**Question:** A 25-year-old man involved in a motorcycle accident incurs a laceration to his thigh. The bleeding is stabilized en route to the hospital, but on arrival, he is noted to have orthostatic hypotension and his hematocrit is 21%. He receives 2 units of PRBCs. As the first unit is nearly finished transfusing, he becomes febrile and hypotensive. Urine output ceases. The serum above the clot in a red top phlebotomy tube is pink. Which of the following complications of transfusion has most likely occurred in this man?

A. Transfusion-associated circulatory overload (TACO)
B. Transfusion-related acute lung injury (TRALI)
C. Transfusion-associated immunomodulation (TAM)
D. Transfusion-associated acute kidney injury (TRAKI)

**Correct Answer:**

**Core Concept:** Transfusion-related acute lung injury (TRALI) is a severe complication of transfusion, characterized by acute onset respiratory distress and hypotension. It is caused by the introduction of leukocytes from the donated blood into the recipient's circulation, which can lead to lung inflammation and injury.

**Why the Correct Answer is Right:**

In this scenario, the patient receives two units of packed red blood cells (PRBCs) during transfusion. As the first unit is nearly finished, the patient becomes febrile and hypotensive. The change in urine output and the pink serum above the clot in a red top phlebotomy tube are also indicative of a transfusion-related complication.

**Why Other Options are Invalid:**

A) Transfusion-associated circulatory overload (TACO) is a less severe complication, where fluid overload leads to pulmonary edema and shortness of breath. Although the patient is hypotensive and has respiratory distress, TACO is less likely because the patient's urine output is not reduced, and there is no mention of fluid overload.

B) Transfusion-associated acute lung injury (TRALI) is more consistent with the patient's respiratory distress, hypotension, and reduced urine output. Leukocytes in the transfused blood can cause lung inflammation and injury, leading to these symptoms.

C) Transfusion-associated immunomodulation (TAM) is a less specific term for TRALI. It refers to the modification of the recipient's immune system by the introduction of foreign components from the transfused blood. However, TAM is not explicitly mentioned in the scenario, so TAM cannot be definitively ruled out.

D) Transfusion-associated acute kidney injury (TRAKI) is unlikely given the lack of a reduction in urine output, which is a key feature of TRAKI.

**Clinical Pearls:**

1. Transfusion-associated acute lung injury (TRALI) is a critical complication that requires immediate attention, as it can be life-threatening. Blood products should be transfused slowly to minimize the risk of TRALI.
2. Monitoring urine output is an essential aspect of transfusion management. Reduced urine output would suggest