# Blood Component Therapy and Massive Transfusion Protocols

## Introduction

Modern transfusion medicine relies on component therapy, which allows targeted replacement of specific blood elements. Understanding the indications, preparation, storage, and dosing of each component is essential for safe and effective transfusion practice. Massive transfusion protocols require coordinated efforts between the blood bank and clinical teams.

## Red Blood Cell Products

### Packed Red Blood Cells (pRBCs)

| Component | Storage | Shelf Life | Expected Effect | Key Indication |
|---|---|---|---|---|
| pRBCs | 1–6°C | 42 days | ↑ Hgb ~1 g/dL per unit | Anemia, hemorrhage |
| Platelets (apheresis) | 20–24°C, agitation | 5 days | ↑ plt 30,000–60,000/μL | Thrombocytopenia, bleeding |
| FFP | ≤ −18°C (thaw for use) | 12 months (frozen) | Replace all clotting factors | Coagulopathy, warfarin reversal |
| Cryoprecipitate | ≤ −18°C (thaw for use) | 12 months (frozen) | ↑ fibrinogen ~50–70 mg/dL | Hypofibrinogenemia |

Packed RBCs are prepared by centrifugation of whole blood and removal of plasma. They are stored in additive solutions (AS-1, AS-3, AS-5) at **1-6 degrees C** for up to **42 days**. Each unit has a hematocrit of approximately 55-65% and a volume of about 300 mL. One unit raises hemoglobin by approximately **1 g/dL** in a 70-kg adult. Indications include symptomatic anemia, acute hemorrhage, and a hemoglobin below 7 g/dL in most stable patients under a restrictive transfusion strategy.

### Modified RBC Products

**Leukocyte-reduced** RBCs undergo pre-storage filtration that removes over 99.9% of WBCs, reducing FNHTR, CMV transmission, and HLA alloimmunization. **Irradiated** RBCs receive 25 Gy of gamma or X-ray irradiation to prevent TA-GVHD, and are required for immunocompromised recipients, directed donations from relatives, and HLA-matched products. **Washed** RBCs have plasma proteins removed and are indicated for patients with severe allergic reactions or IgA deficiency with anti-IgA. **Volume-reduced** products have reduced supernatant volume for use in neonates and patients with volume sensitivity.

## Platelet Products

### Types and Preparation

**Whole blood-derived (WBD)** platelets are pooled from 4-6 whole blood donations using either the platelet-rich plasma or buffy coat method. **Apheresis** platelets come from a single donor and are equivalent to 4-6 WBD units while reducing donor exposure. Platelets are stored at **20-24 degrees C** with continuous agitation for up to **5 days** (or 7 days with bacterial testing or pathogen reduction). One apheresis unit is expected to raise the platelet count by **30,000-60,000/microL** in a 70-kg adult.

### Indications

Prophylactic transfusion is appropriate for platelet counts below 10,000/microL in stable patients, below 50,000/microL for invasive procedures, and below 100,000/microL for neurosurgery or ocular surgery. Therapeutic transfusion is given for active bleeding with thrombocytopenia or platelet dysfunction. Platelets are **contraindicated** in thrombotic thrombocytopenic purpura (TTP) and heparin-induced thrombocytopenia (HIT) unless life-threatening bleeding is present.

![Blood component separation from whole blood showing RBCs, buffy coat, and plasma layers](images/blood-component-separation.jpg)

## Plasma Products

### Fresh Frozen Plasma (FFP) and Thawed Plasma

FFP contains all coagulation factors, albumin, and immunoglobulins. It is frozen within **8 hours** of collection (FFP) or within 24 hours (FP24/PF24) and stored at or below **-18 degrees C** for up to 12 months. Once thawed, it is stored at 1-6 degrees C for up to **5 days** as thawed plasma, though some factor loss occurs. The dose is **10-15 mL/kg** for coagulopathy correction, typically 4 units for an adult. Indications include active bleeding with coagulopathy, warfarin reversal when PCC is unavailable, therapeutic plasma exchange for TTP, and DIC.

