BCA Fluid Management & Blood Transfusion 2 — Questions and Answers
Question 1: What is the most common cause of acute hemolytic transfusion reactions resulting in significant morbidity and mortality?
- Rh (D) incompatibility
- ABO incompatibility due to clerical or patient identification errors (Correct answer)
- Allergic reaction to donor plasma proteins
- Bacterial contamination of the blood product
Correct answer: ABO incompatibility due to clerical or patient identification errors
ABO-incompatible transfusions, most commonly caused by clerical or patient identification errors (wrong blood in tube, mislabeled samples), trigger complement-mediated intravascular hemolysis that can lead to DIC, acute renal failure, and death.
Question 2: Which hemodynamic parameter is most reliable for guiding goal-directed fluid therapy in mechanically ventilated patients?
- Central venous pressure (CVP) > 8 mmHg
- Pulmonary artery wedge pressure (PAWP)
- Stroke volume variation (SVV) or pulse pressure variation (PPV) > 13% (Correct answer)
- Urine output > 0.5 mL/kg/hr
Correct answer: Stroke volume variation (SVV) or pulse pressure variation (PPV) > 13%
Dynamic indices like SVV and PPV (>13% predicts fluid responsiveness) are superior to static preload measures like CVP or PAWP because they reflect the interaction between heart-lung during mechanical ventilation to predict volume responsiveness.
Question 3: The formula for Maximum Allowable Blood Loss (MABL) before red blood cell transfusion is required is:
- MABL = EBV × (Starting Hct − Minimum Acceptable Hct) / Starting Hct (Correct answer)
- MABL = Body weight × 70 mL/kg × Hematocrit
- MABL = (Target Hct − Current Hct) × EBV / 0.6
- MABL = Measured losses + Insensible losses + Urine output
Correct answer: MABL = EBV × (Starting Hct − Minimum Acceptable Hct) / Starting Hct
MABL = EBV × (Starting Hct − Minimum Acceptable Hct) / Starting Hct, where EBV (estimated blood volume) is typically 70 mL/kg for adults; this determines how much blood can be lost before the hemoglobin reaches the transfusion trigger.
Question 4: Current evidence-based massive transfusion protocols for hemorrhagic trauma recommend which blood product ratio?
- 1:1:1 ratio of FFP:Platelets:pRBC (Correct answer)
- 2:1:1 ratio of pRBC:FFP:Platelets
- 4:2:1 ratio of pRBC:FFP:Platelets
- pRBC alone until hemorrhage is surgically controlled
Correct answer: 1:1:1 ratio of FFP:Platelets:pRBC
The PROPPR trial demonstrated that a 1:1:1 ratio of plasma:platelets:pRBC resulted in better 24-hour hemostasis and trend toward improved 30-day survival compared to 1:1:2, supporting balanced resuscitation that mimics whole blood.
Question 5: Hypocalcemia during massive blood transfusion is primarily caused by which mechanism?
- Red blood cells consume calcium for cellular metabolism during storage
- Citrate preservative in blood products chelates ionized calcium, reducing its bioavailability (Correct answer)
- Dilutional effect from large volumes of calcium-free crystalloid co-administered
- Hypothermia causes ionized calcium to shift intracellularly
Correct answer: Citrate preservative in blood products chelates ionized calcium, reducing its bioavailability
Citrate (sodium citrate) is used as an anticoagulant preservative in blood products; during massive transfusion, the liver cannot metabolize citrate fast enough, leading to accumulation and chelation of ionized calcium, causing hypocalcemia and myocardial depression.
Question 6: Fresh Frozen Plasma (FFP) transfusion is most appropriately indicated for which clinical scenario?
- Volume replacement in active hemorrhagic shock when crystalloids are unavailable
- Correction of coagulopathy from multiple factor deficiencies (e.g., liver disease, DIC) or when specific factor concentrates are unavailable (Correct answer)
- Prophylactic correction of a mildly elevated INR (1.5-2.0) before elective central line placement
- Reversal of systemic heparin anticoagulation after cardiopulmonary bypass
Correct answer: Correction of coagulopathy from multiple factor deficiencies (e.g., liver disease, DIC) or when specific factor concentrates are unavailable
FFP contains all coagulation factors and is indicated for multiple factor deficiencies (liver failure, DIC, massive transfusion) or when specific factor concentrates are unavailable; it is not indicated for prophylactic correction of mild coagulopathy or heparin reversal (use protamine).
Question 7: How is Transfusion-Associated Circulatory Overload (TACO) best differentiated from Transfusion-Related Acute Lung Injury (TRALI)?
- TACO typically occurs more than 6 hours after transfusion; TRALI occurs within 6 hours
- TACO is associated with hypoxia; TRALI typically has normal oxygen saturation
- TACO responds to diuretic therapy with improvement; TRALI does not improve with diuretics (Correct answer)
- TACO causes fever and rigors; TRALI is an afebrile reaction
Correct answer: TACO responds to diuretic therapy with improvement; TRALI does not improve with diuretics
TACO is hydrostatic pulmonary edema from volume overload and responds to diuretics with improvement in oxygenation and chest X-ray; TRALI is non-cardiogenic pulmonary edema from immune-mediated capillary leak that does not respond to diuretics.
BCA Fluid Management & Blood Transfusion 2
What is the most common cause of acute hemolytic transfusion reactions resulting in significant morbidity and mortality?