8.2 Point-of-Care Risk Assessment & Mass Casualty/CBRNE Principles
Key Takeaways
- Mass casualty incident (MCI) triage utilizes physiological algorithms—START for adults and JumpSTART for pediatrics—to rapidly categorize casualties into Immediate (Red), Delayed (Yellow), Minor (Green), and Expectant/Deceased (Black).
- JumpSTART specifically accounts for pediatric respiratory pathophysiology, incorporating 5 rescue breaths for apneic pediatric casualties with a palpable pulse before classifying them as expectant (Black).
- The Transport Canada Emergency Response Guidebook (ERG) directs safe scene approach (uphill, upwind, upstream) and guides hazard recognition across Yellow (UN number), Blue (name), Orange (safety/guides), and Green (toxic inhalation hazards and isolation distances) sections.
- CBRNE chemical nerve agent toxicity precipitates a life-threatening cholinergic crisis (SLUDGEM/DUMBELS), managed with rapid gross decontamination, aggressive atropine titration to clear bronchial secretions, and pralidoxime chloride (2-PAM) to reverse neuromuscular paralysis.
- Blast injuries occur across five distinct physical mechanisms: primary (barotrauma/blast lung), secondary (penetrating shrapnel), tertiary (body displacement), quaternary (burns/inhalation), and quinary (toxic or chemical additives).
8.2 Point-of-Care Risk Assessment & Mass Casualty/CBRNE Principles
Disaster Medicine and Mass Casualty Incident (MCI) Triage Architecture
A Mass Casualty Incident (MCI) occurs when casualty volume or acuity overwhelms immediately available prehospital resources. Disaster medicine enforces an ethical and operational shift from individual patient optimization to a population-based utilitarian model: allocating scarce clinical assets to achieve the greatest good for the greatest number of salvageable casualties (CPCF Appendix A #10). Primary triage must be rapid, spending ≤30 seconds per adult casualty and ≤45 seconds per pediatric casualty, categorizing patients into four international tiers:
- Red (Immediate / Priority 1): Critical airway, breathing, or circulatory failure remediable by rapid, minimal field interventions. High survival probability if transported first.
- Yellow (Delayed / Priority 2): Serious systemic injuries requiring hospital surgical/medical care, whose physiological parameters remain stable for 1 to 2 hours without immediate demise.
- Green (Minor / Priority 3 / Walking Wounded): Ambulatory casualties with minor injuries capable of self-care.
- Black (Expectant / Deceased / Priority 4): Clinically dead (apneic/pulseless) or with catastrophic, non-survivable injuries where resuscitation would consume disproportionate resources.
The START Algorithm for Adult Casualties
The Simple Triage and Rapid Treatment (START) system evaluates four sequential physiological checkpoints in patients >8 years of age: Ambulation, Respirations, Perfusion, and Mental Status.
| Assessment Step | Clinical Assessment & Findings | Triage Category & Immediate Field Actions |
|---|---|---|
| 1. Ambulation | Patient is ambulatory and walks to the designated safe sector when instructed. | Green (Minor); direct to walking wounded holding sector. |
| 2. Respirations | - Apneic: Manually reposition airway.<br> - Remains apneic: Black (Deceased).<br> - Resumes breathing: Red (Immediate).<br>- Spontaneous Breathing Rate:<br> - $>30\text{ breaths/min}$: Red (Immediate).<br> - $<30\text{ breaths/min}$: Move to Perfusion. | Open airway manually. Never perform CPR during primary MCI triage. Insert a simple airway (NPA) to maintain patency if respirations resume. |
| 3. Perfusion | - Radial pulse absent OR capillary refill $>2\text{ seconds}$.<br>- Radial pulse present AND capillary refill $\le 2\text{ seconds}$. | Red (Immediate); apply commercial tourniquet or wound packing for life-threatening hemorrhage immediately.<br>Move to Mental Status. |
| 4. Mental Status | - Cannot follow simple commands ("Squeeze my hand").<br>- Follows simple commands appropriately. | Red (Immediate) (reflects cerebral hypoxia or severe shock).<br>Yellow (Delayed). |
The JumpSTART Pediatric Disaster Triage Algorithm
Pediatric cardiac arrest is overwhelmingly caused by primary respiratory failure and hypoxia. Applying adult START leads to salvageable apneic children with intact circulation being erroneously classified as deceased. JumpSTART (ages 1–8 or pediatric appearance) integrates pediatric physiology:
- Apneic with Airway Opened: Check peripheral pulse (brachial/femoral/carotid).
