13.1 External Hemorrhage Control: Tourniquets, Wound Packing & Pelvic Binders

13.1 External Hemorrhage Control: Tourniquets, Wound Packing & Pelvic Binders

Trauma Hemostasis & The Lethal Triad of Trauma

Exsanguinating hemorrhage represents the leading cause of preventable death in both civilian trauma and tactical medicine. Under the Canadian Paramedic Competence Framework (CPCF Appendix A #27B) and national trauma guidelines, the primary survey prioritizes the immediate mitigation of catastrophic external bleeding (<C>ABC paradigm) before addressing the airway. Failure to arrest torrential hemorrhage initiates the Lethal Triad of Trauma, a self-propagating pathophysiological cascade consisting of hypothermia, metabolic acidosis, and coagulopathy.

The Pathophysiological Triad

1. Hypothermia (Core Body Temperature <35°C): Hemorrhagic shock causes profound peripheral hypoperfusion, curtailing cellular aerobic metabolism and decreasing mitochondrial adenosine triphosphate (ATP) and heat production. Furthermore, the infusion of ambient-temperature intravenous crystalloids and environmental exposure rapidly exacerbate core cooling. Hypothermia impairs clotting factor enzyme kinetics: coagulation protease complexes (e.g., tenase and prothrombinase) exhibit exponential declines in catalytic activity for every 1°C decrease below normal body temperature, leading to platelet dysfunction and clotting factor inhibition independent of factor concentrations.
2. Metabolic Acidosis (pH <7.20, Base Deficit >-6 mmol/L): Massive volume depletion reduces circulating erythrocyte mass and capillary hydrostatic pressure. Tissues suffer generalized dysoxia, forcing cells into anaerobic glycolysis. Lactic acid accumulates systemically. As systemic pH drops below 7.20, the enzymatic conversion of prothrombin to thrombin on activated platelet membranes is severely curtailed (decreasing by up to 50–70% at pH 7.0), accelerating bleeding.
3. Coagulopathy (Trauma-Induced Coagulopathy [TIC]): TIC is driven by a combination of consumption of circulating platelets and fibrinogen, hemodilution from crystalloid resuscitation, enzymatic inactivation from acidosis and hypothermia, and hyperfibrinolysis mediated by endothelial release of tissue plasminogen activator (tPA). This creates a vicious circle where worsening hemorrhage exacerbates shock, hypothermia, and acidosis, which in turn accelerate coagulopathy.

                    [ Catastrophic Hemorrhage ]
                                | 
                                v
                     [ Tissue Hypoperfusion ]
                                | 
       +------------------------+------------------------+
       |                                                 |
       v                                                 v
[ Anaerobic Metabolism ]                       [ Decreased Heat Production ]
[ Lactic Acid Accumulation ]                   [ Environmental Cooling / IV Fluids ]
       |                                                 |
       v                                                 v
 [ Acidosis (pH <7.2) ]                         [ Hypothermia (<35°C) ]
       |                                                 |
       +------------------------+------------------------+
                                |
                                v
                [ Trauma-Induced Coagulopathy ]
                (Enzyme inhibition, platelet failure)
                                |
                                v
                   [ Refractory Exsanguination ]

---

Stepped External Hemorrhage Control Paradigm

Canadian paramedic protocols dictate an aggressive, stepped approach to external extremity hemorrhage based on the tactical environment, severity of hemorrhage, and anatomical location:

1. Direct Manual Pressure & Pressure Dressings

Immediate, firm, focused digital or manual pressure applied directly over the transected vessel using gloved hands or sterile gauze represents the initial action for compressible wounds. Direct pressure should be maintained continuously while equipment is staged. If bleeding is controlled, a sterile pressure dressing (e.g., elastic bandage, Israeli-type emergency bandage) is secured over the wound. However, in torrential, high-pressure arterial spurting from major limb vessels, manual pressure is frequently insufficient and must not delay tourniquet deployment.

2. Commercial Windlass Tourniquets (CAT / SOFTT)

Commercial windlass tourniquets—such as the Combat Application Tourniquet (CAT) and the Special Operations Forces Tactical Tourniquet (SOFTT)—are the gold standard for extremity arterial hemorrhage.

