Emergency & Toxicology

Disaster medicine and public health emergency response

Clinical Overview and When to Suspect a Disaster/Public Health Emergency

— Natural: hurricanes, earthquakes, floods, wildfires, pandemics, extreme heat

— Human-caused: mass shootings, transportation crashes, industrial accidents

— CBRNE: chemical, biological, radiological, nuclear, explosive (terrorism)

— Cluster of similar symptoms in time/place (e.g., multiple ED arrivals with miosis, seizures, hypersalivation → organophosphate/nerve agent)

— Unusual disease in non-endemic area (anthrax in urban office worker, smallpox-like vesicles)

— Single severe case of a rare agent (inhalational anthrax, pneumonic plague, viral hemorrhagic fever)

— Dead animals plus sick humans (zoonotic or environmental release)

— NIMS (National Incident Management System) and ICS (Incident Command System) structure response

— Hospital Incident Command System (HICS) activates internally; Incident Commander has authority during the event

— Stafford Act authorizes federal disaster declaration; PREP Act grants liability protection for countermeasures

— CDC, ASPR, FEMA, and state health departments coordinate

Definition: A disaster is any event where casualty or resource demand exceeds available local capacity, requiring activation of surge plans, mutual aid, or federal assistance.

When to suspect a coordinated event versus isolated illness:

National framework you must know:

Phases of disaster response: mitigation → preparedness → response → recovery

Surge capacity pillars (the "4 S's"): Staff, Stuff (supplies), Space, Systems

Step 3 management: On recognizing a possible bioterror or outbreak event, the first action is to notify the local/state public health department and hospital Incident Commander, not to order confirmatory testing. Reporting triggers the cascade (CDC Laboratory Response Network, contact tracing, prophylaxis stockpiling).

Board pearl: Step 3 vignettes frame disaster medicine as a systems and ethics problem — expect questions about triage allocation, communication, mandatory reporting, and resource scarcity, not pharmacologic minutiae. Recognize the pattern of the event before treating the patient.

Presentation Patterns and Key History

— Nerve agents (sarin, VX) / organophosphates: SLUDGE/DUMBELS — Salivation, Lacrimation, Urination, Defecation, GI cramping, Emesis; plus miosis, bronchorrhea, fasciculations, seizures

— Cyanide: sudden collapse, almond breath, lactic acidosis, cherry-red skin, normal SpO₂ with venous hyperoxia

— Vesicants (mustard, lewisite): delayed (2–24 h) skin blistering, conjunctivitis, airway sloughing

— Pulmonary agents (chlorine, phosgene): upper-airway irritation immediate (chlorine) vs delayed pulmonary edema (phosgene, 4–24 h)

— Riot control (CS, OC): transient eye/airway irritation, self-limited

— Anthrax: widened mediastinum on CXR, hemorrhagic mediastinitis (inhalational); painless black eschar (cutaneous)

— Smallpox: synchronous vesicles/pustules, centrifugal distribution (face/extremities > trunk) — distinguishes from varicella

— Plague: pneumonic (rapid sepsis, hemoptysis) or bubonic (tender lymphadenopathy)

— Tularemia, botulism (descending flaccid paralysis), viral hemorrhagic fevers

— Acute Radiation Syndrome phases: prodromal (N/V, time-to-emesis predicts dose) → latent → manifest illness (hematopoietic <2 Gy, GI 6–10 Gy, CNS >10 Gy) → recovery/death

— Earlier the vomiting, worse the prognosis (<1 h ≈ lethal dose)

— Co-workers/family with similar symptoms, occupation, recent travel, suspicious packages/powders, location at time of onset, timing relative to known event

Toxidromes that scream "mass-casualty chemical event":

Biologic agents — Category A (highest priority):

Radiation exposure:

Critical history elements:

Key distinction: Smallpox vs varicella — smallpox lesions are at the same stage of development on any body region and concentrate on face/extremities; varicella lesions are at different stages ("crops") and concentrate on trunk. This is a classic Step 3 distractor in a bioterror stem.

Board pearl: Time-to-symptom-onset is your decoder ring — immediate (cyanide, nerve agents), delayed hours (phosgene, mustard), delayed days (anthrax, smallpox, radiation).

Physical Exam Findings and Field Triage Assessment

— Pinpoint miosis → cholinergic crisis (nerve agent, organophosphate)

— Mydriasis → anticholinergic, sympathomimetic, or post-anoxic

— Bronchorrhea, wheezing → nerve agent

— Stridor, upper-airway burns → chlorine, smoke inhalation, thermal injury

— Delayed crackles/pulmonary edema → phosgene

— Cherry-red → cyanide or carbon monoxide

— Cyanosis unresponsive to O₂ → methemoglobinemia (chocolate-brown blood)

— Painless black eschar → cutaneous anthrax

— Bullae with central necrosis hours after exposure → mustard

— Green (minor/walking wounded): ambulatory, follows commands

— Yellow (delayed): non-ambulatory but stable — RR <30, cap refill <2 s, obeys commands

— Red (immediate): RR >30, cap refill >2 s or absent radial pulse, doesn't follow commands — salvageable with rapid intervention

— Black (expectant/deceased): no respirations after airway repositioning

Pupillary findings:

Respiratory:

Skin:

Neurologic: fasciculations, seizures (nerve agents); descending symmetric paralysis with intact sensorium (botulism); ataxia + confusion (radiation CNS syndrome)

START Triage (Simple Triage and Rapid Treatment) — adult field triage, ≤60 sec/patient:

JumpSTART for pediatric (<8 yr or appears prepubertal): if apneic with pulse, give 5 rescue breaths before tagging black — children's apnea is more often reversible.

