Hemorrhagic Shock, Massive Transfusion and Damage Control Resuscitation

Hemorrhagic shock is circulatory failure from acute blood loss. Lose enough volume and the pump has less to work with. Preload drops, cardiac output drops, and oxygen delivery falls with them. The body fights back with vasoconstriction, tachycardia and a catecholamine release. In EMS, trauma is the most common cause. Obstetric, gastrointestinal and ruptured-aneurysm bleeding follow the same resuscitation logic. Only the source control changes.

• Trauma-induced coagulopathy: it shows up early. Consumption, endothelial injury, fibrinolysis, acidosis and hypothermia drive it. Every liter of crystalloid makes it worse.
• Lethal diamond: hypothermia, acidosis, coagulopathy and hypocalcemia feed each other. Some recent trauma literature adds hypocalcemia as a fourth component.
• Massive transfusion (MT): the hospital or EMS protocol defines it. The ABC score helps you predict the need early.
• Damage control resuscitation: stop the bleeding, limit crystalloid, give balanced blood products early, correct calcium and temperature, and move fast to definitive control.

Presentations

• Compensated: the BP looks normal or near normal, but the heart rate is up and the skin runs cool or pale. Anxiety and a narrow pulse pressure round it out. This is the easiest stage to miss.
• Decompensated: the BP is low, mentation changes, urine output drops and SpO₂ falls as shock progresses.
• Hidden bleeding: chest, abdomen, pelvis, thigh and retroperitoneum. A flat abdomen does not rule it out.

ABC Score

The ABC (Assessment of Blood Consumption) score gives one point each for penetrating mechanism, positive FAST, systolic BP of 90 mmHg or less, and heart rate of 120/min or more. A score of 2 or more points to massive transfusion. In the original trauma cohort, that cutoff had 75% sensitivity and 86% specificity. Use it to activate protocols early. Don't use it to delay them.

Red Flags

• SBP ≤90 mmHg, or a falling pulse pressure, after injury
• Heart rate ≥120/min; shock index (HR ÷ SBP) at or above the protocol threshold is a common trigger
• New confusion, agitation or decreasing responsiveness
• Cold, pale, mottled skin or delayed capillary refill
• Bleeding through dressings, pelvic or femur fracture, expanding hematoma or distended abdomen
• Hypothermia

You make this diagnosis at the bedside. Stop the bleeding and start resuscitating while the workup runs.

• Tension pneumothorax or cardiac tamponade: obstructive shock. Look for unequal breath sounds or muffled heart sounds, with distended neck veins. Distended neck veins are usually absent in hemorrhage.
• Neurogenic shock: after a spinal cord injury, you see warm, dry skin and bradycardia. Hemorrhage still has to be ruled out.
• Anaphylaxis: think hives, wheeze or facial swelling after an exposure.
• Sepsis: look for fever and a source of infection. The bleeding pattern is usually not traumatic.

1. Scene safety and mechanism: note the mechanism, time of injury and any known anticoagulant or antiplatelet use.
2. Control external bleeding: direct pressure and a hemostatic dressing; apply a tourniquet for extremity bleeding that will not stop, per local protocol. See Hemorrhage Control.
3. Keep warm: blankets and a dry environment; hypothermia worsens coagulopathy.
4. Position and oxygen: supine, with airway support and oxygen per protocol; avoid delaying transport for lengthy interventions.
5. Early notification: request ALS and a trauma-center destination, and tell the receiving team about the expected MT.
6. Reassess every 5 minutes: BP, heart rate, mentation and bleeding.

Doses vary by protocol; follow local protocols and medical direction.

• Hemorrhage control first (Paramedic/RN/CCT): use a tourniquet, junctional hemostatic packing or a pelvic binder, per protocol. Definitive control comes from surgery or an interventional procedure.
• Vascular access (Paramedic/RN/CCT): two large-bore IV or IO lines. See IO Access.
• Tranexamic acid early (Paramedic/RN/CCT): 1 g IV/IO over 10 min, then 1 g over 8 hr (CRASH-2 regimen), or a single 2 g dose where the EMS protocol specifies it. Give as early as possible; do not start more than 3 hours after injury unless protocol or medical direction says otherwise. See Tranexamic Acid.
• Massive transfusion: activate the MTP and transfuse red cells, plasma and platelets in a 1:1:1 ratio, the one used in PROPPR. Product type and ratio depend on your program. See Blood Components and Low-Titer O Whole Blood.
• Limit crystalloid: give only enough to keep a palpable radial pulse and intact mentation. Large crystalloid volumes dilute clotting factors. See Normal Saline.
• Calcium (Paramedic/RN/CCT): give calcium chloride 1 g IV slowly, or calcium gluconate 3 g IV, per protocol, when ionized calcium is low or with ongoing MT. Calcium chloride runs no faster than 100 mg/min (1 mL/min of 10%), never as a bolus, into a central or deep vein; stop at the site if infiltration occurs. Give calcium separately from bicarbonate and ceftriaxone. See Calcium Chloride and Calcium Gluconate.
• Permissive hypotension: aim for a restrained BP, meaning a palpable radial pulse with intact mentation, per protocol. Normal BP is not the target. The exception is traumatic brain injury (see Special Populations).

