01Principles and purposeThe professional or clinical skill and the decisions it supports.
Major-incident medicine requires a clinician to think about both one patient and the whole response. A prolonged intervention for the first person encountered may leave other immediately treatable casualties unseen, while a purely administrative label achieves little if no lifesaving care follows. Triage links a brief assessment to an action and a destination, then repeats as physiology, resources and hazards change.
The first reports are inevitably incomplete. State what is known, what is estimated and what is still uncertain. M/ETHANE provides a common structure: major-incident status, exact location, type of incident, hazards, access, number and severity of casualties, and emergency services present or required. An early concise report can mobilise resources while the on-scene team obtains better information.
Key points
- A major incident requires special response arrangements; it is not defined by one fixed casualty number.
- Send an early M/ETHANE message and update it as facts change rather than waiting for a complete assessment.
- The NHS Ten Second Triage tool is intended for all first responders and uses observable findings without requiring measured vital signs.
- The NHS Major Incident Triage Tool adds physiological assessment for trained clinical responders and applies across adult and paediatric casualties.
- A triage category is a time-stamped priority for treatment and movement, not a diagnosis or a permanent label.
- Control severe bleeding and open an airway when indicated while maintaining the wider casualty assessment and transfer plan.
02Situations and prioritiesThe context, relevant information and actions that matter most.
Consider the consequences for casualties, responders and services, including hazardous exposure or infrastructure failure. A modest number of critically injured people may exceed local capacity even when a larger group with minor injuries would not.
Look for severe external bleeding, inability to walk, impaired response and abnormal or absent breathing. These findings guide rapid initial actions without requiring a complete injury inventory or definitive diagnosis.
Fire, unstable structures, traffic, violence and contamination can change while treatment is underway. Work with incident command and specialist responders; entering an unsafe area without the necessary protection creates additional casualties.
Children, people with communication difficulties and those separated from carers may be hard to assess quickly. Use the tool as trained, record limitations and ensure reassessment rather than equating difficulty communicating with a fixed neurological deficit.
03Assessment and interpretationHow to gather information, assess the situation and recognise uncertainty.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
M/ETHANE situation report - Why
- Create shared understanding and mobilise the response.
- Interpretation and limitations
- Separate confirmed facts from estimates. Give usable location and access information, current hazards, an approximate casualty distribution and resources required; revise the report when those assumptions change.
- 02
Ten Second Triage assessment - Why
- Provide rapid initial prioritisation by any trained first responder.
- Interpretation and limitations
- Walking casualties enter P3; non-walkers are assessed for severe bleeding, talking, penetrating injury and breathing. The current NHS tool labels a non-breathing casualty as not breathing and considers CPR if resources allow.
- 03
NHS MITT assessment - Why
- Refine priority using a consistent clinical algorithm.
- Interpretation and limitations
- After its earlier steps, a non-walking casualty who responds to voice and is over two years becomes P1 if respiratory rate is outside 12–23/min or pulse is at least 100/min; otherwise the pathway reaches P2.
- 04
Repeated casualty assessment and tracking - Why
- Detect deterioration and maintain continuity during movement.
- Interpretation and limitations
- Record identity where known, category, time and lifesaving interventions. Re-triage at appropriate transition points and after clinical change; a previously walking casualty can later require urgent treatment.
04Worked approachesCases with ordered reasoning, an action and a check of the outcome.
01Worked caseRefining priority after a rail collisionA clinical responder assesses a non-walking adult with no catastrophic bleeding. The person breathes, responds to voice, has respiratory rate 24/min and pulse 96/min. Initial responder triage was P2.+
- 1Confirm the scene sector is safe and that the casualty is in the clinical responder’s care. Check for immediately correctable airway obstruction or bleeding while repeating the assessment.
- 2Apply MITT in order: there is no catastrophic bleeding, the person cannot walk, is breathing, responds to voice and is older than two years.
- 3Compare the measured respiratory rate with the MITT range of 12–23/min. At 24/min the casualty is P1; the later pulse of 96/min does not cancel an earlier P1 decision.
- 4Update the visible category and record the time and findings. Communicate the change to the treatment and evacuation lead so that it results in a revised priority, not just a changed label.
- 5Verify that the casualty reaches the designated priority-care area and is reassessed. Continue appropriate treatment while organising evacuation; do not assume that categorisation itself resolves the underlying injury.
02Initial-response branchUsing Ten Second Triage before full clinical assessmentFirst responders reach several casualties before the full clinical response is established.+
- 1Direct walking casualties to the designated safe area as P3, with supervision and later reassessment. Among non-walkers, identify severe bleeding, control it with appropriate pressure, tourniquet or packing and assign P1.
- 2For a talking non-walker without severe bleeding, check for a penetrating injury to the front or back: its presence leads to P1, while its absence leads to P2 under TST.
- 3For a non-talking casualty, open the airway if able and assess breathing. A breathing casualty is P1 and may need recovery positioning; if not breathing, consider CPR when resources allow and report the finding accurately.
03Coordination branchKeeping the receiving system informedThe first casualty count changes as further areas become accessible and transport resources arrive.+
- 1Send an updated M/ETHANE report with the revised number and severity of casualties, new hazards and safe access routes. Distinguish the incident’s overall picture from one patient handover.
- 2Work through the designated command and evacuation arrangements to distribute patients to appropriate receiving services, preserving identification and treatment records during movement.
- 3Reassess priorities when resources or physiology change, and hand over outstanding safety concerns, unsearched areas and separated children or vulnerable adults before leaving a role.
05Feedback, follow-up and evidenceReview outcomes, seek feedback and identify what to improve.
- Repeat triage after deterioration, important intervention or transfer between scene, treatment and evacuation areas; include the time and findings supporting any category change.
- Maintain a tally of casualty priorities and destinations so that individuals are not lost between responders, vehicles and receiving facilities.
- Review responder safety and resources throughout the incident, escalating new hazards or inadequate support through the agreed command structure.
- After the acute response, preserve records, support affected people and staff, and contribute factual observations to the organised debrief and learning process.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
TST and MITT are distinct tools
Do not merge branches into a new improvised algorithm. For example, TST begins with walking whereas MITT checks catastrophic bleeding first; each should be applied in its specified sequence.
The youngest children require particular care
MITT assigns P1 at the age step for a non-walking, breathing child who responds to voice but is not over two years old. This protects priority despite apparently reassuring vital signs.
Non-breathing categories need exact language
Current TST uses not breathing with CPR considered if resources allow. MITT has its own airway and dead-category branch, including a conditional rescue-breath provision for children under twelve after submersion or smoke inhalation.
A P3 label needs supervision
Walking identifies an initial lower priority, not absence of injury. Provide a safe place, clear instructions and a route for reassessment, especially after blast, smoke exposure or evolving symptoms.
07Common pitfallsFrequent interpretation and management errors.
- 01
Do not delay the first incident report until every casualty has been counted or the full mechanism is confirmed.
- 02
Do not use ordinary individual-patient assessment habits to improvise a hybrid triage tool with different thresholds and branch order.
- 03
Do not allow a category change to remain only on a chart; it must reach the people organising treatment and evacuation.
- 04
Do not use age, disability, appearance or perceived social value as an informal substitute for the approved clinical triage process.