Hemodynamic priorities at scene: control catastrophic hemorrhage first (tourniquets, "Stop the Bleed"), then airway — the MARCH algorithm (Massive hemorrhage, Airway, Respiration, Circulation, Hypothermia/Head) supplants ABC in tactical/mass-casualty settings.

CCS pearl: In a CCS-flavored disaster stem, your first orders after recognizing mass casualty are: activate hospital incident command, lock down ED, decontaminate before entry (for chem/rad), and assign triage officer at ambulance bay. Treating the first patient before triage is a wrong answer.

Board pearl: Black tags are reassessed if resources later expand — triage is dynamic, not a one-time decision.

Diagnostic Workup — Initial Labs, Imaging, and Field Tests

— CBC, BMP, lactate, ABG/VBG, coags, type & screen, urine pregnancy

— Lactate flags occult shock, cyanide, and CO toxicity

— CO-oximetry (not standard pulse ox) for carboxyhemoglobin and methemoglobin — standard SpO₂ is falsely normal

— CXR widened mediastinum without trauma → inhalational anthrax (hemorrhagic mediastinitis)

— Bilateral pulmonary edema with normal cardiac silhouette after irritant exposure → phosgene/chlorine ARDS

— Plain films and CT for blast injury: pneumothorax, tympanic membrane rupture (sentinel of primary blast injury), bowel perforation

— Serial CBC every 4–6 h × 48 h — lymphocyte depletion kinetics (Andrews curve) estimate dose

— Absolute lymphocyte count <1000/µL at 48 h → moderate exposure; <500 → severe

— Geiger counter / dosimeter for external contamination survey before entering hospital

— Laboratory Response Network (LRN) — Sentinel (hospital), Reference (state), National (CDC) tiers

— Suspected Category A agents go to LRN reference lab; do not perform routine culture in hospital lab for suspected anthrax/plague/tularemia — risk to lab staff; notify lab director and don BSL-3 precautions

Mass casualty triage labs (per patient, minimum):

Cholinesterase activity: red-cell (true) and plasma (pseudo) cholinesterase — depressed in organophosphate/nerve agent exposure; treatment should not wait on results

Toxicology screens are rarely diagnostic for agents — clinical pattern + public health lab confirmation is the standard

Imaging:

Radiation:

Public health laboratory:

Step 3 management: A patient with sudden-onset miosis, bronchorrhea, and seizures after a subway incident — do not delay atropine/pralidoxime for confirmatory cholinesterase levels. Empiric treatment based on toxidrome is the right answer.

Board pearl: Time-to-emesis after a radiologic event is the single most useful field prognostic indicator when dosimetry is unavailable.

Diagnostic Workup — Advanced and Confirmatory Studies

— Anthrax: Gram-positive rods in chains, medusa-head colonies, non-hemolytic; PCR and immunohistochemistry confirm

— Plague (Y. pestis): bipolar "safety pin" staining on Wright/Giemsa from bubo aspirate or sputum

— Tularemia: paired serology, PCR; cultures dangerous to lab staff

— Botulism: mouse bioassay (gold standard), toxin assay from serum/stool/wound; clinical diagnosis drives antitoxin release from CDC — do not wait

— Smallpox (variola): electron microscopy, PCR at CDC only; strict isolation in negative-pressure room

— Viral hemorrhagic fevers (Ebola, Marburg, Lassa): RT-PCR; BSL-4 handling

— Cytogenetic dicentric chromosome assay — gold standard for biodosimetry

— EPR (electron paramagnetic resonance) of tooth enamel/fingernails for partial-body dose

— Bioassay (urine, fecal) for internal contamination with specific isotopes

— Whole-body counter for gamma-emitting internal contaminants

Biologic agent confirmation (LRN reference/national labs):

Chemical confirmation: GC-MS on blood/urine for nerve agent metabolites, cyanide level (>3 mg/L toxic), carboxyhemoglobin (>25% severe), methemoglobin (>30% severe)

Radiation dose reconstruction:

Blast injury workup: TM exam (if intact, primary blast injury unlikely but not excluded), eFAST, CT chest/abdomen, troponin if blast lung suspected

Pandemic surveillance: syndromic surveillance (BioSense, ESSENCE), wastewater testing, sentinel ILI networks — detect outbreaks before case clustering is obvious

Key distinction: Anthrax vs influenza — both cause flu-like prodrome, but inhalational anthrax progresses to widened mediastinum, hemorrhagic pleural effusions, and shock within 1–3 days, and rarely causes rhinorrhea. A patient with severe "flu" plus widened mediastinum is anthrax until proven otherwise.

Board pearl: The hospital's role in bioterror confirmation is collect, package, and ship per LRN protocols — definitive confirmation occurs at state/CDC labs. Performing in-house culture risks aerosolization and staff exposure.

