Lesson Overview
So far this course has assumed one casualty and one first-aider. But a blast, a crash, a collapsed building, or a flood can produce more casualties than there are trained hands. The careful sequence you learned for a single casualty then gives way to a harder judgement: how to do the most good with too little.
A first-aider is a trained first responder, not a medic. Triage by a first-aider does not replace a medical-led response; it begins one and supports it. Where this lesson touches decisions that are properly clinical, such as how fast is too fast a rate of breathing, or whether a casualty is beyond saving, it marks them as medical decisions, made on the ground under the direction of medical staff and confirmed by the College. You sort so the right help reaches the right casualty first. You do not diagnose, and you do not decide alone who lives. The duty of care from Lesson 01 still holds: care is owed to everyone by the measure of their need alone, and triage is how you meet that duty when need outruns capacity, never how you escape it.
This is the knowledge layer; the drills behind it are taught and certified in person, under qualified supervision, with the clinical detail confirmed by the College's medical staff. You do only what you are trained and authorised to do. By the end you will be able to explain why triage is needed, name the four categories, work the sorting sequence as a sieve, state the principle that guides it, describe how a first-aider supports a medical-led mass-casualty scene, and describe the scope of buddy aid and a clear handover.
Key Terms
- Mass-casualty situation: any incident where the casualties exceed the people and equipment available. It need not be large; two badly injured people and one first-aider can qualify.
- Triage: sorting casualties into priority groups by the urgency of their need, so limited help reaches those who benefit most. From the French trier, to sort.
- Sift and sort: the two steps of triage; sifting separates those who can walk from those who cannot, and sorting assigns each remaining casualty a priority.
- Triage sieve: a fixed sequence of yes-or-no checks (can they walk, are they breathing, how fast is the breathing and circulation) that drops each casualty into a category quickly and the same way every time.
- Primary triage: the first, fast sort done on every casualty as you find them, using the sieve. Secondary triage is a slower, fuller re-sort done later, usually by medical staff, once the worst is in hand.
- Priority categories (T1 to T4): immediate (T1), urgent (T2), delayed (T3), and expectant (T4); the dead are recorded separately.
- Expectant: a casualty so badly injured that they cannot be saved with the people and equipment present. They are kept comfortable and not abandoned; scarce effort goes to those who can be saved.
- Buddy aid: the immediate care a first-aider gives before a medic or clinician arrives. It has a defined scope.
- Casualty Collection Point (CCP): a chosen, safer spot to which casualties are gathered so that help, kit, and the handover can be concentrated in one place.
Why triage is necessary, and the principle behind it
With one casualty, the choice is simple: you treat that casualty. With six and you alone, every minute on one is a minute denied to the other five, and someone out of sight may bleed to death while you work. Good intentions applied in arrival order can cost lives. Triage imposes order on a scene with more need than capacity. It accepts that you cannot do everything for everyone, and obeys one sentence: do the most good for the most people. Use the hands and kit present to benefit the greatest number of casualties who have the best chance of survival.
This reverses an instinct. Normally the most badly injured person gets your fullest attention; in a mass-casualty situation, a casualty too gravely hurt to be saved with the resources to hand may have to wait, so that two or three who can be saved are not lost. You treat by need and survivability, not by how loud, how visible, or how near a casualty is. The loudest casualty is often not the most urgent: a person who can scream has, by that fact, an open airway and the breath to drive it, while the quiet casualty a few steps away may be slipping from a blocked airway or a bleed you have not yet seen. Triage trains you to be pulled by need, which is sometimes silent, not by noise, which is sometimes the lesser problem.
What triage never does is change who is owed care. Comrade, civilian, and former enemy are sorted by the same clinical rule and nothing else, as Lesson 01 set out. To ration care by rank, familiarity, nationality, or anything other than clinical need would not be triage but misconduct. And the hardest decisions are still made humanely: a casualty who must wait is still spoken to, still covered, still told help is coming; a casualty who cannot be saved is still kept warm and not left alone. Sorting by need is not coldness. It is the only honest way to give the most people the best chance.
The four priority categories
The Army uses four categories, T1 to T4, with the dead recorded separately. They are a shared language for medic, civilian paramedic, and first-aider alike, which is why a clear category at handover saves time later. Each carries a colour and a plain meaning, and it is the plain meaning, not the number, that you act on.