### Cryoprecipitate

Cryoprecipitate is prepared from controlled thawing of FFP at 1-6 degrees C, with the cold-insoluble precipitate collected. It contains concentrated **fibrinogen** (150-250 mg per bag), factor VIII, factor XIII, von Willebrand factor, and fibronectin. Once thawed, it must be transfused within **6 hours** (or 4 hours if pooled). A dose of 5-10 pooled bags raises fibrinogen by approximately 50-70 mg/dL. The primary indication is **hypofibrinogenemia** (fibrinogen below 100-150 mg/dL) with active bleeding or a planned procedure.

## Massive Transfusion Protocols

### Definition

**Massive transfusion** is defined as replacement of one or more total blood volumes within 24 hours, or transfusion of 10 or more RBC units within 24 hours. Alternative operational definitions include 4 or more RBC units in 1 hour or critical bleeding requiring ongoing transfusion support. Mortality in massive hemorrhage is **40-60%** without a protocolized approach.

### Protocol Components

**Activation criteria** rely on clinical judgment, with validated scoring systems (ABC score, TASH score) providing assistance. **Fixed-ratio component delivery** follows a **1:1:1 ratio** of RBCs to plasma to platelets, based on PROPPR trial data. Packages typically contain 6 RBC units, 6 plasma units, and 1 apheresis platelet unit. There is increasing interest in **whole blood**, particularly low-titer group O whole blood for early resuscitation in trauma.

### Laboratory Monitoring

**Point-of-care testing** includes ABG with lactate, hemoglobin, and ionized calcium. **Viscoelastic testing** (TEG/ROTEM) provides real-time assessment of clot formation, strength, and fibrinolysis to guide goal-directed transfusion. Monitoring should watch for **hypocalcemia** (from citrate toxicity), hyperkalemia, hypothermia, acidosis, and dilutional coagulopathy. Fibrinogen levels should be maintained above 150 mg/dL using cryoprecipitate or fibrinogen concentrate.

![Massive transfusion protocol activation flowchart showing component delivery packages](images/mtp-flowchart.jpg)

### Adjunctive Therapies

**Tranexamic acid (TXA)** is an antifibrinolytic that should be administered within 3 hours of injury (per the CRASH-2 trial) as a 1g IV bolus followed by 1g over 8 hours. **Calcium chloride or gluconate** replaces ionized calcium chelated by citrate in stored products. **Prothrombin complex concentrate (PCC)** is used for warfarin-associated hemorrhage, with 4-factor PCC preferred. **Recombinant factor VIIa** is used off-label in refractory hemorrhage but carries thrombotic risk.

## Special Populations

### Pediatric Transfusion

RBC volumes are calculated as **10-15 mL/kg** and platelet dose as 5-10 mL/kg. Dedicated aliquoting minimizes donor exposure in neonates. All cellular products for neonates under 4 months should be irradiated, CMV-safe, and hemoglobin S-negative.

### Obstetric Hemorrhage

Postpartum hemorrhage is the leading cause of maternal mortality worldwide. Massive transfusion protocols should be adapted for obstetric patients. RhD-negative women of childbearing potential should receive RhD-negative products when possible. TXA reduces maternal death due to bleeding when given within 3 hours, as demonstrated by the WOMAN trial.

![Viscoelastic testing (TEG) tracing showing normal hemostasis versus hyperfibrinolysis](images/teg-tracing.jpg)

## Clinical Pearls

Restrictive transfusion strategies with a hemoglobin trigger of 7 g/dL are appropriate for most stable, non-bleeding hospitalized patients and are associated with equivalent or improved outcomes. A 1:1:1 ratio of RBCs to plasma to platelets in massive transfusion mimics whole blood replacement and is associated with improved survival in trauma. Viscoelastic testing enables goal-directed transfusion therapy and reduces unnecessary blood product use during massive hemorrhage. Tranexamic acid should be administered within 3 hours of traumatic injury or onset of postpartum hemorrhage for maximal benefit.

## References

1. Holcomb JB, et al. Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial. *JAMA*. 2015;313(5):471-482.
2. Carson JL, et al. Clinical practice guidelines from the AABB: red blood cell transfusion thresholds and storage. *JAMA*. 2016;316(19):2025-2035.
3. CRASH-2 Trial Collaborators. Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage (CRASH-2). *Lancet*. 2010;376(9734):23-32.
4. Callum JL, et al. Bloody Easy 4: Blood Transfusions, Blood Alternatives and Transfusion Reactions. 4th ed. Ontario Regional Blood Coordinating Network; 2016.