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Approach to the Critical Patient
Initial priorities and scene safety
Immediate priorities
Airway compromise triggers
Stridor
Facial burns
Oropharyngeal edema
Altered mental status
Breathing failure triggers
SpO2 < 90% on supplemental oxygen
Rising PaCO2 in mmHg
Circulatory instability triggers
SBP < 90 mmHg
Signs of shock
Concurrent trauma and burns as primary determinants of early mortality
Trauma life support sequence before decontamination
Hemorrhage control before radiologic survey
Staff protection
Time distance shielding principles
Minimize time near source
Maximize distance
Use shielding when feasible
PPE baseline
Double gloves
Fluid resistant gown
Eye protection
Surgical mask or respirator based on airborne risk
Dosimetry and exposure limits per institutional plan
Personal dosimeter assignment if available
Rotation of staff during prolonged care
Patient flow control
Designated hot warm cold zones
Hot zone for contaminated clothing and initial survey
Warm zone for decontamination
Cold zone for definitive care
Isolation of belongings
Bag and label clothing
Secure personal items for radiation safety
Contamination and decontamination in ED
Contamination triage
External contamination versus exposure distinction
Contamination as removable radioactive material
Exposure as radiation dose without residual material
Immediate decontamination triggers
Visible particulate on skin or hair
Positive survey over skin or wounds
Decontamination not delaying life saving interventions
Airway and hemorrhage control first
Rapid gross decon during resuscitation only if feasible
Decontamination steps
Clothing removal
Removal of all clothing reduces contamination burden substantially
Bagging and labeling for radiation safety chain
Skin and hair
Lukewarm water and mild soap
Gentle technique to avoid skin abrasion
Repeat survey guided decon
Wounds
Irrigation with saline
Removal of foreign material
Dressing after survey confirmed reduction
Eye and mouth
Copious irrigation if particulate exposure
Avoid ingestion of rinse water
Radiologic survey and contamination documentation
Survey meter or portal monitor use if available
Baseline background reading documentation
Head to toe survey pattern
Contaminated wound as highest priority source control
Wound survey before closure
Repeat survey after irrigation
Early risk stratification for acute radiation syndrome
Rapid severity indicators
Time to emesis after event
Early vomiting associated with higher whole body dose
No vomiting by 8 to 10 hours suggests dose likely < 1 Gy
Absolute lymphocyte count trajectory
Serial ALC decline over first 48 hours for severity estimate
Early severe lymphopenia suggesting higher dose
Cutaneous findings
Early erythema
Epilation timing
Moist desquamation
Neurovascular signs
Early confusion
Ataxia
Refractory hypotension
Consultation and escalation triggers
Radiation safety officer notification
Any confirmed contamination
Unknown source event with multiple patients
Regional poison center or radiation medical support
Suspected internal contamination
Need for decorporation agents
Burn center or trauma center activation
Combined injury with burns
Major trauma
Hematology and transplant network early contact
Suspected hematopoietic ARS >= 2 Gy
Anticipated marrow failure
History
Exposure characterization
Event details
Radiation type and source
Medical source
Industrial source
Nuclear reactor incident
Radiological dispersal device
Time course
Time of event
Duration of exposure
Time since exposure
Distance and shielding
Proximity to source
Barriers and sheltering
Multiple victims and clustering
Similar symptoms among others
Shared location exposure
Contamination risk
Dust smoke or aerosol exposure
Inhalation risk
Eye and mucosal exposure risk
Ingestion risk
Food and water sources
Hand to mouth exposure
Wounds in contaminated environment
Open injuries at event
Embedded particulate
Symptom timeline and classic phases