Risk Stratification and Incident Command Management Logic

— Triggers: notification of mass-casualty incident, ≥X simultaneous critical patients (institution-defined), suspected CBRNE, regional/state emergency declaration

— Incident Commander has ultimate authority during event (often the on-duty administrator or ED chief), supported by Operations, Planning, Logistics, Finance/Admin, Safety, Liaison, Public Information sections

— Conventional: usual space/staff/supplies stretched

— Contingency: adapted (e.g., PACU as ICU)

— Crisis standards of care: fundamental shifts — utilitarian allocation, altered consent norms, formally declared by state authority

— Validated scoring (SOFA most common), short-term survival prioritization, exclusion of categorical criteria based solely on age/disability/socioeconomic status (illegal and unethical)

— Reassess at fixed intervals (typically 48 and 120 h); withdrawal of life support to reallocate is ethically permissible if protocolized and applied uniformly

— Chemical: remove clothing (removes ~80–90% of contaminant), copious water/soap, before entering ED

— Radiologic: external survey, decon to <2× background; lifesaving care precedes decontamination if patient unstable

— Biologic: standard/contact/droplet/airborne precautions per agent; smallpox and VHF require airborne + contact + dedicated negative-pressure room

Hospital Incident Command activation:

Surge tiers:

Triage allocation under crisis standards (e.g., ventilator shortage):

Decontamination decisions:

PPE level selection (OSHA): Level A (vapor-tight suit, SCBA) for unknown vapor; Level C (air-purifying respirator) for known agent with adequate O₂; hospital decon usually Level C

CCS pearl: In a CCS case with incoming mass casualties, early orders: activate HICS, cancel elective OR cases, mobilize blood bank, set up cohort areas, call disaster medical assistance team (DMAT), and notify public health — all within the first simulated hour.

Board pearl: Crisis standards of care must be declared by state authority, not invented bedside — the individual physician does not unilaterally ration.

Pharmacotherapy — First-Line Antidotes and Countermeasures

— Atropine 2–6 mg IV q5min, doubled until bronchial secretions dry (pupils are NOT the endpoint — secretions are); pediatric 0.05 mg/kg

— Pralidoxime (2-PAM) 1–2 g IV over 15–30 min, then infusion 500 mg/h — reactivates acetylcholinesterase before aging

— Benzodiazepines (midazolam 10 mg IM via DuoDote/autoinjector, or diazepam) for seizures

— DuoDote autoinjector: atropine 2.1 mg + pralidoxime 600 mg — field use

— Hydroxocobalamin 5 g IV over 15 min (preferred, especially in smoke inhalation — no methemoglobinemia risk)

— Alternative kit: amyl nitrite → sodium nitrite → sodium thiosulfate (avoid nitrites in concurrent CO poisoning)

— Anthrax (inhalational): ciprofloxacin or doxycycline + 1–2 additional agents (linezolid/meropenem) × 60 days; anthrax immune globulin or raxibacumab for systemic disease; post-exposure prophylaxis = cipro/doxy × 60 days plus vaccine

— Plague: streptomycin or gentamicin; alternative doxycycline/cipro

— Tularemia: streptomycin or gentamicin

— Botulism: equine heptavalent antitoxin from CDC — neutralizes circulating toxin only, will not reverse existing paralysis; supportive ventilation

— Smallpox: tecovirimat (TPOXX); vaccinia immune globulin for complications; ring vaccination within 4 days of exposure

— Potassium iodide (KI) for radioactive iodine exposure — most protective if given before or within hours of exposure; greatest benefit <40 y, pregnant, children

— Prussian blue for cesium/thallium

— DTPA for plutonium, americium, curium

— Filgrastim/sargramostim for hematopoietic syndrome (ANC nadir)

Nerve agents / organophosphates:

Cyanide:

Carbon monoxide: 100% NRB; hyperbaric O₂ if COHb >25%, LOC, neuro deficits, pregnancy with COHb >15%, or ischemia

Methemoglobinemia: methylene blue 1–2 mg/kg IV; avoid in G6PD deficiency (use ascorbic acid or exchange transfusion)

Biologic agents:

Radiation:

Step 3 management: Atropine titration endpoint in organophosphate poisoning is drying of bronchial secretions and resolution of bronchospasm — not tachycardia, not pupil size. This is a frequently tested distractor.

Procedures, Decontamination Protocols, and Mass Vaccination Logistics

— Located outside ED entrance (warm zone); hot zone = scene

— Two-lane (ambulatory/non-ambulatory), gender-separated when feasible

— Disrobe → bag/tag clothing (evidence + further contamination control) → soap and warm low-pressure water × 3–5 min → survey → don clean gown

— Wastewater containment ideal but not required if delay would harm patient (EPA emergency exemption)

— Stockpiled ventilators (Strategic National Stockpile)

— Bridge strategies: shared ventilators ("vent splitting") only as last resort and ethically contested — generally NOT recommended outside extremis

— BiPAP/HFNC for non-ICU surge spaces if airborne precautions feasible

— Strategic National Stockpile delivers within 12 h of federal request

— Local health department operates PODs for community antibiotic/vaccine distribution

— Throughput goal often >1000 persons/hour

— Smallpox: ring vaccination around index case (contacts + contacts-of-contacts); mass vaccination only if outbreak uncontained

— Pandemic influenza/novel pathogens: tiered prioritization (healthcare workers, high-risk, then general public) — guided by ACIP and state plans

— Isolation = sick persons separated; Quarantine = exposed but asymptomatic persons restricted

— Authority: state public health > federal CDC (interstate/international)

Decontamination station setup:

PPE donning/doffing: doffing is the highest-risk step for self-contamination — buddy check, ABHR between layers, dedicated doffing observer (Ebola-era lesson)

Airway and ventilation in surge:

Blood product management: activate massive transfusion protocol; whole blood for trauma; coordinate regional blood bank; consider walking blood bank in austere settings

Mass prophylaxis / Points of Dispensing (PODs):

Mass vaccination strategy:

Quarantine vs isolation:

CCS pearl: Order droplet + airborne + contact precautions and negative-pressure room for suspected smallpox, VHF, or pneumonic plague before any further workup — late isolation is a frequent wrong-answer trap.

