Why is fresh frozen plasma (FFP) transfused in cases of massive blood loss?

Why Fresh Frozen Plasma is Transfused in Massive Blood Loss

Fresh frozen plasma (FFP) is transfused in massive blood loss primarily to replace coagulation factors that become critically depleted through consumption and dilution, thereby correcting coagulopathy and preventing life-threatening microvascular bleeding. 1

The Pathophysiology of Coagulopathy in Massive Hemorrhage

During massive blood loss, coagulopathy develops through three interconnected mechanisms that create the "lethal triad" when combined with hypothermia and acidosis 1:

• Consumption of clotting factors: Repeated attempts to form clots during ongoing hemorrhage deplete coagulation factors and platelets 1
• Dilutional coagulopathy: Modern red cell concentrates are suspended in optimal additive solution with negligible coagulation factor activity, so massive transfusion with these plasma-poor products progressively dilutes remaining clotting factors 1, 2
• Critical factor depletion timeline: Fibrinogen reaches critically low levels (<1.0 g/L) after approximately 150% blood volume loss, followed by other labile coagulation factors dropping to 25% activity after 200% blood volume loss 1

Specific Indications for FFP in Massive Bleeding

The American Society of Anesthesiologists provides clear criteria for FFP transfusion 1:

• Documented coagulopathy with active bleeding: PT >1.5 times normal, INR >2.0, or aPTT >2 times normal in the presence of excessive microvascular bleeding 1
• Empiric use when labs unavailable: Correction of coagulopathy in patients transfused with more than one blood volume (approximately 70 ml/kg) when coagulation tests cannot be obtained rapidly 1
• Early administration in anticipated massive hemorrhage: FFP should be considered after one blood volume has been lost to prevent rather than just treat established coagulopathy 1, 3

Optimal Dosing and Ratios

FFP must be given in adequate doses to achieve therapeutic effect 1:

• Standard dose: 10-15 ml/kg to achieve minimum 30% plasma factor concentration 1
• Ratio-driven resuscitation: Military experience supports 1:1:1 ratios of red cells:FFP:platelets in severe trauma with massive hemorrhage 3
• Minimum ratio: At least 1:2 plasma:red blood cell ratio should be maintained 1

Critical Limitations of FFP

While FFP is the standard source of coagulation factors, it has important constraints 1:

• Fibrinogen content is relatively low: Four units of FFP contain only approximately 2 g fibrinogen, compared to 4 g in two pools of cryoprecipitate 1
• Large volumes required: Established coagulopathy requires more than 15 ml/kg FFP to correct, which may be difficult to achieve rapidly 3
• Associated complications: FFP increases risk of transfusion-related acute lung injury (TRALI), acute respiratory distress syndrome, multiple organ failure, and infections 1

When FFP Should NOT Be Used

FFP is contraindicated in several common scenarios 1:

• Normal coagulation parameters (PT, INR, aPTT) without active bleeding 1
• Volume replacement or albumin augmentation 1
• Isolated thrombocytopenia without coagulopathy 1
• Mild-to-moderate coagulation abnormalities in non-bleeding patients before procedures 1

Adjunctive Therapies to Consider

When fibrinogen is specifically depleted (<1.0 g/L), cryoprecipitate or fibrinogen concentrate is more effective than FFP alone 1, 3:

• Cryoprecipitate provides more concentrated fibrinogen replacement 1
• Fibrinogen concentrate allows rapid targeted correction without large fluid volumes 3, 4
• Combination therapy (FFP plus fibrinogen concentrate) may provide superior clot formation compared to FFP alone 4

Common Pitfalls to Avoid

• Delaying FFP administration: Waiting for laboratory confirmation in obvious massive hemorrhage increases mortality; empiric administration is appropriate when massive transfusion is declared 3
• Inadequate dosing: Small volumes of FFP (1-2 units) are insufficient to correct established coagulopathy 1, 3
• Using FFP as sole therapy: FFP does not address platelet deficiency or isolated fibrinogen depletion effectively 1
• Ignoring the "lethal triad": FFP efficacy is dramatically reduced by hypothermia and acidosis, which must be corrected simultaneously 1, 3