It is 02:40. You arrive on the scene of a car accident. Your patient is trapped, hypotensive, and combative. You carry the drugs, the airway kit, the blood, and the scalpel. You are trained in all of it. The receiving trauma centre is 40 minutes away by road.
The question is not can you. The question is should you, here, now.
That question is answered badly more often than we admit, and it is almost never answered badly because of a knowledge gap. It is answered badly because of a situational awareness failure. The clinician knows the procedure. What they lose is the picture around it.
Situational awareness is not “being alert”
Endsley’s classic model gives us three levels, and they map onto procedural decisions almost perfectly:
- Perception — what is in front of me? Physiology, scene, team, kit, clock, transport time, weather, hazards.
- Comprehension — what does it mean? What trajectory is this patient actually on?
- Projection — what happens next? What does this patient look like in ten minutes with the procedure, and what do they look like without it?
Level 3 is where invasive procedures are decided. It is also the level that collapses first under stress, task load, and noise. Under pressure we drop back to Level 1, we see the monitor, we see the wound, we reach for the kit, and the projection never happens.
The framework below exists for one reason: to force Level 3 thinking at the moment we are least likely to do it naturally.
Three filters, applied in order
Filter 1 — Indication: does the physiology demand this before definitive care?
Note the wording. The question is not “is this procedure indicated for this condition.” It is “is it indicated in this phase of care.”
Sort your indications into two buckets:
- Time-critical — the patient deteriorates or dies before arrival without it. Tension pneumothorax. Obstructed or unprotectable airway. Catastrophic external haemorrhage. A pulseless, grossly deformed limb.
- Deferrable — the receiving team will do it faster, cleaner, and with imaging, lighting, and backup. Central access. Definitive fracture management. Most diagnostics.
Only time-critical indications survive this filter. Everything else stops here, no matter how comfortable you are performing it.
Filter 2 — Opportunity: is there a window where this displaces nothing more important?
This is the most under-used axis in prehospital decision making, and the one where good services differentiate themselves.
Transport time is the master variable. A six-minute run to a trauma centre removes the indication for nearly every on-scene procedure. A sixty-minute rural, mountain, or offshore evacuation restores it. The same patient, the same physiology, two entirely different correct answers. If your protocol doesn’t bend to transport time, your protocol is not a decision aid, it’s a habit.
Forced time is free time. Entrapment, prolonged extrication, waiting on the aircraft, these create windows that would otherwise be wasted. This is when you do the thing you would never stop for.
Default phase rule: on scene, do only what cannot be done moving. Push everything else into the transport phase.
But watch for reverse-window environments. In the back of a small aircraft, a cramped ambulance, or a winch operation, some procedures become impossible once you are moving. There, the opportunity is before departure, not en route. This inverts the default rule, and the inversion has to be recognised out loud — it is a classic source of “we’ll do it on the way” decisions that quietly become “we never did it.”
Filter 3 — Feasibility: can this be done well, here, by this team?
Estimate first-pass success in these conditions, not in the resus room where you last did it.
The honest inputs:
- Operator currency, not certification. When did you last actually do this?
- Number of trained hands available.
- Physical access to the head, chest, or limb.
- Light, noise, space, temperature, weather, contamination.
- And the one people skip: can this team manage the complication this procedure creates?
A procedure performed badly is usually worse than a procedure not performed at all. That sentence is worth putting on a wall.
The fourth filter nobody writes down
You can satisfy indication, opportunity, and feasibility and still be wrong, if failure is unrecoverable.
A failed intraosseous costs you thirty seconds and a needle. A failed RSI in a patient who was, until that moment, ventilating adequately can cost you the patient.
Weight your feasibility threshold against the downside, not the upside. High-consequence-of-failure procedures need a much higher bar than their success rates alone would suggest.
And one more thing that is always true: opportunity cost is never zero. Time spent is transport delayed, monitoring degraded, and the team leader’s attention consumed. Every procedure must buy back more time-critical physiology than it costs.
The framework applied
| Procedure | Verdict | Why |
|---|---|---|
| Finger thoracostomy | Usually yes | Immediate indication, seconds to perform, low feasibility bar |
| Tourniquet / pelvic binder | Usually yes | Fast, high yield, very hard to do badly |
| Blood or plasma | Yes, but en route | Indication is now; opportunity is the transport phase. Don’t stop for it |
| Prehospital RSI | Case by case | Indication must be strong, feasibility bar high, failure unrecoverable |
| Front of neck access (FONA) | Yes. the moment CICO is declared | All three filters resolve instantly: indication is absolute, opportunity is zero-later, feasibility is adequate anywhere. The only real failure mode is delay |
| Resuscitative thoracotomy | Narrow, but now | Tight indication and high feasibility bar — yet there is zero later opportunity |
| Central access, definitive splinting | Usually no | Fails the indication filter — deferrable to hospital |
Note how differently the same three filters weight each row. Thoracostomy passes on speed. Thoracotomy passes on the total absence of a later window. RSI is genuinely contested because the fourth filter, consequence of failure, dominates it.
FONA is the instructive outlier. It is the one row where every filter aligns and the framework has almost nothing to weigh, indication is absolute, there is no later window, and the technical bar is low enough to be met on a roadside with a scalpel and a bougie. And yet it is the procedure most often performed too late. That tells you something important: the framework’s job is not only to stop unnecessary procedures, but to remove hesitation from necessary ones. In a can’t-intubate-can’t-oxygenate situation, the decision has already been made by the physiology; the clinician’s only remaining task is to notice that, say it out loud, and cut. Services that drill the declaration — “this is a CICO, I am doing a FONA” — consistently do it faster than services that drill only the technique.
The cognitive traps, and what to do about them
The failure modes are predictable, which means they are defensible:
- Procedural momentum — “I’ve started, so I’ll finish.”
- Task fixation — the operator’s world shrinks to a 10cm square, and whole-scene awareness goes with it.
- Capability bias — “we carry it, so we should use it.” Kit generates its own indications if you let it.
- Skill-decay overconfidence — the gap between what you are credentialed to do and what you are currently good at.
Countermeasures that actually work in the field
A verbalised stop moment. Before any invasive procedure, say out loud: the indication, the window, and who is doing it. Thirty seconds. Its purpose is not permission — it is a shared mental model, and it gives the quietest person on the team a legitimate moment to say “wait.”
Pre-committed limits. Two attempts, then plan B. Decided before you start, never during. Limits set mid-procedure are not limits; they are negotiations you will lose.
A declared exit strategy before the first attempt. If this fails, we do this. Named, agreed, understood by everyone.
Time called aloud by someone not performing the procedure. “Eight minutes on scene.” Neutral, non-accusatory, relentless.
The team leader keeps their hands free during high-risk procedures. Someone must retain the global picture, and it cannot be the person with a laryngoscope in their hand.
The principle underneath all of it
On scene, you are not treating the disease You are buying the patient safe passage to somewhere the disease can be treated.
Every invasive procedure has to justify itself against that sentence. If it doesn’t buy passage, it costs it.
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