Special Populations — Elderly, Renal, and Hepatic Impairment

— Disproportionate mortality (Katrina, heat waves, COVID): impaired mobility, dependence on electricity (oxygen, dialysis), polypharmacy, dementia/delirium with displacement

— Functional needs registries help locate at-risk individuals pre-event; nursing homes require evacuation plans (CMS Emergency Preparedness Rule)

— Heat wave mortality concentrated in elderly on diuretics, anticholinergics, beta-blockers (impaired thermoregulation)

— Atropine, pralidoxime: same initial dose regardless of age — under-dosing in cholinergic crisis is far more dangerous than overdose

— Cipro/levofloxacin (anthrax PEP): renal-adjust in CrCl <50; doxycycline preferred in significant CKD (no renal adjustment)

— Aminoglycosides (plague, tularemia): renal-dose, monitor levels; consider doxycycline alternative

— Tecovirimat: hepatically metabolized, no renal adjustment needed

— Identify pre-event, coordinate with regional ESRD Network

— Emergency potassium-restricted diet, kayexalate/patiromer, hyperkalemia protocols

— Peritoneal dialysis as backup; emergency hemodialysis prioritization

— Avoid acetaminophen-heavy analgesia stockpiles in hepatic patients

— Adjust benzodiazepine choice: lorazepam, oxazepam, temazepam (no active metabolites) preferred over diazepam in cirrhosis

— Disaster pharmacies/Emergency Prescription Assistance Program (EPAP) provide 30-day refills of chronic medications to displaced uninsured persons

— Cross-reference home medications early — interruption of warfarin, insulin, antiepileptics, immunosuppressants drives preventable readmissions

Elderly in disasters:

Antidote dosing adjustments:

Dialysis patients in disasters:

Hepatic impairment:

Medication continuity:

Step 3 management: A displaced 78-year-old with dementia and CHF arriving at a shelter without medications — first step is medication reconciliation and 30-day refill via EPAP/disaster pharmacy, not new diagnostic workup. Continuity prevents the next disaster within the disaster.

Board pearl: The "second wave" of disaster mortality is chronic-disease decompensation among elderly — dialysis, oxygen, insulin, dementia care.

Special Populations — Pregnancy, Pediatrics, and Vulnerable Groups

— Radiation: cumulative fetal dose <50 mGy generally safe; >100 mGy increases malformation/IQ loss risk (highest 8–15 weeks); KI strongly recommended for pregnant exposed to radioiodine — protects maternal and fetal thyroid (single dose to avoid neonatal hypothyroidism)

— Anthrax PEP: ciprofloxacin is first-line in pregnancy (benefits > theoretical risk); doxycycline acceptable short-course alternative

— Smallpox vaccine: contraindicated in pregnancy except in confirmed exposure (risk > benefit reversed)

— Iodide thyroid blockade: yes; if repeated dosing needed, monitor neonate for hypothyroidism

— Higher minute ventilation → greater inhaled toxin dose

— Larger surface-area-to-mass → faster dermal absorption and hypothermia

— Thinner skin, lower to the ground (heavier-than-air gases like chlorine, sarin concentrate at floor level)

— Smaller blood volume → rapid hemorrhagic shock

— Limited verbal report → triage must rely on physiology (JumpSTART)

— Psychological vulnerability and dependence on caregivers — never separate from caregiver unless decontamination requires

— Atropine 0.05 mg/kg IV, 2-PAM 25–50 mg/kg

— Pediatric DuoDote / atropine autoinjectors (AtroPen 0.25/0.5/1 mg) by weight

— Hydroxocobalamin 70 mg/kg

— Doxycycline acceptable for anthrax PEP in children — short courses outweigh dental staining risk in life-threatening exposure

— Use unique identifiers, photographs; National Center for Missing & Exploited Children operates disaster reunification systems

— Document any unaccompanied minor immediately; mandatory reporting if abandonment suspected

Pregnancy:

Pediatrics — vulnerabilities:

Pediatric antidote dosing:

Reunification:

Other vulnerable groups: disabled, non-English speakers (use certified interpreters, not family), incarcerated, undocumented (treat without immigration inquiry — EMTALA and public health override)

Key distinction: In radiation emergencies, KI protects only against radioactive iodine (thyroid) — it does not protect against cesium, plutonium, or external gamma exposure. Misapplication is a classic distractor.