Prodromal symptoms
Nausea
Vomiting onset time
Diarrhea
Fatigue
Headache
Latent phase indicators
Symptom improvement after prodrome
Return of appetite
Manifest illness domain symptoms
Hematopoietic
Fever
Sore throat
Bleeding
Gastrointestinal
Persistent diarrhea
Abdominal pain
Dehydration
Cutaneous
Erythema timing
Blistering
Pain out of proportion
Neurovascular
Confusion
Ataxia
Seizure
Risk factors and modifiers
Patient factors
Age extremes
Pregnancy status
Immunosuppression
Baseline marrow disease
Combined injury
Thermal burns
Blast trauma
Chemical exposure
Smoke inhalation
Physical Exam
Primary survey focused findings
Airway and breathing
Facial burns and soot
Hoarseness
Oropharyngeal edema
Respiratory distress
Tachypnea
Hypoxia
Circulation
Shock markers
Cool clammy skin
Delayed capillary refill
Hemorrhage indicators
External bleeding
Petechiae or ecchymoses
Neurologic status
GCS trend
Rapid decline suggesting high dose or alternate cause
Focal deficits suggesting trauma or stroke
Radiation specific examination
Cutaneous radiation injury
Early erythema
Sharply demarcated fields
Burning pain or pruritus
Epilation
Patchy hair loss distribution
Timing after event
Blistering and ulceration
Moist desquamation
Necrosis signs
Infection and bleeding
Oropharyngeal ulcers
Mucositis
Thrush
Skin and line infection signs
Cellulitis
Purulence
Bleeding stigmata
Gingival bleeding
Melena or hematochezia
PITFALLS
Misattribution risks
Vomiting from anxiety pain or head injury
Diarrhea from infection or toxins
Under recognition risks
Latent phase appearing well despite high dose
Localized radiation injury with minimal systemic symptoms
Differential Diagnosis
Life threatening mimics and co exposures
Toxidromes and chemical exposures
Organophosphate poisoning ICD-10 T60
SLUDGE features
Bradycardia
Cyanide toxicity ICD-10 T65.0
Severe lactic acidosis
Soot exposure
Carbon monoxide poisoning ICD-10 T58
Headache
Altered mental status
Sepsis and gastroenteritis
Sepsis ICD-10 A41
Fever and hypotension
Elevated lactate
Viral gastroenteritis ICD-10 A08
Vomiting and diarrhea cluster
Trauma and burns
Traumatic brain injury ICD-10 S06
Vomiting and confusion
Thermal burn ICD-10 T20 to T32
Hypovolemia
Pain
Radiation related syndromes and patterns
Acute radiation syndrome SNOMED CT concept
Hematopoietic syndrome
Neutropenia
Thrombocytopenia
Gastrointestinal syndrome
Severe diarrhea
Electrolyte derangements
Neurovascular syndrome
Early neurologic collapse
Cardiovascular failure
Localized radiation injury
Cutaneous radiation injury
Delayed ulceration
Progressive fibrosis
Radiation cataract
Eye pain and photophobia
Delayed lens changes
Laboratory Tests
Core labs for ARS and combined injury
Baseline evaluation
CBC with differential
Absolute lymphocyte count for early biodosimetry
Neutrophil nadir prediction with serial trends
CMP with electrolytes
Diarrhea related hypokalemia
Renal function for chelator dosing
Lactate in mmol/L
Shock marker
Sepsis screening
Coagulation studies
Bleeding risk evaluation
DIC in severe combined injury
Serial trend strategy
CBC frequency
Every 4 to 6 hours for first 24 hours when dose uncertain
Daily or more frequent based on trajectory
ALC kinetics
Declining ALC over 48 hours supporting higher dose estimation
Stabilizing ALC supporting lower dose
Infection and supportive care labs
Neutropenic fever workup
Blood cultures
Peripheral and line if present
Before antibiotics when feasible
Urinalysis and culture
Urinary symptoms
Indwelling catheter
Chest imaging correlation
Respiratory symptoms
Hypoxia
Bleeding and transfusion planning
Type and screen
Anticipated platelet transfusions
Anticipated RBC transfusions
Fibrinogen
Consumptive coagulopathy screening
Specialized radiologic injury testing
Biodosimetry support tests
Cytogenetic dicentric chromosome assay
Dose estimation reference standard where available
Utility window days to weeks
Chromosome translocation assays
Longer term dose reconstruction
Not for acute triage
