A patient develops hypotension and oxygen saturation of 88% within 15 minutes of starting a blood transfusion; what is the most likely diagnosis?

Diagnosis: Transfusion-Related Acute Lung Injury (TRALI)

The most likely diagnosis is Transfusion-Related Acute Lung Injury (TRALI), given the acute onset of hypotension and hypoxemia within 15 minutes of transfusion—this represents the classic presentation of non-cardiogenic pulmonary edema caused by donor anti-leukocyte antibodies. 1, 2

Key Diagnostic Features Supporting TRALI

The presence of hypotension rather than hypertension is the critical distinguishing feature that rules out Transfusion-Associated Circulatory Overload (TACO) and points directly to TRALI. 1, 2

Timing and Clinical Presentation

• TRALI characteristically presents within 1-2 hours after transfusion initiation, with maximum symptoms developing within 6 hours 3, 4
• The hallmark triad consists of: hypoxemia (SpO2 88%), dyspnea, and hypotension 1
• This 15-minute onset falls squarely within the typical TRALI timeframe 2, 5

Pathophysiologic Mechanism

• TRALI results from donor leukocyte antibodies (HLA class I, class II, or granulocyte-specific antibodies) interacting with recipient neutrophils 1, 2
• This causes granulocyte aggregation and complement activation in lung capillaries, leading to non-cardiogenic pulmonary edema 2
• The mechanism involves acute respiratory distress and cardiovascular instability, explaining both the hypoxemia and hypotension 1

Why Not the Other Options?

Acute Hemolytic Transfusion Reaction (Option A)

• While hemolytic reactions can present with hypotension and tachycardia, the prominent hypoxemia (SpO2 88%) and respiratory distress are not typical primary features 3
• Hemolytic reactions more characteristically present with hemoglobinuria, microvascular bleeding, and fever rather than isolated severe hypoxemia 3

Transfusion-Associated Circulatory Overload/TACO (Option B if referring to volume overload)

• TACO presents with hypertension (BP >100 mmHg), not hypotension 6, 1
• TACO shows cardiovascular changes suggesting fluid overload with elevated blood pressure 6
• TACO responds to diuretics and has elevated BNP/NT-proBNP levels 6
• The hypotension in this case definitively excludes TACO 1, 2

Allergic Reaction (Option C)

• Simple allergic reactions typically present with urticaria, pruritus, and bronchospasm 1
• Allergic reactions do not cause the severe hypotension and profound hypoxemia (SpO2 88%) seen in this case 1
• The severity of cardiovascular and respiratory compromise exceeds what would be expected from a standard allergic reaction 1

Immediate Management Algorithm

First Actions (Within Seconds)

1. Stop the transfusion immediately and maintain IV access with normal saline 1, 2
2. Administer 100% oxygen to address severe hypoxemia 1, 2
3. Call for help and prepare for potential intubation and mechanical ventilation 1

Hemodynamic Support

• Maintain adequate blood pressure with IV fluid resuscitation using normal saline or lactated Ringer's solution 1
• Critical pitfall to avoid: Do NOT administer diuretics—they are ineffective and potentially harmful in TRALI 1, 2
• Diuretics would only be appropriate for TACO (which presents with hypertension, not hypotension) 6, 1

Post-Stabilization

• Report the reaction to the blood bank immediately to remove the implicated donor from the pool 1
• Continue observation for at least 24 hours, as TRALI can evolve over the first 6-12 hours 1
• Send post-reaction blood samples for complete blood count, direct antiglobulin test, repeat crossmatch, PT, aPTT, and fibrinogen to exclude hemolytic reaction 1

Clinical Context and Prognosis

• TRALI is now recognized as a leading cause of transfusion-related mortality despite being underdiagnosed and underreported 1, 4, 7
• Most patients recover within 96 hours with appropriate supportive care 3
• The prognosis is substantially better than most other causes of acute lung injury when recognized and managed appropriately 8
• Most donors implicated in TRALI cases are multiparous women with anti-leukocyte antibodies 9