Complications and Adverse Outcomes

— Blast injuries: tympanic rupture, blast lung (pulmonary contusion, pneumothorax, air embolism), hollow viscus perforation, traumatic amputation, crush syndrome, secondary infection

— Crush syndrome: rhabdomyolysis → hyperkalemia, hypocalcemia, AKI, compartment syndrome; aggressive IV fluids before extrication if possible

— Chemical: ARDS (chlorine, phosgene, mustard), chemical pneumonitis, corneal burns, secondary bacterial pneumonia

— Radiation: pancytopenia → infection, hemorrhage; GI mucositis → sepsis from gut translocation; cutaneous radiation injury (delayed, weeks)

— Biological: sepsis, DIC, ARDS, meningitis (anthrax 50% mortality even with treatment)

— Cancer risk from radiation (latency 5–40 y); thyroid, leukemia, breast, lung

— Post-traumatic stress disorder, depression, substance use — both survivors and responders

— Chronic respiratory disease in first responders (WTC cohort: asthma, COPD, sarcoid-like granulomatous disease, cancers — WTC Health Program)

— Survivor's guilt, complicated bereavement

— Secondary contamination of ED staff (inadequate PPE) — sentinel events in sarin and Ebola responses

— Nosocomial transmission (SARS, MERS, COVID, Ebola — amplified in hospitals)

— Medication errors during surge; protocol drift; documentation lapses

— Workforce burnout, moral injury, attrition

— Outbreak of preventable disease in shelters (measles, norovirus, influenza, TB reactivation)

— Vector-borne post-flood (West Nile, dengue, leptospirosis)

— Contaminated water — cholera, hepatitis A, Vibrio vulnificus wound infections

Acute complications by mechanism:

Late complications:

Healthcare-system complications:

Public health complications:

CCS pearl: Crush syndrome from prolonged entrapment — start isotonic saline at 1–1.5 L/h before extrication, monitor for hyperkalemia (sodium bicarbonate, calcium, insulin/glucose); do not delay fluids for IV access in field — IO is acceptable.

Board pearl: Responder health is a public-health issue — registries (WTC, post-deployment) track latent disease and qualify workers for federal compensation programs.

When to Escalate — ICU, Specialty Consult, and Regional Resources

— Same usual indications (hemodynamic instability, respiratory failure, neuro decline) plus triage scoring under crisis standards

— Specific to agents: any inhalational anthrax, pneumonic plague, severe nerve-agent exposure with seizures, blast lung with hypoxemia, ARS with neutropenia

— Poison Control (1-800-222-1222) — first call for any toxic exposure, 24/7, free; activates regional toxicologist

— CDC Emergency Operations Center (770-488-7100) — bioterror, novel pathogen, antitoxin/antiviral release, smallpox/anthrax/botulism suspicion

— REAC/TS (Radiation Emergency Assistance Center, 865-576-1005) — 24/7 radiation medical consultation

— CHEMM, REMM, WISER — federal online decision-support tools

— Infectious disease, trauma surgery, burns, ophthalmology (vesicant exposure), psychiatry early

— Transfer to trauma center, burn center, regional treatment center for special pathogens (e.g., Emory, Nebraska, NIH for VHF/Ebola)

— Mutual aid via state EMS compact and Emergency Management Assistance Compact (EMAC) for inter-state resource sharing

— Federal: Disaster Medical Assistance Teams (DMAT), Disaster Mortuary Operational Response Teams (DMORT), National Disaster Medical System (NDMS) reception hospitals

ICU admission criteria in disaster context:

Consult triggers:

Regional escalation:

Pediatric-specific transfer: to designated pediatric receiving hospitals; co-locate with caregivers when possible

Crisis-standards triage committee: institutional triage officer/committee — never the treating clinician alone — makes allocation decisions, providing moral and legal protection and consistency

Step 3 management: Suspected inhalational anthrax — within the first hour, you should have: empiric multidrug antibiotics started, ID and Public Health notified, CDC EOC called for raxibacumab/anthrax immune globulin release, hospital infection control activated (standard precautions only — anthrax is not person-to-person), and patient admitted to ICU.

Board pearl: "Who do you call first?" stems in disaster medicine usually want Poison Control or Public Health/CDC, not a specialist consult — system-level reporting drives the broader response.

Key Differentials — Within Disaster/Toxic Exposure Category

— Miosis + secretions + fasciculations → nerve agent / organophosphate (not cyanide, not CO)

— Sudden collapse + lactic acidosis + normal SpO₂ → cyanide

— Cherry-red skin + headache + N/V after fire/heater → carbon monoxide

— Chocolate-brown blood, cyanosis unresponsive to O₂ → methemoglobinemia (dapsone, benzocaine, nitrates, aniline dyes)

— Immediate eye/airway irritation, green-yellow gas → chlorine

— Delayed (4–24 h) pulmonary edema after exposure → phosgene

— Delayed (2–24 h) bullae, conjunctivitis → mustard (vesicant)

— Flu-like prodrome → mediastinal widening + hemorrhagic shock → inhalational anthrax

— Flu-like → rapidly progressive pneumonia + hemoptysis + person-to-person spread → pneumonic plague

— Painful regional lymphadenopathy (bubo) + fever → bubonic plague

— Painless eschar with edema → cutaneous anthrax

— Painful ulcer + regional adenopathy (ulceroglandular) → tularemia

— Descending flaccid paralysis, cranial nerves first, clear sensorium → botulism

— Synchronous vesicopustules, face/extremity predominance → smallpox

— Prodromal N/V <1 Gy: mild, likely survivable

— 1–4 Gy hematopoietic: lymphopenia by 48 h, neutropenia/thrombocytopenia weeks 2–4

— 6–10 Gy GI: bloody diarrhea, mucosal sloughing, sepsis; high mortality without HSCT

— >10 Gy CNS/cardiovascular: ataxia, hypotension, death within days — uniformly fatal

Distinguishing chemical agents by toxidrome:

Distinguishing biologic agents:

Distinguishing radiation syndromes by dose:

Key distinction: Botulism vs Guillain-Barré vs myasthenia gravis — botulism is descending, symmetric, with fixed dilated pupils and intact sensorium, no sensory deficits; GBS is ascending with sensory involvement and elevated CSF protein; MG fluctuates and improves with edrophonium/pyridostigmine. Single botulism case in a vignette + foodborne or wound source + bioterror context → call CDC for antitoxin.

