Understanding when and why to transfuse blood products is critical for anesthesia providers. The decision to transfuse is based on a careful assessment of the patient's clinical condition, laboratory results, and the type of surgery being performed.
Indications for RBC Transfusion
- Hemoglobin <7 g/dL in hemodynamically stable patients (restrictive strategy); <7.5 g/dL in cardiac surgery and <8 g/dL in orthopedic surgery or pre-existing cardiovascular disease
- Symptomatic anemia
- Massive hemorrhage or trauma
- Hemodynamic instability despite fluid resuscitation
Before the threshold is reached, the question is how much blood the patient can lose first. Estimated blood volume (EBV) is about 70 mL/kg in an adult man, 65 mL/kg in an adult woman, 80 mL/kg in an infant, and 85-90 mL/kg in a term neonate. Maximum allowable blood loss (MABL) = EBV x (starting hematocrit - lowest acceptable hematocrit) / starting hematocrit. For a 70 kg man (EBV 4,900 mL) starting at a hematocrit of 40% with a floor of 30%, MABL is about 1,225 mL.
In the app: the Master Anesthesia app's Blood calculator (Calculators, then Blood) runs this arithmetic from the patient profile: enter weight, the starting hemoglobin or hematocrit, and the lowest value you will accept, and it returns the estimated blood volume and the maximum allowable blood loss. Its Need to transfuse planner then projects the hemoglobin as blood loss climbs and estimates the packed red cells needed to bring it back above your floor. See masteranesthesia.com/features/maximum-allowable-blood-loss-calculator.
Indications for Platelet Transfusion
- Platelet count <50,000/microliter in surgical patients or with active bleeding (<100,000/microliter for neurosurgery or ocular surgery; <10,000/microliter for prophylaxis in stable, non-bleeding patients)
- Active bleeding or need for invasive procedures
- Bleeding or urgent surgery with platelet dysfunction (antiplatelet drugs, uremia, cardiopulmonary bypass) despite a normal count; prophylactic transfusion for antiplatelet therapy alone is not recommended, and in antiplatelet-associated intracerebral hemorrhage it worsened outcomes (PATCH trial)
Indications for FFP Transfusion
- INR >1.5 and active bleeding
- Warfarin reversal in emergency surgery when four-factor PCC is unavailable (PCC is preferred)
- Coagulopathy due to liver disease or DIC
Indications for Cryoprecipitate Transfusion
- Fibrinogen <100 mg/dL, or <150-200 mg/dL during massive hemorrhage or obstetric bleeding
- Management of massive transfusion protocols
- Hemophilia A or von Willebrand disease only when factor concentrates are unavailable; factor XIII deficiency
| Component | What it provides | Indications for transfusion |
|---|---|---|
| Red blood cells | Oxygen delivery to tissues; the most commonly transfused component | Hemoglobin <7 g/dL in stable patients, <7.5 g/dL in cardiac surgery, <8 g/dL in orthopedic surgery or cardiovascular disease; symptomatic anemia; massive hemorrhage or trauma; hemodynamic instability despite fluid resuscitation |
| Platelets | Clotting function in thrombocytopenia or platelet dysfunction | Platelet count <50,000/µL in surgical patients (<100,000/µL for neurosurgery or ocular surgery; <10,000/µL for prophylaxis in stable patients); active bleeding or need for invasive procedures; platelet dysfunction with bleeding (antiplatelet drugs, uremia, bypass), not routine prophylaxis for antiplatelet therapy |
| Fresh frozen plasma | Clotting factors, correcting coagulopathies | INR >1.5 with active bleeding; warfarin reversal in emergency surgery when PCC is unavailable; coagulopathy from liver disease or DIC |
| Cryoprecipitate | Concentrated fibrinogen, factor VIII, and von Willebrand factor | Fibrinogen <100 mg/dL (<150-200 mg/dL in massive or obstetric hemorrhage); management of massive transfusion protocols; hemophilia A or von Willebrand disease only when factor concentrates are unavailable |
