When to transfuse packed red blood cells (RBCs) in a patient with dengue fever?

Packed RBC Transfusion in Dengue Fever

In dengue patients, transfuse packed RBCs only for hemorrhagic shock (systolic BP <90 mmHg, HR >110 bpm) or hemoglobin <7 g/dL with hemodynamic instability—not based on platelet count or minor bleeding alone. 1, 2

Clinical Decision Algorithm

Immediate Transfusion Required (Regardless of Hemoglobin)

• Hemorrhagic shock: Systolic blood pressure <90 mmHg, heart rate >110 bpm, or bleeding >150 mL/min 1, 3
• Unresponsive to crystalloid resuscitation: After 2 liters of isotonic crystalloid without hemodynamic improvement 1, 3
• Signs of inadequate tissue oxygen delivery: Elevated lactate, low pH, or evidence of organ ischemia 1, 2

Hemoglobin-Based Thresholds for Stable Patients

• Transfuse at Hb <7 g/dL in hemodynamically stable dengue patients without active bleeding 2, 4
• Consider Hb <8 g/dL threshold if patient has underlying ischemic heart disease or acute coronary syndrome 2, 4
• Rarely indicated when Hb >10 g/dL unless ongoing hemorrhage or severe cardiopulmonary disease 1

Dengue-Specific Considerations

What Makes Dengue Different

Thrombocytopenia alone is NOT an indication for RBC transfusion in dengue—platelet transfusion addresses bleeding risk from low platelets, while RBC transfusion addresses oxygen-carrying capacity 5. The two are distinct clinical decisions.

• Bleeding in dengue occurs more commonly with platelet counts <20,000/μL, but this indicates need for platelet transfusion, not RBC transfusion 5
• Upper gastrointestinal bleeding is the most common severe hemorrhage in dengue and may require RBC transfusion if hemodynamically significant 6
• Medical management with blood component support (when indicated) is the mainstay—endoscopic hemostasis is not effective in dengue-related GI bleeding 6

Critical Phase Monitoring

During dengue's critical phase (typically days 3-7), monitor for:

• Plasma leakage signs: Hemoconcentration, pleural effusion, ascites—these predict unfavorable outcomes 7
• Cardiopulmonary dysfunction: Associated with worse prognosis and may lower transfusion threshold 7
• Active bleeding sites: Mucosal hemorrhages, GI bleeding, or other significant blood loss requiring transfusion 8, 7

Transfusion Strategy

Administration Protocol

• Single-unit transfusions: Give one unit at a time in stable patients, reassess hemoglobin and clinical status after each unit 2, 3
• Avoid volume overload: Do not use RBC transfusion for volume expansion when oxygen-carrying capacity is adequate 1
• Monitor closely: Check hemoglobin before and after each unit, along with vital signs and clinical assessment 1

Massive Hemorrhage Protocol

If massive bleeding develops (>50% blood volume in <3 hours):

• Activate massive transfusion protocol with 1:1:1 ratio (RBCs:plasma:platelets) 2, 3
• Transfuse immediately without waiting for laboratory values 1, 2
• Use group O RBCs if type-specific blood unavailable within 15-20 minutes 1

Common Pitfalls to Avoid

Do not transfuse RBCs prophylactically based on low platelet count alone—this is inappropriate and exposes patients to transfusion risks without benefit 5. In one study, 31 of 96 dengue patients received inappropriate platelet transfusions, and similar logic applies to RBC transfusions 5.

Do not rely solely on hemoglobin concentration in acute bleeding—hemoglobin may remain falsely elevated despite significant blood loss due to inadequate fluid resuscitation or hemoconcentration from plasma leakage 1, 7.

Recognize transfusion-transmitted dengue risk—during outbreaks in endemic areas, donated blood may transmit dengue virus, causing severe thrombocytopenia in recipients 9. This is a rare but documented complication.

Risk-Benefit Assessment

Transfusion carries inherent risks that must be weighed against benefits:

• Transfusion-related acute lung injury (TRALI), circulatory overload, and immunomodulation 3, 4
• Increased infection risk and potential thromboembolism 3
• In dengue specifically, transfusion-transmitted infection during outbreaks 9

A restrictive transfusion strategy (Hb <7 g/dL) is as effective as liberal strategy (Hb <10 g/dL) in critically ill patients, including those with dengue, and reduces transfusion-related complications 2, 4.