Key Differentials — Non-Disaster Mimics

— Heat stroke: hot, dry or sweaty, altered mental status, environmental exposure

— Anticholinergic: hot, dry, mydriasis, urinary retention, "mad as a hatter"

— Sympathomimetic: diaphoretic, mydriasis, hypertension, tachycardia

— Serotonin syndrome: hyperreflexia, clonus (especially lower extremity), serotonergic drug

— NMS: lead-pipe rigidity, antipsychotic exposure, days–weeks onset

Sepsis vs anthrax/plague/tularemia: Routine community-acquired pneumonia/sepsis is far more common. Red flags suggesting bioterror or zoonosis: rapidly progressive illness in previously healthy young adult, multiple simultaneous cases, occupational exposure (postal worker, lab worker, hunter, rancher), characteristic imaging (mediastinal widening), bloody pleural effusion.

Influenza vs inhalational anthrax: Both present with fever, myalgia, malaise. Anthrax features rarely seen in flu: widened mediastinum, hemorrhagic pleural effusion, profound dyspnea with shock, absence of significant rhinorrhea/sore throat.

Food poisoning vs botulism: Staph aureus and norovirus produce vomiting/diarrhea; botulism produces descending paralysis with minimal GI symptoms after onset of neurologic disease. Home-canned foods, honey in infants, IV drug use (wound botulism) raise suspicion.

Chickenpox vs smallpox: Varicella — pruritic, lesions in different stages, trunk-predominant, mild systemic illness. Smallpox — synchronous stage, face/extremity-predominant, severe prodrome with high fever before rash.

Heat stroke vs anticholinergic toxicity vs sympathomimetic vs serotonin syndrome vs NMS:

MI vs cyanide/CO during fire/industrial exposure: Both cause chest pain, dyspnea; check COHb and lactate before attributing to ACS alone.

PTSD vs acute stress disorder vs adjustment disorder post-disaster: ASD <1 month, PTSD ≥1 month with intrusion/avoidance/negative cognition/arousal; adjustment disorder lacks full criteria but causes functional impairment.

Key distinction: Single cases of unusual presentations in non-endemic regions, or clusters of similar presentations, should always raise bioterror or outbreak suspicion before settling on a benign differential. Maintain a low threshold to report.

Secondary Prevention, Discharge Planning, and Long-Term Countermeasures

— Anthrax (inhalational exposure): ciprofloxacin 500 mg BID or doxycycline 100 mg BID × 60 days + 3-dose anthrax vaccine series

— Plague (close contact pneumonic): doxycycline or cipro × 7 days

— Smallpox: vaccinia vaccination within 4 days of exposure ± tecovirimat

— Botulism: observation, equine antitoxin if symptomatic; no chemoprophylaxis effective

— Tularemia: doxycycline or cipro × 14 days for high-risk exposure

— Radioactive iodine: KI single dose, repeat per state radiation authority

— Anthrax vaccine adsorbed (AVA) — military, lab workers, select responders

— Smallpox (ACAM2000, JYNNEOS) — lab personnel, select military/responders

— Hepatitis A, typhoid, polio — for international disaster responders per CDC

— Confirm chronic disease medications resumed; bridge supplies

— Anticoagulation, insulin, antiepileptics, immunosuppressants — verify continuity

— Pain management with opioid stewardship despite mass-casualty context

— WTC Health Program, post-deployment health registries, radiation exposure registries (NIOSH)

— Enables long-term surveillance, compensation eligibility, research participation

— Thyroid US periodically if radioiodine exposure, especially pediatric

— Hematologic surveillance for leukemia

— Lifelong skin examination for cutaneous radiation injury site

Post-exposure prophylaxis (PEP) summary:

Pre-exposure vaccination (occupational):

Discharge medication reconciliation in disaster context:

Mental health follow-up: Routine PTSD/depression screening at 1, 3, 6, 12 months post-event for survivors and responders; warm handoff to mental health within 2 weeks for high-risk

Registry enrollment:

Cancer surveillance after radiation:

Step 3 management: A postal worker exposed to anthrax-contaminated mail — prescribe ciprofloxacin × 60 days plus anthrax vaccine series (3 doses), monitor for GI/tendon side effects, document occupational exposure, and report to OSHA/employer health.

Board pearl: 60-day antibiotic course for anthrax PEP reflects spore latency — shorter courses risk reactivation.