- T1, Immediate (red). Life-threatening but savable now. Injuries treatable with simple, fast measures that kill quickly if untreated, such as catastrophic limb bleeding or a blocked airway. These are the casualties a first-aider can most often turn from dying to living, and they are treated first.
- T2, Urgent (yellow). Serious but can wait a short while. Not immediately life-threatening; some delay is acceptable. The casualty needs proper care soon, but has minutes to spare without losing their chance.
- T3, Delayed (green). The walking wounded. Injuries needing attention that can safely wait longer. A casualty who walks to you has, by walking, shown a working airway, breathing, and circulation, which is why walking earns the lowest priority.
- T4, Expectant (blue). So badly injured that they cannot be saved with the people and equipment present. This is the hardest category. The expectant casualty is not abandoned: they receive comfort, warmth, a hand to hold, pain relief within scope, and a human presence, so that no one dies alone. But scarce hands are not held on them while savable casualties wait, because to spend an hour failing to save one is to let two who could have lived die untended. The category is honest about the limits of the help present, not about the worth of the person.
The decision to call a casualty expectant is among the gravest in all of casualty care, and it is a medical decision, not a first-aider's. A first-aider may find a casualty plainly beyond simple help, with no breathing after the airway is opened, and place them low in priority so effort goes to the savable; that much is part of the sieve. But the firm label of expectant, and any decision to withhold continued effort, belongs to the medical staff leading the scene, on their direction, confirmed by the College in training. Where you are unsure, you treat, you flag the casualty for the medic, and you let the clinical call be made by the person qualified to make it.
The dead are confirmed, recorded, and treated with dignity; resources are not diverted from the living to them, but the dead are not stepped over as obstacles either. Confirming death, like declaring a casualty expectant, is a clinical judgement; a first-aider records what they find, reports it, and does not lightly write a casualty off. A category is only a snapshot, so triage is repeated and never done once: treat what you find rather than upgrading a casualty on a guess about how they might worsen, and re-sort as the picture changes.
A simple, usable method: the triage sieve
Under stress you cannot weigh a casualty against a textbook. What you can do is run the same short set of questions on every casualty, in the same order, and let the answers drop each one into a category. That is the triage sieve: a sieve because casualties fall through it quickly and are caught at the level their answers set. It is fast on purpose, a matter of seconds per casualty, because its job is to sort the whole group, not to treat any one person. The sieve has three questions.
First question: can the casualty walk? Having taken charge and made the scene as safe as it allows, call out clearly: "If you can hear me and you can walk, come to me." Everyone who gets up and walks over has, in that single act, shown a working airway, breathing strong enough to fuel movement, a circulation good enough to stand, and a brain awake enough to obey. They are T3, Delayed, the lowest priority, and several can now help you. Sending the walking wounded to one spot sorts the easiest cases in seconds and clears them out of the way, so the scene shrinks to those who could not move and therefore need you most.
Second question: is the casualty breathing? Go to each casualty who did not walk, in turn. Look, listen, and feel for breathing for a few seconds. If the casualty is not breathing, open the airway with a simple manoeuvre (the head-tilt and chin-lift or jaw thrust from Lesson 04) and look again. If they start to breathe once the airway is open, that is a life saved by a single action, and they are T1, Immediate: leave them positioned to keep the airway open and move on. If they still do not breathe after the airway is opened, then with the people and equipment present at this stage they are beyond simple saving; in a mass-casualty sieve they are placed in the lowest-effort category (T4, Expectant) so hands go to the savable, and they are flagged for the medical staff, whose decision the expectant label finally is. This is the hardest single step in the sieve, and it is exactly the step that is clinical: you are not declaring death and you are not declaring the casualty unsavable for good, you are sorting under scarcity and handing the grave call to those qualified to make it.
Third question: what is the breathing rate, and the circulation? For a casualty who is breathing, the speed of their breathing and the state of their circulation tell you how hard their body is fighting. Breathing that is very slow or very fast is a danger sign; so is a failing circulation, shown by skin that is pale, cold, and clammy, and by a pulse that is weak or absent at the wrist. A casualty who is breathing but breathing too fast or too slow, or whose circulation is plainly failing, is T1, Immediate. A casualty breathing at a steady rate with a good circulation, but who did not walk because of their injuries, is T2, Urgent. The exact numbers that count as "too fast" or "too slow", and how the circulation check is taught and judged, are set by the College's medical staff and confirmed in person: do not invent thresholds from this page. The principle holds even without the numbers: the casualty working hardest to breathe, or whose circulation is failing, goes to the front of the queue.