- If pulse is absent $\rightarrow$ Tag Black (Deceased).
- If pulse is present $\rightarrow$ Deliver 5 rescue breaths (over ~15 sec) via barrier mask/BVM. If breathing resumes, tag Red (Immediate); if apnea persists, tag Black (Deceased).
- Respiratory Rate:
- Normal pediatric range: 15 to 45 breaths/min (proceed to Perfusion).
- High risk: <15 or >45 breaths/min $\rightarrow$ Tag Red (Immediate).
- Perfusion: Presence of a palpable peripheral pulse (radial/pedal). If absent $\rightarrow$ Tag Red (Immediate).
- Mental Status (AVPU):
- Alert, Verbal, or Pain (appropriate localization/withdrawal) $\rightarrow$ Tag Yellow (Delayed).
- Pain (inappropriate posturing / decorticate / decerebrate) or Unresponsive $\rightarrow$ Tag Red (Immediate).
Transport Canada Emergency Response Guidebook (ERG) Navigation
Paramedics responding to dangerous goods transportation emergencies coordinate with CANUTEC (Transport Canada) and navigate the ERG:
- Tactical Staging: Approach and stage uphill, upwind, and upstream. Use the "Rule of Thumb" standoff distance; never enter an uncharacterized toxic vapor cloud.
- Section Navigation:
- Yellow-Bordered Pages: Numerical index by 4-digit UN/NA identification number $\rightarrow$ references 3-digit Orange Guide.
- Blue-Bordered Pages: Alphabetical index by chemical shipping name $\rightarrow$ references 3-digit Orange Guide.
- Orange-Bordered Pages (Core Guides): 62 operational guides detailing Potential Hazards (Health/Fire), Public Safety (Evacuation/PPE), and Emergency Response (Fire/Spills/First Aid).
- Green-Bordered Pages (Toxic Inhalation Hazards): If an entry in the Yellow or Blue pages is highlighted in green, the material is a Toxic Inhalation Hazard (TIH), chemical warfare agent, or water-reactive toxic gas. Responders must immediately consult Table 1 for Initial Isolation and Protective Action Distances based on Small/Large spills and Day/Night conditions.
CBRNE Threat Categories and Pathophysiology
Chemical Agents & the Cholinergic Toxidrome (SLUDGEM / DUMBELS)
Nerve agents (Sarin, Soman, Tabun, VX, Novichok) and organophosphate insecticides inhibit acetylcholinesterase (AChE), precipitating massive acetylcholine accumulation at muscarinic and nicotinic synapses:
- Muscarinic Overstimulation (SLUDGEM / DUMBELS): Salivation, Lacrimation, Urination, Defecation, GI cramping, Emesis, Miosis, and the fatal "Killer B's" (Bronchorrhea, Bronchospasm, Bradycardia). Pulmonary flooding and bronchoconstriction cause fatal asphyxiation.
- Nicotinic Overstimulation: Muscle fasciculations, cramping, and flaccid diaphragmatic paralysis.
- CNS Toxicity: Convulsions, status epilepticus, and coma.
- Antidotal Pharmacotherapy:
- Atropine Sulfate: Competitively blocks muscarinic receptors. Administer 2–6 mg IV/IM, doubling every 3–5 minutes. Titration endpoint: drying of tracheobronchial secretions and clearance of bronchospasm (clearing the lungs). Miosis and heart rate are NOT endpoints.
- Pralidoxime Chloride (2-PAM): Cleaves organophosphates from AChE before chemical "aging" occurs, reactivating the enzyme at nicotinic junctions to reverse skeletal muscle and diaphragmatic paralysis.