Follow-Up, Monitoring Parameters, and Rehabilitation

— Initial post-event clinic visit within 1–2 weeks (medication reconciliation, wound check, screening)

— 1, 3, 6, 12 months: physical, mental health, social work

— Annually thereafter for high-exposure cohorts

— Radiation: CBC weekly × 6 weeks then monthly × 3 (hematopoietic recovery); TSH and thyroid US annually for radioiodine; cancer surveillance per dose

— Chemical (vesicant): pulmonary function testing, ophthalmology follow-up, dermatologic care for chronic wounds

— Nerve agent: cholinesterase activity returns over weeks (RBC) to days (plasma); neurocognitive sequelae screening

— Anthrax survivors: pulmonary rehabilitation, mental health, completion of 60-day antibiotic course

— Blast TBI: serial neurocognitive testing, vestibular therapy, audiology

— Trauma-focused CBT and prolonged exposure therapy are first-line for PTSD

— SSRIs (sertraline, paroxetine FDA-approved for PTSD), prazosin for nightmares

— Group therapy and peer support, especially among responders

— Screen at every visit for first year — symptoms often emerge late

— Pulmonary function, mental health, cancer screening per registry protocol

— OSHA-mandated medical surveillance for hazmat workers

— Recognize delayed symptoms (radiation skin injury, PTSD, anthrax PEP completion)

— Avoid future occupational exposures; smoking cessation (synergistic with inhalation injury)

— Vaccinations updated (tetanus after wounds, influenza, COVID-19, pneumococcal as indicated)

Survivor follow-up cadence:

Specific monitoring parameters:

Pulmonary rehabilitation: structured 6–12 week programs for chemical inhalation survivors, dust-exposure (WTC cohort), blast lung

Wound and burn care: outpatient dressing changes, pressure garments, scar management, reconstructive surgery referral

Mental health:

Responder health surveillance:

Patient counseling topics:

CCS pearl: Schedule a 2-week post-disaster follow-up appointment before discharge, with explicit handoff to primary care and mental health — unscheduled follow-up is the most common pathway to lost-to-care in displaced populations.

Ethical, Legal, and Patient Safety Considerations

— Utilitarian framework (greatest good for greatest number) supersedes individual-patient maximization only when formally declared by state authority

— Allocation must use objective, validated criteria (SOFA, short-term survival); cannot use age, disability, race, insurance, or social worth

— Triage officer/committee, not treating physician, makes allocation decisions — protects therapeutic alliance and reduces moral injury

— Withdrawal of life-sustaining treatment for reallocation requires institutional protocol, transparent criteria, and family communication; ethically permissible when protocolized

— Implied consent for life-saving treatment of incapacitated patient — applies in mass-casualty events

— Federal EUA (Emergency Use Authorization) countermeasures (e.g., monoclonal antibodies, novel antivirals) require fact-sheet disclosure of investigational status when feasible — not full informed consent

— PREP Act provides liability immunity for covered countermeasure administration during declared emergency

— Suspected bioterrorism — immediate report to local/state public health → CDC; reporting is mandatory and not subject to patient consent

— Reportable diseases per state list (anthrax, plague, smallpox, botulism, VHF, novel influenza universally reportable)

— Mandatory child/elder abuse reporting persists during disasters

— Public health authority can mandate; subject must have right to legal review

— Least-restrictive means principle: voluntary > mandated; home > facility

— Step 3 high-yield safety issue: When patients are evacuated across facilities/states, medication lists, code status, allergies, and follow-up plans are commonly lost — formal handoff documents and EHR interoperability (or paper "go-bags") reduce preventable harm

Crisis standards of care ethics:

Informed consent in emergencies:

Mandatory reporting:

Quarantine/isolation due process:

EMTALA: suspended only by HHS Section 1135 waiver during declared emergency, allowing redirection of patients to alternative care sites

Documentation in surge: legal records still required; use disaster forms, unique identifiers, photos for unidentified patients

Transition-of-care risk:

Duty to respond vs personal safety: Physicians have an ethical (not always legal) duty to respond; institutions must provide PPE, training, and family support — responder refusal due to inadequate PPE is ethically defensible

Board pearl: When a Step 3 vignette pits individual-patient advocacy against system-level rationing, the correct answer almost always involves invoking the institutional triage protocol rather than personally allocating or withholding.

High-Yield Associations and Rapid-Fire Clinical Facts

First call for bioterror suspicion: local/state public health department + hospital incident command → CDC EOC (770-488-7100)

First call for chemical exposure: Poison Control 1-800-222-1222 → regional toxicologist

First call for radiation event: REAC/TS 865-576-1005

DuoDote autoinjector: atropine 2.1 mg + 2-PAM 600 mg

Atropine endpoint: drying of bronchial secretions (NOT pupil size or heart rate)

Hydroxocobalamin preferred cyanide antidote in smoke inhalation (no methemoglobinemia risk vs nitrites)

Cherry-red skin: cyanide or CO

Chocolate-brown blood: methemoglobinemia → methylene blue (avoid in G6PD)

Widened mediastinum + flu-like illness: inhalational anthrax

"Safety pin" bacilli on Wright stain: Yersinia pestis (plague)

Medusa-head colonies, GPR in chains: Bacillus anthracis

Descending flaccid paralysis, clear sensorium: botulism — call CDC for equine antitoxin

Synchronous rash, centrifugal: smallpox; asynchronous "crops," centripetal: varicella

KI protects only against radioactive iodine (thyroid); give as soon as possible, greatest benefit in <40 y, pregnant, children

Pediatric triage: JumpSTART; give 5 rescue breaths to apneic child with pulse before tagging

MARCH algorithm (tactical/mass casualty): Massive hemorrhage → Airway → Respiration → Circulation → Hypothermia