Internal contamination assessment
Nasal swabs
Screening for inhaled radioactive particulate
Not quantitative dose measure
Urine and fecal bioassay
Specific radionuclide identification
Serial collection for kinetics
Diagnostic Tests
Scoring Systems
Triage based on clinical and lab surrogates
Time to emesis based categories
Earlier onset associated with higher dose
No emesis by 8 to 10 hours suggests dose likely < 1 Gy
Lymphocyte depletion kinetics
Serial ALC trend within first 48 hours as severity estimator
Marked early decline supporting higher dose
METREPOL style organ involvement grading
Hematopoietic grade by cytopenias
GI grade by diarrhea and dehydration
Combined injury prognostication
Burn plus radiation dose synergy
Higher infection risk at any neutropenia
Worse survival at similar dose with burns
MRI
MRI role
Limited utility for ARS diagnosis
ARS clinical and laboratory diagnosis
MRI reserved for complications
Neurologic evaluation when trauma excluded
Brain MRI for persistent deficits
Spinal MRI for myelopathy
MRI constraints
Unstable patient limitation
Monitoring constraints in scanner
Need for airway control
Contamination control
Decontamination before MRI suite
Radiation safety clearance
CT
CT indications
Trauma evaluation
Head CT for altered mental status with trauma concern
CT chest abdomen pelvis for suspected internal injury
Complication evaluation
CT abdomen pelvis for severe abdominal pain and ileus
CT chest for suspected pneumonia in neutropenia
CT operational considerations
Contamination management
Gross decon before transport
Coverings to limit scanner contamination
Radiation from CT not a clinical driver in mass casualty exposure context
Diagnostic yield prioritized when indicated
Avoid delay of necessary imaging
Ultrasound
POCUS applications
Shock and trauma
FAST or eFAST for free fluid or pneumothorax
Cardiac POCUS for tamponade
Vascular access
Ultrasound guided peripheral or central access
Line placement in PPE constraints
POCUS infection support
Lung ultrasound
Consolidation patterns
Pleural effusion
Soft tissue ultrasound
Abscess detection
Cellulitis differentiation
Disposition
Level of care decisions
Immediate admission criteria
Suspected whole body dose >= 2 Gy
Significant early vomiting
Rapid ALC decline
Any neutropenic fever
Temp >= 38.3 C once
Temp >= 38.0 C sustained 1 hour
Combined injury
Major burns
Major trauma
ICU criteria
Hemodynamic instability
Vasopressor requirement
Rising lactate in mmol/L
Severe GI syndrome
Refractory dehydration
Electrolyte collapse
Neurovascular syndrome features
Early severe confusion
Seizure
Transfer criteria
Need for burn center
Partial thickness burns > 10% TBSA
Airway burns
Need for marrow failure management center
Anticipated prolonged neutropenia
Need for CSF supply coordination
Need for radiation specialty support
Internal contamination requiring decorporation
Complex wound contamination
Discharge criteria
Low risk features
No significant symptoms after observation window
No vomiting
No diarrhea
Normal exam
No burns or trauma requiring admission
No concerning skin findings
Low risk lab features
CBC reassuring
No lymphopenia trend on repeat testing when obtained
No cytopenias
Follow up plan established
Return precautions
Fever
Bleeding
Outpatient repeat CBC timing
Treatment
Supportive care and symptom control
Antiemetics
Ondansetron
4 mg IV
Repeat every 8 hours as needed
Metoclopramide
10 mg IV
Avoid in prolonged QT or extrapyramidal risk
Fluids and electrolytes
Isotonic crystalloid
Bolus 10 to 20 mL/kg for shock
Maintenance guided by urine output
Diarrhea replacement
Potassium repletion per institutional protocol
Magnesium repletion as needed
Pain control
Opioid analgesia when indicated
Titration to effect with respiratory monitoring
Avoid hypotension in shock
Hematopoietic syndrome management
Colony stimulating factors for suspected hematopoietic ARS
Filgrastim
5 mcg/kg/day SC
Start within 24 to 48 hours when feasible
