Mass Casualties and Triage in Military and Civilian Environment

Priority

Colour

Label

Immediate

Red

P1 or T1

Urgent

Yellow

P2 or T2

Delayed

Green

P3 or T3

Expectant

Blue/black

Dead

Black/white

P or Priority System

This has historically been used within UK major incident planning where casualty number associated with Irish Republican Army (IRA) bombings has been small, resulting in what an experienced London-based surgeon has described as a ‘sweaty morning’ in the emergency room. In these situations, the relatively small numbers of the injured were managed within existing resources with little impact on the day-to-day working of the affected hospitals. Three patient groups were defined:

P1: Immediate – cannot wait – patients needing immediate resuscitation/surgery
P2: Urgent – can tolerate short delay >30 min
P3: Delayed – can tolerate long or indefinite delay

Plainly, this system works well with small numbers being cared for in a major European general hospital but will not cope with overwhelming numbers. In these situations, the T or treatment system was suggested. Four or five categories are defined:

T1: Immediate – but not patients with such severe injury that good outcome is unlikely or where care would overburden resources in terms of time and material
T2: As P2 above
T3: As P3 above
T4: Expectant group which includes patients with severe, multisystem injury where prognosis is poor and care is unduly time-consuming and demands scarce resources

It is interesting to observe that one of the drivers for change from conventional triage to mass casualty triage has been the recent threats of international terrorist attacks. There is now a growing trend to move towards the T system but also incorporating a coloured label and a description as outlined in Table 23.1. This recognises the need to conform to one system in all events and makes training easier, particularly across national boundaries. Sensibly, there remains a degree of flexibility. In the United Kingdom, for example, while the T system is agreed where casualty numbers are small (in the 10 s) after a transport accident, the T4 or expectant category is not invoked. However, when managing hundreds of patients, the T4/expectant category may be invoked, at least for a time.

In summary, a sensible suggestion for future use is summarised below:

T1 – Red label – Immediate: These cannot wait. Treatment needed as soon a possible.
T2 – Yellow label – Urgent: Casualties with serious injury. Treatment needed after a limited delay.
T3 – Green label – Delayed: Indefinite delay, while not desirable can be tolerated.
T4 – Blue or Black label – Expectant: Likely not to survive but optimism maintained and will be treated if and when conditions improve.
T5 – Black or White label – Dead: Should not enter the clinical arena but may do so.

Take-Home Point

When faced with overwhelming casualties, the P or priority system will fail, resulting in unnecessary morbidity and mortality.

Take-Home Point

Civilian triage systems maintain an optimistic outlook in the face of mass casualties. In our modern cities, it is hard to visualise a total overwhelming abundance of resources.

23.4 Methodology

We have suggested a system to sort casualties in the event of mass casualties. The next question is how to apply the system. Historically, triage was performed by the most senior doctor present – usually a senior surgeon – and decisions were based on observed anatomical injury. This is now recognised to be a poor method and results in both overtriage and undertriage. In brief, this approach is flawed for a number of reasons:

Anatomical triage requires a fully exposed patient which is rarely possible in the chaos of a mass casualty incident.
Considerable experience is required and will rarely be available.
Even in experienced hands, full anatomical examination will fail to detect significant bleeding in the chest and abdomen in over 40 % of cases.

This realisation has resulted in a move towards a more discriminating approach – namely, measurement of physiological parameters. A two-part physiological system has evolved, referred to as a sieve-sort methodology.

23.5 The Sieve-Sort Approach to Mass Casualties

This is a two-part approach when applying mass casualty triage to injured patients.

Triage Sieve

The first part – the sieve is an algorithm and is illustrated in Fig. 23.1. This figure is from the author’s hospital major incident policy. While the word ‘priority’ is used to describe the patient categories, the method uses the mass casualty T system and an expectant group is included.

Fig. 23.1

Major incident triage sieve flow diagram

The sieve is a physiologically based method using the ABC approach advocated by the Advanced Trauma Life Support (ATLS) programme of the American College of Surgeons. It is ideally suited to prehospital sorting by trained but not necessarily medically qualified first responders but is also used by emergency room medical teams working at a hospital entrance selecting patients for admission to resuscitation room bays in receiving hospitals. Figure 23.2 shows triage sieve in operation during a major incident exercise at a London hospital.

Fig. 23.2

A London hospital triage training exercise in 2006. Note the field triage label using both red colour code and ‘immediate’ description

Triage Sort

This component is a hospital (resuscitation room)-based method requiring a more time-consuming and accurate assessment. Its aim is to iron out undertriage or overtriage. It is typically performed by a trained triage officer and needs skill and equipment to perform accurately. The method uses the physiological findings outlined in Table 23.2 and yields a score or coded value for each of the three physiological measurables. The sum of the three scores gives the triage revised trauma score (T-RTS). Table 23.3 shows the relationship between the T-RTS and triage priority.

Table 23.2

Triage sort based on revised trauma score

Score	Respiratory rate	Systolic BP	Glasgow coma score
0	0	0	3
1	1–5	1–49	4–5
2	6–9	50–74	6–8
3	>29	75–90	9–12
4	10–29	>90	13–15

Table 23.3

Scores converted to triage priorities

Triage revised trauma score	Triage group or priority
4–10	T1
11	T2
12	T3
1–3 (hospital only)	T4
0	Dead

Source for all tables used: Ministry of Defence [13] publication – with permission

This is not a one-off method. It may be repeated over time and allows a refining of priorities following therapeutic interventions. Figure 23.3 shows a summary of triage sort included in a major London hospital’s major incident policy. Note the comment that a decision to invoke mass casualties is a high-level political decision by medical and management senior staff working in concert. Note too that it utilises the newly agreed T treatment approach.

Fig. 23.3

Major incident triage sort flow diagram

23.6 Effect-Related Triage

In an attempt to add a scientific basis to the application triage and of therapy, following triage Lennquist has described effect-related triage. This approach to triage is based on which effect a decision or therapy will have for a given injury in a given situation. For example, in considering a 40 % burn, if an intravenous fluid therapy is instituted as early as possible, the average mortality is between 5 and 10 %. If therapy is delayed for up to 24 h because of a poor triage decision, then the average mortality is >90 %. Effect-related triage forces triage raters to consider available resources and to set priorities in an effect-related way. Lennquist clearly shows that failure to do so results in increased mortality. This approach lends itself to wider application and has relevance for facial injuries with threatened airway, life-threatening thoracic injuries, intra-abdominal injuries and major injuries to the musculoskeletal system. Application of effect-related triage requires knowledge and training. It is particularly suited to hospital triage where a more scientifically based approach is mandated.

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