• Definitive hemorrhage control: surgery, angioembolization or resuscitative endovascular techniques, wherever they are available. Resuscitation keeps going during the procedure.
• Blood products: keep the MTP ratio going and reassess after each unit. Titrate plasma, platelets and fibrinogen to laboratory or viscoelastic results where you have them. See Fibrinogen.
• Vitamin K antagonist reversal: 4-factor prothrombin complex concentrate plus vitamin K, per protocol. The boxed warning is for arterial and venous thromboembolic complications. Factor Xa and dabigatran reversal follow the agent-specific protocol. See 4F-PCC.
• Calcium and temperature: watch ionized calcium during MT. Treat hypothermia actively, with warmed products and warming devices.
• Vasopressors: a bridge, not a fix. Use them when hemorrhage control isn't possible yet or perfusion fails. Norepinephrine per protocol. See Norepinephrine.
• Observation: after damage control, keep reassessing for abdominal compartment syndrome, coagulopathy and delayed bleeding.

• Destination: the highest-level trauma center in the system. If ground time runs long, choose air transport, per protocol.
• Continue in transit: keep products running through a warmer, and give calcium and TXA per protocol. Monitor BP, heart rate and SpO₂ at least every 5 minutes.
• Watch for: hypothermia, falling ionized calcium and tourniquet time. In the air, altitude adds its own problems: gas expansion, hypoxia, and vibration that limits monitoring.
• Blood product logistics: every unit runs on the program's cooler and time limit. Keep products warm per program, and document product type, unit numbers and times. Suspect a transfusion reaction (fever, hypotension, dyspnea, hives)? Stop the infusion, keep the line open and notify the receiving team.
• Handoff: time of injury, time and dose of TXA, products given (units and times), BP trend, tourniquet time, mechanism and anticoagulant use.

• Pediatrics: kids compensate well, then decompensate suddenly. Hypotension shows up late. Dose blood products by actual weight, per the program's pediatric massive-transfusion protocol. No verified mL/kg volume is given here. The labeled pediatric calcium chloride dose for hypocalcemia is 2.7–5 mg/kg IV, given slowly. Pediatric massive-transfusion calcium dosing depends on protocol, so use the local weight-based protocol. Pediatric TXA dosing for trauma is not established in the sources reviewed, so use the program's weight-based protocol for it. See Pediatric Shock and weight-based dosing.
• Pregnancy: resuscitate the mother first. Left uterine displacement and early delivery decisions follow obstetric protocol. Postpartum bleeding runs on the obstetric hemorrhage protocol, and that protocol uses TXA too.
• Older Adults: anticoagulant and antiplatelet use raise the bleeding risk. Beta-blockers and limited reserve blunt the response.
• Renal Impairment: the kidneys clear tranexamic acid, so reduce doses per the label and protocol.
• Patients on Anticoagulants: reversal depends on the agent. Warfarin is reversed with 4-factor PCC. Other agents follow the reversal protocol.
• Traumatic Brain Injury: avoid hypotension. BP targets come from the Brain Trauma Foundation guideline and the neurocritical care protocol. They do not come from permissive hypotension.

• TXA cautions: seizures and thromboembolic events are label warnings. Hypotension can follow a rapid push. Give the 1 g loading dose over 10 min, and weigh thrombotic risk in patients with known thrombosis.
• Error: treating a normal BP as reassurance. Compensated shock shows up as tachycardia and cool skin. Reassess perfusion, not just the BP.
• Error: pouring in large crystalloid volumes before control. Dilution worsens coagulopathy. Use products, and restrict crystalloid.
• Error: late TXA. Give it as early as possible after injury. Avoid starting it more than 3 hours after injury, unless protocol or medical direction says otherwise. In the CRASH-2 timing analysis, the benefit on bleeding death was greatest within 1 hour. Treatment after 3 hours appeared to increase bleeding death.
• Error: calcium gluconate in the same line as sodium bicarbonate or phosphate. The label says they are not physically compatible.
• Error: calcium chloride in the same line as ceftriaxone, or given IM or SC. Give calcium IV, slowly, into a central or deep vein. Stop if the patient has discomfort.
• Error: ignoring hypothermia and falling ionized calcium during MT. Both block clotting, even when products are going in.
• Error: assuming whole blood has proven superiority over components. In TOWAR (2026), 30-day mortality was 25.9% with whole blood and 20.5% with components (adjusted OR 1.24, 95% CI 0.87–1.76, P=0.24). That result is inconclusive. It is not proof of equivalence.