- DuoDote / Mark I Kits: Autoinjectors delivering 2.1 mg atropine and 600 mg pralidoxime. Midazolam is administered for seizure control.
Other CBRNE Threats & Blast Injury Mechanics
- Other Chemical Agents: Vesicants (sulfur mustard, Lewisite) cause delayed skin/corneal/airway blistering. Choking agents (chlorine, phosgene) cause non-cardiogenic pulmonary edema. Blood agents (cyanide) halt mitochondrial cytochrome c oxidase (antidote: hydroxocobalamin).
- Biological & Radiological: Category A biologicals (anthrax, plague, smallpox, botulinum) present after incubation delays. Dirty bombs (RDDs) generate localized radiological contamination; manage using Time, Distance, and Shielding.
- Blast Injury Mechanisms:
- Primary: Shockwave barotrauma to hollow organs (tympanic membrane rupture, blast lung contusion/air embolism, bowel perforation).
- Secondary: Flying shrapnel causing penetrating trauma and massive hemorrhage.
- Tertiary: Physical body displacement by blast wind resulting in blunt fractures and TBI.
- Quaternary: Thermal burns, crush injuries, and toxic smoke/CO inhalation.
- Quinary: Environmental contaminants, radiological particulate, or chemical additives.
Decontamination Operations: Gross vs Fine
Paramedics operate exclusively in the Cold Zone. Decontamination occurs in the Warm Zone:
- Gross Decontamination: Stripping all clothing immediately removes 80% to 90% of particulate contaminants. Follow with high-volume, low-pressure lukewarm water flush.
- Fine Decontamination: Systematic head-to-toe wash with warm water and soap in a contained shower corridor, with containment of runoff water before crossing into the Cold Zone.
Clinical Scenario: Chemical Release MCI
Paramedics respond to an agricultural pesticide warehouse explosion with 30 casualties:
- Staging: Crew stages 400 m upwind and uphill; ERG Yellow pages cross-reference the UN placard to Green TIH isolation distances.
- JumpSTART Triage: A 5-year-old is non-ambulatory, apneic, but has a palpable brachial pulse. The paramedic delivers 5 rescue breaths; spontaneous respirations resume at 24/min. The child is tagged Red (Immediate).
- Decontamination & Antidotes: Following rapid clothing removal and gross water flush, the child receives atropine autoinjector therapy, successfully clearing tracheobronchial secretions.
Exam Pitfalls & High-Yield Pearls
- JumpSTART Rescue Breaths: Never tag an apneic child Black without palpating a pulse and delivering 5 rescue breaths.
- Atropine Endpoint: Titrate atropine to clear bronchial secretions, not pupil dilation or tachycardia.
- ERG Highlighted Entries: Highlighted chemicals require consulting the Green pages for isolation distances.
- Blast Lung: Primary blast lung can present with delayed hypoxemia and hemoptysis 12–48 hours post-blast.
During a mass casualty incident involving a structural collapse at an elementary school, a primary care paramedic triages a 6-year-old child using the JumpSTART algorithm. The child is non-ambulatory and apneic upon initial examination. Opening the airway using a modified jaw thrust fails to stimulate spontaneous respirations. However, the paramedic palpates a distinct, regular brachial pulse. According to the JumpSTART protocol, what is the paramedic's immediate next action?
Paramedics are dispatched to a reported industrial collision involving a tanker truck displaying a Department of Transportation placard with UN identification number 1017. When consulting the Transport Canada Emergency Response Guidebook (ERG), the listing in the Yellow-bordered pages is highlighted in bright green. How must the crew navigate the ERG to establish initial scene safety?
Responding to a targeted sarin nerve agent release inside a commuter rail station, paramedics encounter a patient presenting with profound diaphoresis, rhinorrhea, pinpoint pupils, copious bubbly oral secretions, diffuse wheezing, and a heart rate of 42 beats/min. As the crew initiates pharmacological management alongside gross decontamination, which clinical parameter serves as the primary endpoint for titrating intravenous or intramuscular atropine?