[!CAUTION] Never Loosen or 'Burp' a Tourniquet Prehospital: Once a tourniquet is placed to control life-threatening hemorrhage, primary care paramedics must never loosen, cycle, or release the windlass to 'check for perfusion.' Loosening washes acidotic, hyperkalemic, and microthrombotic effluent into central circulation while immediately restarting exsanguinating hemorrhage and dislodging fragile clots.

---

Junctional Wound Packing with Bioactive Hemostatic Gauze

Junctional anatomical zones—the groin (inguinal crease/femoral triangle), axilla, and base of the neck—represent transition areas where extremity tourniquets cannot achieve mechanical circumferential compression. Severe arterial or deep venous hemorrhage in these regions mandates immediate wound packing.

Bioactive Hemostatic Agents

Modern Canadian ambulance services utilize hemostatic dressings impregnated with pro-coagulant compounds:

• Kaolin-Impregnated Gauze (e.g., QuikClot Combat Gauze): Kaolin is an inert inorganic mineral that rapidly activates Factor XII (Hageman factor) of the intrinsic coagulation pathway, accelerating downstream thrombin generation and fibrin clot formation.
• Chitosan-Based Dressings (e.g., Celox, ChitoGauze): Chitosan is a positively charged polysaccharide derived from crustacean chitin. It electrostatically attracts negatively charged erythrocytes and platelets, forming a dense, adherent pseudo-clot independent of the physiological coagulation cascade. It functions effectively even in hypothermic or heparinized patients.

Procedural Technique for Junctional Packing

1. Clear and Expose: Expose the wound completely and quickly sweep away pooled blood, large surface clots, and foreign debris to expose the bleeding vascular defect.
2. Identify the Source: Direct a gloved finger deep into the wound cavity to locate the pulsating vessel or focal source of active hemorrhage.
3. Deep Cavity Packing: Unroll the hemostatic gauze and, using a finger-over-finger technique, pack the gauze directly against the bleeding vessel deep in the base of the wound cavity. Continue packing tightly until the entire wound cavity is densely packed under mechanical tension.
4. Uninterrupted Manual Pressure: Maintain uninterrupted, continuous manual pressure directly over the packed wound for a minimum of 3 full minutes (or 5 full minutes if using standard non-impregnated plain gauze). Do not release pressure to 'peek' at the wound during this period.
5. Secure Pressure Dressing: Following the pressure interval, apply a tight elastic pressure bandage or junctional compression strap over the packed wound to maintain continuous compression during transport.

---

Pelvic Circumferential Compression Devices (PCCD) & Pelvic Ring Fractures

High-energy blunt trauma mechanisms—including pedestrian-automobile impacts, motorcycle collisions, falls from height (>3 metres), and high-speed motor vehicle crashes—frequently generate severe disruptions of the pelvic ring (e.g., anteroposterior compression 'open-book' fractures, lateral compression fractures, vertical shear injuries).

Pathophysiology of Exsanguinating Pelvic Trauma

Disruption of the pelvic ring expands the internal volume of the true pelvis exponentially. This expansion tears the dense, low-pressure presacral and paravesical venous plexuses (responsible for 85–90% of pelvic hemorrhage) as well as branches of the internal iliac artery (e.g., superior gluteal, internal pudendal, obturator arteries). Because the retroperitoneum is a compliant, non-rigid anatomical space, it can sequester 3 to 5 litres of blood before intrinsic tissue pressures tamponade the bleeding, resulting in fatal hemorrhagic shock before visible external bleeding occurs.

Biomechanics & Landmarking of Pelvic Binders

Commercial Pelvic Circumferential Compression Devices (PCCDs), such as the SAM Pelvic Sling, restore pelvic stability and decrease pelvic volume, re-approximating bone fragments to facilitate venous tamponade.