Continue until ANC recovery per specialist guidance
Pegfilgrastim
6 mg SC once
Alternative when daily dosing not feasible
Sargramostim
250 mcg/m2/day SC or IV
Specialist guided use
Infection prophylaxis and treatment
Febrile neutropenia antibiotics
Cefepime
2 g IV every 8 hours
Renal adjustment per eGFR
Piperacillin tazobactam
4.5 g IV every 6 hours
Renal adjustment per eGFR
Meropenem
1 g IV every 8 hours
Reserve for resistant risk
Antiviral prophylaxis in prolonged neutropenia
Acyclovir
400 mg PO twice daily
Renal adjustment per eGFR
Antifungal prophylaxis when prolonged profound neutropenia anticipated
Fluconazole
400 mg PO daily
Consider mould active agent per local risk
Transfusion support
Platelets
Threshold < 10 x10^9/L for prophylaxis
Threshold < 20 x10^9/L with fever or bleeding risk
Higher threshold for procedures per consultant
RBC transfusion
Symptomatic anemia
Hemodynamic compromise
Stem cell transplant considerations
Not first line for most mass casualty settings
Candidate selection by specialist team
Persistent marrow aplasia with supportive failure
Exclusion of unsurvivable GI or neurovascular syndrome
Gastrointestinal and neurovascular syndrome management
GI syndrome support
Aggressive volume support
IV fluids guided by hemodynamics
Electrolyte correction
Antidiarrheals when infection excluded
Loperamide
4 mg PO once
2 mg PO after each stool
Max 16 mg/day
Nutrition support
Early enteral nutrition if tolerated
Parenteral nutrition in prolonged ileus
Neurovascular syndrome support
Critical care management
Airway protection
Vasopressors for shock
Goals of care discussions when syndrome suggests unsurvivable exposure
Specialist input for prognosis
Palliative care involvement
Internal contamination and decorporation
Potassium iodide for radioiodine exposure prophylaxis
Adult dose
130 mg PO daily
Start as soon as possible
Pediatric dosing
12 to 18 years
65 mg PO daily
3 to 12 years
65 mg PO daily
1 month to 3 years
32 mg PO daily
Birth to 1 month
16 mg PO daily
Contraindications and cautions
Iodine hypersensitivity history
Dermatitis herpetiformis
Thyroid disease monitoring in neonates
Prussian blue for cesium or thallium
Adult dose
3 g PO three times daily
Continue based on bioassay guidance
Pediatric dose
1 g PO three times daily for 2 to 12 years
Weight based specialist adjustment
Adverse effects
Constipation
Blue stools
DTPA for plutonium americium curium
Ca DTPA initial
1 g IV once as soon as possible
Prefer within first 24 hours
Zn DTPA subsequent
1 g IV daily or per specialist plan
Preferred for ongoing therapy
Monitoring
Electrolytes and trace metals
Renal function
Cutaneous radiation injury and contaminated wounds
Local radiation injury care
Early dermatology and burn consultation
Pain out of proportion
Progressive erythema and blistering
Wound management
Irrigation and debridement as indicated
Delay closure until contamination reduced when feasible
Infection prevention
Standard burn wound protocols
Early antibiotics only when infection suspected
Special Populations
Pregnancy
Maternal fetal considerations
Gestational age documentation
First trimester highest teratogenic risk
Later pregnancy growth and neurodevelopment risk
Maternal stabilization as priority
Resuscitation targets same as nonpregnant
Left uterine displacement in late pregnancy shock
Radiation counseling needs
Dose estimate coordination with radiation experts
Obstetrics and maternal fetal medicine involvement
Medication considerations
Potassium iodide use when indicated
Benefit in radioiodine exposure
Thyroid monitoring in neonate after delivery
DTPA and Prussian blue specialist guided risk benefit
Use when maternal benefit outweighs fetal risk
Lactation counseling when radionuclide present
Geriatric
Higher vulnerability factors
Reduced physiologic reserve
Dehydration risk with GI syndrome
Delirium risk
Baseline marrow compromise
Myelodysplasia prevalence considerations
Medication induced cytopenias
Treatment adjustments
