recovery / Death |
Weeks–months |
Depends on dose |
2.1 Hematopoietic Syndrome (2–6 Gy)
Pathophysiology
- Bone marrow stem cell apoptosis
- Neutropenia → sepsis
- Thrombocytopenia → bleeding
Timeline
- Lymphocyte fall within 24–48 hrs (earliest marker)
- Pancytopenia by 2–3 weeks
ICU Features
- Septic shock
- Mucosal bleeding
- DIC-like picture
Management
|
Intervention |
Role |
|
Reverse isolation |
Infection prevention |
|
Broad spectrum antibiotics |
Early empiric |
|
G-CSF (Filgrastim) |
Speeds neutrophil recovery |
|
Platelet transfusion |
If <10k or bleeding |
|
Stem cell transplant |
If dose 6–10 Gy |
2.2 Gastrointestinal Syndrome (6–10 Gy)
Mechanism
- Crypt cell destruction
- Loss of mucosal barrier
- Bacterial translocation
Clinical
- Severe diarrhea
- GI bleeding
- Electrolyte collapse
- Sepsis
Mortality
Usually fatal within 2 weeks without advanced care.
ICU Management
- Aggressive fluids
- TPN
- Broad antibiotics
- Barrier nursing
- Vasopressors as needed
2.3 Neurovascular (CNS) Syndrome (>20–30 Gy)
Features
- Confusion
- Ataxia
- Seizures
- Coma
- Death within 48 hours
Mechanism: Cerebral edema + endothelial destruction.
No effective treatment. Supportive only.
3. Cutaneous Radiation Injury (CRI)
Stages
|
Dose |
Finding |
|
2–5 Gy |
Erythema |
|
5–10 Gy |
Dry desquamation |
|
10–20 Gy |
Moist desquamation |
|
>25 Gy |
Necrosis |
Management
- Topical steroids
- Debridement
- Pain control
- Plastic surgery
- Hyperbaric oxygen (selected cases)
4.Combined Radiation Injury (CRI)
Radiation + trauma/burns = worse mortality
Mechanism:
- Immune suppression
- Delayed wound healing
- High infection rate
Important disaster triage principle:
Patients with severe trauma + >8 Gy exposure → poor prognosis
5. Diagnosis in ICU
Early Markers
|
Test |
Interpretation |
|
Absolute lymphocyte count |
Rapid fall = higher dose |
|
Chromosomal aberration assay |
Gold standard biodosimetry |
|
Time to vomiting |
<1 hr = >4 Gy |
6. Decontamination Protocol (ICU Entry)
- Remove clothing (removes 90% contamination)
- Wash with soap + water
- Isolate radioactive waste
- PPE for staff
Irradiated patients are NOT radioactive.
7. Specific Antidotes
|
Agent |
Exposure |
Antidote |
|
Radioiodine |
Nuclear reactor |
Potassium iodide |
|
Cesium |
Dirty bomb |
Prussian blue |
|
Plutonium |
Industrial |
DTPA |
8. ICU Management Algorithm
- ABC stabilization
- Trauma management first
- Estimate dose
- CBC serial monitoring
- Start G-CSF if lymphocyte drop
- Early antibiotics
- Manage organ failure
- Consider stem cell transplant
9. Prognosis by Dose
|
Dose (Gy) |
Syndrome |
Survival |
|
<2 |
Mild |
Good |
|
2–6 |
Hematopoietic |
Survivable with ICU |
|
6–10 |
GI |
Guarded |
|
>20 |
CNS |
Fatal |
10. Radiation Injury in Oncology ICU
Seen in:
- Head & neck RT mucositis
- Radiation pneumonitis
- Radiation cystitis
- Radiation myelopathy
11. Radiation Pneumonitis
Timeline
1–6 months post-radiotherapy
Features
- Dry cough
- Dyspnea
- Hypoxia
- Ground glass opacities on CT
Treatment
- High-dose steroids
- Oxygen
- Mechanical ventilation (if ARDS)
12. Differences: Radiation vs Thermal Burns
|
Feature |
Radiation |
Thermal |
|
Delayed onset |
Yes |
No |
|
Progressive |
Yes |
No |
|
Systemic ARS |
Yes |
No |
|
DNA damage |
Yes |
No |