4.1 Trauma Overview

4.1 Trauma Assessment and Shock

Trauma is roughly 6-10% of the NREMT Paramedic blueprint, but shock recognition cuts across nearly every trauma item. The paramedic's job in the first minutes is to find and stop life-threatening hemorrhage and to recognize shock — inadequate tissue perfusion and oxygen delivery — before the blood pressure collapses. Hemorrhage is the leading cause of preventable trauma death, so assessment runs the MARCH sequence (Massive hemorrhage, Airway, Respiration, Circulation, Head/Hypothermia) rather than the classic ABCs: catastrophic external bleeding is controlled first.

A core decision tool is the ATLS classification of hemorrhagic shock, which links blood loss (in a healthy ~70 kg adult) to expected vital-sign changes. The exam tests the pattern, especially that blood pressure is preserved until Class III.

Classes of hemorrhagic shock

The key trap: in Class I-II, systolic BP is normal because compensatory vasoconstriction and tachycardia maintain it. Narrowing pulse pressure (rising diastolic from vasoconstriction) and tachycardia are the earliest signs. By Class III the patient is decompensating — falling BP, confusion, weak/absent radial pulse. A young, fit patient or one on beta-blockers can mask tachycardia and crash suddenly, so do not be reassured by a 'normal' pressure.

MAP, perfusion, and permissive hypotension

Perfusion depends on mean arterial pressure (MAP), estimated as diastolic + 1/3(systolic - diastolic). A MAP of roughly 65 mmHg is the usual minimum for organ perfusion, but in uncontrolled hemorrhage the goal is not a normal pressure. Permissive (controlled) hypotension deliberately keeps the pressure low enough to perfuse the brain and heart yet low enough that a forming clot is not blown apart by aggressive fluids.

The practical target in penetrating torso trauma without head injury is a palpable radial pulse (≈ systolic 80-90 mmHg) or maintenance of mentation. Crystalloid is titrated in small 250 mL boluses, not opened wide.

The critical exception: in traumatic brain injury (TBI), permissive hypotension is contraindicated. A single episode of hypotension worsens TBI outcomes, so those patients need a higher systolic target (≥110 mmHg, see 4.2). Aggressive crystalloid also dilutes clotting factors and drops temperature, feeding coagulopathy — another reason blood products are preferred when carried.

Hemorrhage control and the lethal triad

Control external bleeding in a stepwise fashion:

1. Direct pressure — firm, focused manual pressure is first-line for almost all external bleeding.
2. Tourniquet — for life-threatening extremity hemorrhage not controlled by pressure. Place 2-3 inches proximal to the wound (or 'high and tight' if rapid), tighten until bleeding stops and the distal pulse is gone, and note the time of application. Pain is expected; a tourniquet that does not eliminate the distal pulse only worsens venous bleeding.
3. Wound packing + pressure dressing — for junctional wounds (groin, axilla, neck) where a tourniquet cannot be placed; pack hemostatic or plain gauze tightly to the bleeding vessel and hold pressure ~3 minutes.

TXA (tranexamic acid) is an antifibrinolytic that stabilizes clot; the prehospital dose is 1 g IV/IO over ~10 minutes, ideally within 3 hours of injury — give it for hemorrhagic shock or suspected major hemorrhage. Where whole blood or components are carried, resuscitate in a balanced 1:1:1 ratio (plasma:platelets:RBCs) — the basis of massive transfusion.

Finally, prevent the lethal triad: hypothermia → acidosis → coagulopathy, each feeding the others. Hypothermia impairs clotting enzymes, poor perfusion drives lactic acidosis, and both cripple coagulation. Keep the patient warm (blankets, warm fluids, raise cabin temperature) — warming is a hemorrhage-control intervention, not a comfort measure.

Worked scenario and exam traps

A 25-year-old motorcyclist is found pale and diaphoretic after a high-speed crash. HR 124, BP 118/98, RR 26, anxious, with an open femur deformity bleeding briskly. Run MARCH: the brisk femoral bleed is massive hemorrhage — apply direct pressure, then a tourniquet high and tight if it does not stop, noting the time. The narrow pulse pressure (118/98) plus tachycardia is compensated Class II shock even though the systolic looks fine; do not be falsely reassured.

Establish IV/IO access, give TXA 1 g over 10 minutes, titrate small crystalloid boluses to a radial pulse, and keep him warm. Rapid transport to a trauma center.

High-yield traps:

• Normal blood pressure does not rule out shock. Tachycardia and narrowed pulse pressure precede hypotension; waiting for a low systolic delays treatment until Class III.
• A tourniquet that leaves a distal pulse is too loose and worsens venous bleeding — tighten until the pulse disappears.
• 'Wide open' fluids in uncontrolled hemorrhage dilute clotting factors, drop body temperature, and blow off clots. Use balanced blood products (1:1:1) when carried, or titrated crystalloid otherwise.
• Forgetting to keep the patient warm. Skipping hypothermia prevention actively feeds coagulopathy.
• Skin signs are an early window: cool, pale, clammy skin and delayed capillary refill flag hypoperfusion before vitals decompensate.