Those three questions, walk, breathe, then rate-and-circulation, are the whole of primary triage at this level. Run them the same way on every casualty and you will sort a chaotic scene into an order you can act on, without a chart and without freezing.
The discipline of the sieve: do the quick killers and move on
The hardest part of the sieve is not the questions but the discipline of stopping. At every casualty you will be tempted to settle in and treat. You must not, yet. During primary triage you give only the two quickest life-saving actions a single pass allows, then move on:
- Open an airway that is closed, and position the casualty (on their side, in the recovery position) so it stays open. This takes seconds and can turn a dying casualty into a breathing one.
- Stop a catastrophic external bleed, the kind that will empty a casualty in minutes, with hard direct pressure, a packed wound, or a tourniquet where you are trained to use one (Lesson 03). This too takes little time and saves a life that would otherwise be lost before you returned.
Those two actions, and only those, are done during the sieve. You do not splint, dress minor wounds, give comfort care, or settle to monitor a casualty during the first pass. The arithmetic is unforgiving: stop to treat one casualty fully and the sieve never finishes, and a casualty you have not yet reached, perhaps the most savable of all, dies undiscovered while you work on someone already past help or already stable. The first pass belongs to the whole group, not to any one person in it. Assign each casualty a category, mark it so others can see it (a card, a tag, a piece of tape, a written letter, whatever is to hand and is the practised method), and go to the next. Only when every casualty has been sieved and marked do you turn back to give full care, starting with the T1 casualties, in the careful MARCH and ABCDE sequence you already know.
Marking matters as much as sorting. A category held only in your head is lost the moment a second helper arrives or you are called away. A casualty visibly marked T1 is one the next pair of hands, perhaps the arriving medic, can act on without re-sorting from nothing. So the rule is: sort, do the quick killers, mark, and move, every time.
The sieve, in one picture
MANY CASUALTIES
Make the scene safe. Call for help. Begin.
|
v
+-------------------------+
| Can the casualty WALK? |
+-------------------------+
| |
YES NO
| |
v v
+-----------+ +-----------------------+
| T3 | | Is the casualty |
| DELAYED | | BREATHING? |
| (and can | +-----------------------+
| help you)| | |
+-----------+ NO YES
| |
v |
Open the airway. |
Breathing now? |
| | |
YES NO |
| | |
v v v
+------+ +-----------+ +-------------------------+
| T1 | | T4 | | Breathing RATE too fast |
|IMMED.| | EXPECTANT | | or too slow, OR |
+------+ | (comfort; | | CIRCULATION failing? |
| medical | | (medic sets thresholds) |
| decision)| +-------------------------+
+-----------+ | |
YES NO
| |
v v
+------+ +--------+
| T1 | | T2 |
|IMMED.| | URGENT |
+------+ +--------+
During this sieve do ONLY two things: open the airway and position;
stop catastrophic bleeding. Mark each casualty. Then move on.
Re-sift and re-sort whenever anything changes. Treat fully afterwards,
starting with T1.
A simple sequence to carry it: shout, sweep, treat
You are not expected to carry a chart in your head under stress, only three actions in order: shout, sweep, and treat the quick killers. This is the sieve worn as a habit, named for what you actually do.
Shout. Having taken charge, made the scene as safe as it allows, and called for help, call out clearly: "If you can hear me and you can walk, come to me." All who get up and walk over are T3, and can help you. This is the first question of the sieve. It shrinks an overwhelming scene and shows you who cannot move and therefore needs you most.
Sweep. Go to each casualty who did not walk, in turn, spending only the few seconds the sieve allows on each. You are sorting, not treating. Run the remaining questions, breathing, then rate-and-circulation, in the MARCH and ABCDE order you already know: catastrophic bleeding, then airway, then breathing and circulation. Do only the two actions a single sweep allows: open an unconscious casualty's airway and place them on their side, and stop catastrophic external bleeding with pressure, a dressing, or a tourniquet where trained. Assign a category, mark it, and move on. Resist the pull to treat fully; if you stop, the sweep never finishes and casualties you have not reached go unfound.
Treat the quick killers. Once every casualty is swept and categorised, go back and give full care, starting with T1: the careful MARCH sequence, reassessment, warmth, comfort. Set your walking wounded to help. Re-sort whenever something changes, because a category is a snapshot: a T2 whose breathing worsens becomes a T1, and a T1 you have treated may settle. Keep passing back the count, categories, and what you need.