   [ INCORRECT PLACEMENT: Iliac Crests ]       [ CORRECT PLACEMENT: Greater Trochanters ]
              (High Placement)                              (Proper Biomechanics)

           /---------------\                             /---------------\ 
          |   Iliac Wing    |                           |   Iliac Wing    |
          \-------v-------/                             \---------------/
          [ BINDER APPLIED HERE ]                                |
          Forces crests inward, levers                           v
          sacroiliac joint OPEN!                        [ BINDER APPLIED HERE ]
                  |                                  (Across Greater Trochanters)
                  v                                              |
       [ Paradoxical Splaying ]                                  v
    [ Worsens Internal Bleeding ]                    [ Closes Pelvic Ring Concentrically ]
                                                     [ Tamponades Retroperitoneal Bleeding ]

[!IMPORTANT] Strict Prohibition of Pelvic 'Rocking' or Springing: In suspected pelvic trauma, primary care paramedics must palpate the pelvis only once for structural tenderness or gross asymmetry. Paramedics must never vigorously rock, compress-distract, or spring the iliac crests to test for mechanical instability. Repetitive manual testing breaks fragile newly formed fibrin clots in the retroperitoneal venous plexus, converting a potentially stabilizing hematoma into lethal free retroperitoneal exsanguination.

---

Clinical Scenario: Stepped Hemostasis in High-Energy Polytrauma

A 34-year-old male motorcyclist is struck broadside by an SUV at 80 km/h. Paramedics arrive to find the patient supine on the roadway, pale, diaphoretic, and confused (GCS 12: E3, V4, M5). Vital signs: BP 78/42 mmHg, HR 138 bpm (weak, thready radial pulses), RR 28/min, SpO2 93% on room air.

1. Primary Survey (<C>ABC): The primary paramedic identifies bright red, pulsatile arterial blood jetting from an open, mangled wound of the mid-right thigh with visible bone fragments. Immediate firm direct manual pressure is placed over the wound while the second paramedic unrolls a Combat Application Tourniquet (CAT).
2. Tourniquet Deployment: The CAT is placed 6 cm proximal to the wound on the thigh, all slack is removed from the band, and the windlass is rotated 3 full turns. Arterial pulsatile jetting ceases, but moderate bright red bleeding continues to well from the wound bed, and a faint popliteal pulse remains palpable.
3. Dual Tourniquet Application: Recognizing that a single tourniquet has failed on a thick, muscular thigh, Paramedic 2 immediately applies a second CAT directly proximal to and touching the first. After two turns of the second windlass, all bleeding halts completely, and the distal pulse is abolished. The time ('TK 18:04') is clearly recorded on both tourniquets.
4. Secondary Bleed & Junctional Packing: A deep, jagged 5 cm laceration in the left inguinal crease (groin junction) is actively oozing dark venous blood under pressure. Because an extremity tourniquet cannot be placed across the groin, Paramedic 1 rapidly sweeps pooled blood, packs kaolin-impregnated hemostatic gauze tightly into the base of the wound cavity using finger-over-finger pressure, and maintains continuous, firm manual pressure for 3 full minutes without interruption. Bleeding is fully controlled, and an overlying pressure bandage is secured.
5. Pelvic Ring Stabilization: Physical examination of the pelvis reveals gross tenderness over the pubic symphysis. The crew refrains from any pelvic rocking. A SAM Pelvic Sling is positioned precisely over the greater trochanters and tensioned until the buckle clicks (150 N). The patient's feet are bound in gentle internal rotation.
6. Resuscitation & Transport: The patient is packaged on a scoop stretcher, covered with warm blankets to prevent hypothermia, provided high-flow oxygen, and transported rapidly to the regional Level 1 trauma centre under prehospital trauma team bypass notification.

---

Exam Pitfalls & High-Yield Hemostasis Pearls

• Placing Tourniquets Over Joints: Tourniquets applied over the knee or elbow fail to compress vessels running through protected anatomical interosseous grooves; always place 5–7 cm proximal to the injury or high-and-tight.
• Leaving Slack in the Tourniquet Band: Failing to pull the tourniquet band maximally tight before twisting the windlass causes the windlass to run out of travel before sufficient arterial occlusion pressure is reached, creating a venous tourniquet that worsens hemorrhage.
• Placing Pelvic Binders Over the Iliac Crests: Binders placed over the iliac crests splay the pelvic ring open and accelerate exsanguination; always verify landmarking over the greater trochanters.
• Testing Pelvic Stability Repeatedly: Never perform pelvic rocking or springing. One gentle palpation is all that is clinically indicated.
• Prematurely Checking Packed Wounds: Peeking under hemostatic gauze before completing the mandatory 3 minutes of continuous manual pressure disrupts nascent platelet-fibrin cross-linking and restarts hemorrhage.