Massive Transfusion and the Lethal Triad in Trauma
A 29-year-old man is brought in after a high-speed motorcycle crash. He is hypotensive (BP 78/40), tachycardic (HR 138), and has a distended abdomen and unstable pelvis on exam. FAST is positive in the pelvis. He is intubated and receives 2 units of packed red cells and 2 L crystalloid in the trauma bay. He is taken emergently to the operating room. Over the next 90 minutes he receives 6 units PRBCs, 4 units FFP, and 1 unit platelets. Core temperature is 34.2°C, pH 7.12, INR 2.1, and ionized calcium is 0.78 mmol/L. He is oozing diffusely from surgical sites.
1. Identify the components of the lethal triad/tetrad present and explain how each worsens bleeding.
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This patient demonstrates the lethal triad plus hypocalcemia:
- Hypothermia (34.2°C) - impairs platelet function and clotting enzyme kinetics; each degree below 35°C reduces coagulation cascade activity.
- Acidosis (pH 7.12) - reduces activity of coagulation factors (especially the tenase and prothrombinase complexes) and impairs fibrin polymerization.
- Coagulopathy (INR 2.1) - dilutional and consumptive from massive transfusion and tissue injury; worsens microvascular bleeding.
- Hypocalcemia (ionized Ca 0.78) - citrate in stored blood chelates calcium, a required cofactor for the coagulation cascade; low ionized calcium impairs clot formation and also causes hypotension and arrhythmias.
Each element is self-reinforcing: bleeding causes hypothermia and acidosis, which worsen coagulopathy, which causes more bleeding.
2. Describe your immediate management priorities in the operating room.
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- Damage control resuscitation - activate the massive transfusion protocol with a balanced ratio (approximately 1:1:1 PRBC:FFP:platelets) rather than large-volume crystalloid.
- Correct hypocalcemia - give intravenous calcium (e.g., calcium gluconate or chloride) guided by ionized calcium; recheck frequently during massive transfusion.
- Rewarm - forced-air warming, warmed fluids and blood products, and raise ambient OR temperature; target normothermia.
- Correct acidosis - restore perfusion (the primary treatment) and continue resuscitation; reserve bicarbonate for severe refractory acidosis.
- Surgical control - damage-control laparotomy and pelvic stabilization (binder, packing, angioembolization) to stop the source.
- Adjuncts - consider tranexamic acid early in trauma hemorrhage, and viscoelastic testing (TEG/ROTEM) to guide product replacement.
The organizing principle is to stop the bleeding and reverse the physiologic derangements simultaneously, not sequentially.