START categories: Green (walking), Yellow (delayed), Red (immediate), Black (expectant/dead)

Crush syndrome fluids: isotonic saline 1–1.5 L/h, ideally before extrication

Anthrax PEP: cipro or doxy × 60 days + 3-dose vaccine series

NIMS/ICS/HICS = incident command framework; PREP Act = liability immunity; Stafford Act = federal disaster declaration

Laboratory Response Network (LRN): Sentinel → Reference → National (CDC) for confirmation of select agents

Crisis standards of care must be declared by state authority, not individual hospitals or clinicians

EMTALA can be waived only by HHS Section 1135

First decontamination step: remove clothing (~80–90% contaminant reduction) before water/soap rinse

Board pearl: The most tested disaster medicine concept on Step 3 is system-level decision-making — who to call, when to isolate, how to triage, and what protocol governs allocation. Master the framework, not the rare diagnoses alone.

Board Question Stem Patterns

Stem 1 — Subway nerve agent: "Dozens of passengers arrive with miosis, salivation, fasciculations, and seizures after an incident on a subway." → Activate HICS, decontaminate before ED entry, empiric atropine titrated to dry secretions + pralidoxime + benzodiazepine; notify Poison Control and public health.

Stem 2 — Anthrax letter: "Postal worker with 2-day flu-like illness, now hypotensive; CXR shows widened mediastinum." → Suspect inhalational anthrax. Cipro + linezolid + meropenem empirically, ID and public health consult, ICU admission, anthrax immune globulin/raxibacumab from CDC. PEP for co-workers: cipro × 60 days + vaccine.

Stem 3 — Suspicious rash: "Multiple cases of vesicular rash; lesions synchronous, face and extremities > trunk." → Smallpox. Negative-pressure airborne + contact isolation, notify public health immediately, ring vaccination of contacts, tecovirimat for cases.

Stem 4 — Botulism cluster: "Several diners at a church potluck develop diplopia, dysphagia, descending weakness; sensorium clear." → Foodborne botulism (or bioterror via food). Call CDC for equine heptavalent antitoxin, supportive ventilation, public health investigation of food source.

Stem 5 — Mass shooting triage: "Twenty patients arriving simultaneously; which patient first?" → Apply START: red tag (RR >30 or absent radial pulse or non-following commands but breathing) before yellow/green/black. Tourniquets and MARCH for hemorrhage.

Stem 6 — Crisis standards ventilator allocation: "Three patients, one ventilator." → Invoke institutional triage protocol/committee using validated scoring (SOFA); do not unilaterally allocate as treating physician.

Stem 7 — Radiation accident: "Worker at nuclear plant with vomiting 30 min after exposure." → Early vomiting = high dose; serial CBC for lymphocyte kinetics, call REAC/TS, decontaminate externally, KI if radioiodine, supportive care, biodosimetry.

Stem 8 — Shelter outbreak: "Diarrhea outbreak in evacuation shelter." → Norovirus most likely; cohort symptomatic, hand hygiene, environmental cleaning with bleach, notify public health.

Stem 9 — Pediatric chemical exposure: "Toddler at industrial accident with secretions." → JumpSTART, weight-based atropine and pediatric DuoDote, keep with caregiver during decon when feasible.

Stem 10 — Ethics: "Family demands ICU admission for non-survivable injury during mass casualty." → Compassionate communication, palliative care, expectant (black) triage per protocol — resources reserved for salvageable patients under declared crisis standards.

Board pearl: Step 3 disaster stems reward you for recognizing the pattern, calling the right system resource, and following the protocol — not for memorizing antidote pharmacokinetics.

One-Line Recap

Core teaching point: Disaster medicine on Step 3 is fundamentally a systems-and-safety discipline — recognize the pattern (toxidrome, cluster, exposure history), activate the right framework (HICS, public health, Poison Control, REAC/TS, CDC EOC), triage by protocol (START/JumpSTART/MARCH and validated crisis-standards scoring), decontaminate before bringing contamination into the hospital, and treat empirically with the correct antidote or countermeasure while reporting and coordinating across the system.

Recognition: Cluster, unusual disease in non-endemic area, characteristic toxidrome (miosis + secretions = nerve agent; widened mediastinum + flu = anthrax; descending paralysis + clear sensorium = botulism; synchronous centrifugal rash = smallpox) — pattern-match before confirming.

Action: Decontaminate → empiric antidote → notify public health and incident command → confirm via Laboratory Response Network. Atropine to dry secretions, hydroxocobalamin for cyanide, KI only for radioiodine, cipro/doxy × 60 days + vaccine for anthrax PEP, equine antitoxin from CDC for botulism, tecovirimat plus ring vaccination for smallpox.

System: NIMS/ICS/HICS structure the response; crisis standards of care require state declaration and protocolized triage by a committee, not the bedside clinician; PREP Act provides liability immunity for covered countermeasures; EMTALA can be waived only by HHS Section 1135; mandatory reporting is non-negotiable.

Safety and ethics: Protect responders with appropriate PPE and decontamination; maintain medication continuity for displaced patients (especially elderly, dialysis, insulin-dependent); screen survivors and responders for PTSD/depression at 1, 3, 6, 12 months; enroll in long-term registries for radiation, chemical, and dust exposures.

Board pearl: When a Step 3 stem feels overwhelming, ask three questions — What is the pattern? Who do I call? What protocol applies? — and the right answer almost always emerges.