Supporting a medical-led response
A first-aider sorting casualties is the first move in a response that becomes medical-led as soon as trained medical help arrives. Your task is to start the response well and then support it, not to run the scene once those qualified to lead it are present. Two things make you genuinely useful to the medic, paramedic, or doctor who takes charge.
The first is that you have already imposed order. Because you shouted, sieved, and marked, the arriving medical staff inherit a scene that is sorted rather than chaotic: the walking wounded are gathered in one place, the casualties who could not move are each marked with a category, the catastrophic bleeds are stopped and timed, and you can tell them in one breath how many casualties there are and how they break down. That lets a medic begin treating and re-sorting at once instead of spending precious minutes discovering what you already know. The single most valuable sentence you can offer is a clear count and breakdown: how many in all, and how many T1, T2, T3, and T4.
The second is that you then do as you are directed. The medical staff carry out the slower, fuller secondary triage, revise your categories where their training tells them to, and make the clinical calls that are theirs and not yours: the rate that is dangerous, the casualty who is expectant, the order of evacuation. You support. You continue the within-scope care you are trained to give, hold pressure, keep airways open, keep casualties warm, help move them to the casualty collection point, write down times, and free the medic's hands for what only they can do. The discipline that mattered during the sieve, doing what is yours and handing on what is not, matters just as much once help arrives. A first-aider who keeps doing simple things well under direction is worth far more than one who reaches beyond their training and has to be undone.
The limits of buddy aid, and handing over
A first-aider's value comes from staying inside a defined scope. Within buddy aid are the things this course teaches: controlling catastrophic bleeding by pressure, packing, and the tourniquet you are trained to use; opening an airway and using the recovery position; sealing a chest wound with your issued seal; preventing and managing shock; keeping a casualty warm; moving and carrying; sorting casualties with the sieve; and giving a clear handover. Done promptly, these most often decide whether a casualty lives, and they are precisely what a mass-casualty scene needs many hands doing well.
Beyond buddy aid are procedures belonging to a medic, nurse, or doctor, which a first-aider does not attempt: needle decompression of a chest; a surgical airway; drips or fluids into a vein or bone; controlled drugs, including most strong painkillers; definitive splinting of complicated fractures; the cleaning, closing, or stitching of wounds; and the clinical decisions this lesson has flagged throughout: declaring a casualty expectant, confirming death, and setting the rate or sign that makes a casualty immediate. The line is not bureaucratic. An untrained attempt can kill a casualty who would otherwise live, is unsupported by the medical and legal chain, and steals time from what you can do. The honest answer to "should I try?" is almost always no: keep doing what is within scope, keep the casualty alive, and get the person who can do more.
Buddy aid is the first link in a chain. Hand over early rather than late, through your team leader. Because the Principality works closely with the civilian system, the receiver is often a civilian paramedic who may not know military shorthand, so pass the casualty over briefly and plainly, as practised: who they are, what happened, the injuries you found, what you did and when (the time of any tourniquet above all), the category you assigned, and what they need next. Give times, answer directly, and do not guess at a casualty's chances aloud, least of all within their hearing. Once a medic or the civilian service takes the casualty, clinical charge passes to them; you assist, protect, and document. In a mass-casualty scene the handover is not one event but many, casualty by casualty, in priority order, and the categories you marked are what let it go quickly and in the right sequence.
The weight of it, and looking after yourself
It would be dishonest to teach triage as a tidy drill and stop. The method is simple; living with it is not. To walk past a wounded person during the sweep without stopping, to give only comfort to a casualty you have had to place as expectant, and to choose, under pressure, who waits, is among the heaviest things a person can be asked to do. You may carry it afterwards as guilt, as the question of whether you sorted rightly, or as the deeper ache of having seen suffering you could not relieve. None of this means you sorted wrongly or that something is broken in you. It is the normal response of a decent person to a terrible situation, and the very weight of it is part of what keeps triage humane rather than callous.
Understanding why triage is an act of care, and not its opposite, is what lets you carry that weight without being crushed by it. You did not abandon the casualty you placed as expectant; you gave them comfort and a presence, and you spent the saving effort where it could actually save. You did not ignore the casualty you walked past in the sweep; you were finding the others so that none died undiscovered. Rehearsed beforehand, calmly and often, the sieve becomes something your hands can do while your heart catches up. That is why mass-casualty drills are practised until the method is automatic: so that on the day, the thinking is already done and you are free to be humane.