Renal dosing for antimicrobials and chelators
eGFR based adjustments
Avoid nephrotoxins when possible
Delirium minimizing care
Avoid anticholinergics
Early mobilization when safe
Pediatrics
Dose and presentation differences
Higher risk per body size in similar exposure scenarios
Higher effective dose from same contamination
Faster dehydration with diarrhea
Weight based dosing for supportive meds
Fluids 10 to 20 mL/kg bolus for shock
Antiemetics per pediatric protocols
KI dosing and thyroid follow up
Neonatal thyroid suppression risk
TSH and free T4 follow up after KI exposure
Repeat testing per pediatrics
Psychosocial support needs
Family centered care
Separation minimization during decon
Background
Epidemiology
Exposure contexts
Industrial and medical source accidents
Radiography sources
Radiotherapy misadministration
Nuclear power incidents
Reactor release with contamination
Evacuation and sheltering public health measures
Deliberate radiological events
Radiological dispersal device
Improvised nuclear device
ARS rarity and risk thresholds
ARS typically requires large acute whole body dose > 0.7 Gy
Mild symptoms possible at doses around 0.3 Gy
Pathophysiology
Mechanisms
Ionizing radiation DNA damage
Double strand breaks
Mitotic cell death
High turnover tissue sensitivity
Bone marrow stem cells
GI crypt cells
Skin basal cells
Syndrome domains by dose and target organ
Hematopoietic syndrome
Marrow aplasia
Infection and bleeding
Gastrointestinal syndrome
Mucosal denudation
Bacterial translocation
Neurovascular syndrome
Capillary leak
Cardiovascular collapse
Therapeutic Considerations
Key management principles
Trauma and burn care dominates early survival in combined injury
Decontamination reduces ongoing exposure and spread
Severity estimation guides resource allocation
Growth factor rationale
Shortens duration of neutropenia
Improves hematopoietic recovery in moderate to severe exposure
Decorporation rationale
Reduces internal dose by interrupting absorption or enhancing excretion
Highest benefit when started early for specific radionuclides
Patient Discharge Instructions
Copy discharge instructions
Home care and monitoring
Shower with soap and water if advised
Avoid skin abrasion
Bag and launder clothing separately if instructed
Hydration targets
Oral fluids to maintain pale urine
Oral rehydration solution if diarrhea
Return to ED now
Fever
Temp >= 38.0 C
Chills or rigors
Bleeding
New bruising
Nosebleeds or gum bleeding
Persistent vomiting
Unable to keep fluids down
Signs of dehydration
Severe diarrhea
Blood in stool
Lightheadedness or fainting
Worsening skin injury
Increasing redness or blistering
Increasing pain
Follow up
Repeat CBC timing per clinician plan
Within 24 to 72 hours when exposure uncertain
Earlier if symptoms develop
Public health or radiation clinic follow up when arranged
Internal contamination evaluation
KI follow up thyroid testing in infants and children
References
Clinical guidance and decision support sources
Core emergency guidance
CDC Acute Radiation Syndrome clinical guidance for clinicians
ARS dose threshold > 0.7 Gy
Mild symptoms possible at 0.3 Gy
REAC TS hospital medical management guidance
ED decontamination and contamination control
Hospital operational planning for radiological incidents
HHS REMM clinical tools
Time dose effects tables for ARS
Triage and treatment resources
IAEA EPR Medical 2024 guidance
Medical triage and radiological survey principles
Contaminated wound management in emergencies
Health Canada guide on medical management of radiological exposures
Screening assessment and emergency department treatment framework
Hematopoietic support guidance
NCCN Hematopoietic Growth Factors guidance
Growth factor use in radiation induced myelosuppression
Neutropenic fever management framework
AFRRI Medical Management of Radiological Casualties handbook
Vomiting timing for dose estimation
Early CSF use for moderate to severe exposure
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.