Question

The "lethal triad" (deadly triad) associated with massive blood transfusion classically comprises hypothermia, coagulopathy and acidosis. Which of the following is NOT a component of this classic lethal triad?

• A. Hyperkalemia
• B. Coagulopathy
• C. Hypothermia
• D. Hypocalcemia

Hint:

Triad = hypothermia, coagulopathy, acidosis - potassium is not in it.

Answer 1

The Correct Option is A

Step 1: Define the lethal triad.
The classic lethal/deadly triad of massive transfusion and major trauma is hypothermia + coagulopathy + acidosis. These three feed back on one another, worsening bleeding and mortality.

Step 2: Map the metabolic complications of massive transfusion.
Stored blood is cold (hypothermia), citrate-anticoagulated (chelates calcium to hypocalcemia), dilutes clotting factors and platelets (coagulopathy), and leaks potassium from aged red cells (hyperkalemia), while citrate metabolism and tissue hypoperfusion contribute to acid-base shifts.

Step 3: Match options to the triad.
Coagulopathy and hypothermia are bona-fide triad members. Hypocalcemia, although a real transfusion complication, is the metabolic stand-in often paired with the triad. Hyperkalemia is a transfusion complication but is NOT one of the classic triad components.

Step 4: Choose the exception.
The indicator that does not belong to the classic lethal triad is hyperkalemia.

Key fact: Lethal triad = hypothermia, coagulopathy, acidosis; hyperkalemia is a separate transfusion-related electrolyte hazard.