Afterwards, the weight is dealt with, not buried. The carer's own mind and body are the subject of Lesson 09, which treats moral injury, normal reactions, and the support that is a strength rather than a weakness. The essential point belongs here too: buddy aid has limits not only in what your hands may do but in what one person can carry, and looking after yourself after a hard scene is part of the duty of care, owed to you as much as by you. Hand the heaviest of it on, just as you hand on the clinical decisions, to those whose place it is to help.
In Practice: A Crash on a Rural Road
A vehicle leaves a rural road in poor weather: four casualties, one walking and dazed, one screaming and clutching an arm, one bleeding heavily from the thigh, and one silent and still. You are first on scene, alone for a few minutes. You make the scene safe, send word for help with a count of four, and shout for anyone who can walk; the dazed casualty comes, now a T3 (Delayed) who can hold a dressing. You sweep the other three with the sieve. The screaming casualty is breathing steadily, with a good circulation and a serious but survivable arm: breathing and circulation are sound, so despite the noise this is T2, Urgent, and the dressing of the arm waits. The thigh is a catastrophic bleed that will empty the casualty in minutes, so this is T1, Immediate: you apply a tourniquet now and note the time. The silent casualty is not breathing; you open the airway and look again, and still no breath comes, so with the resources present this casualty is sorted to the lowest-effort category, T4, Expectant. You cover them, do not leave them alone in spirit, and flag them for the medical staff, whose decision the expectant label finally is, rather than make that grave call yourself. You mark each casualty so the order is visible. Then you treat the T1 fully, direct your walking casualty to help, and re-sort as the ambulance nears. When the civilian paramedic arrives you give a clear count and breakdown first, then hand each casualty over by priority with times and findings, including the tourniquet time, and from then you work under their direction. You did not treat the loudest, the nearest, or the most distressing first; you treated in the order that saved the most lives, kept every casualty within the decency owed to them, and stayed inside what you are trained to do.
Check Your Understanding
- Why can treating casualties in the order you reach them cost more lives than sorting them first? Use the principle of "the most good for the most people" in your answer, and explain why care is still owed to every casualty equally.
- Work the triage sieve aloud as three questions, and say what category each answer leads to. Why does a casualty who can walk earn the lowest priority, and why is the screaming casualty often not the most urgent? Which step of the sieve is properly a medical decision, and how should a first-aider handle it?
- Give three actions that fall within buddy aid and three that fall outside it, including the clinical decisions a first-aider does not make, and explain why the line is drawn where it is. How does a sorted, marked scene help the medical staff who take over?
Reflection (write a short paragraph): Triage asks you to walk past a wounded person during the sweep without stopping, and sometimes to give only comfort to a casualty you cannot save. Why is this, properly understood, an act of care rather than its opposite? What would you need to have rehearsed beforehand to do it calmly and humanely, and what does that tell you about how mass-casualty drills should be trained? Where would you turn afterwards to deal with the weight of it (see Lesson 09)?
Summary
- A mass-casualty situation is any incident where casualties outnumber the carers and kit present; it need not be large. Treating in arrival order wastes the minutes that decide who lives.
- Triage sorts casualties by urgency so limited help reaches those who can most benefit. The governing principle is to do the most good for the most people, and it never changes that care is owed to everyone by need alone, sorted humanely.
- The four categories are T1 immediate (life-threatening but savable now), T2 urgent (serious, can wait a short while), T3 delayed (walking wounded, can wait), and T4 expectant (beyond saving with the resources present, kept comfortable, never abandoned); the dead are recorded separately and treated with dignity. A category is a snapshot and is revisited.
- The usable method is the triage sieve, three questions on every casualty: can they walk (if so, T3), are they breathing after the airway is opened, and what is the breathing rate and circulation. Run it as shout, sweep, then treat the quick killers fully, starting with T1, doing only airway-and-position and stopping catastrophic bleeding during the sweep, and marking every casualty.
- A first-aider is a first responder, not a medic: declaring a casualty expectant, confirming death, and setting the dangerous rate are medical decisions, made under medical direction and confirmed by the College. The first-aider sorts, supports a medical-led response, and does the simple things well under direction.
- Triage rations care by survivability, never by who a person is; comrade, civilian, and former enemy are sorted by the same rule. Buddy aid has firm limits: do what you are trained and authorised to do, never attempt medic-level procedures, hand over early and clearly with times and categories, and look after yourself afterwards, for the weight of triage is real and the carer's mind is the subject of Lesson 09.
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