Transfusion Medicine Study Notes

I. TRANSFUSION MEDICINE

Overview

• Blood transfusion usage in the United States:

  • Approximately 21 million blood components are transfused each year.

• Main clinical uses:

  • Management of major surgical procedures.

  • Management of traumatic injuries.

  • Treatment of medical conditions requiring regular transfusion.

• Transfusion demographics:

  • Low-income countries: Up to 54% of transfusions are given to children under 5 years old.

  • High-income countries: Most frequently transfused patient group is individuals over 60 years old.

• Definition of transfusion therapy:

  • A broad term encompassing all aspects of transfusion.

• Transfusion blood classification:

  • Considered a form of transplantation.

• Primary goals of transfusion:

  • Restore oxygen-carrying capacity in patients.

  • Restore hemostasis (with platelets and coagulation factors).

Types of Transfusion Practices

• Fresh blood transfusion:

  • Blood less than 24 hours old from the time of collection.

• Autologous transfusion:

  • Blood collected from a patient for re-transfusion back into the same individual.

  • Commonly used post-operatively.

• Multiple transfusion:

  • Repeated transfusion of blood over a long duration (months or years).

  • Commonly indicated for:

  • Cancer patients.

  • Patients on dialysis.

  • Patients with thalassemia.

  • Hemolytic disease of the fetus and newborn (HDFN).

  • Patients with various blood disorders.

• Massive transfusion:

  • Refers to a number of units transfused in 24 hours that exceeds the recipient’s blood volume (approximately 10 units for adults).

• Emergency transfusion:

  • Required for patients who are rapidly and uncontrollably bleeding (e.g., from vehicular accidents).

Types of Blood for Transfusion

• Type O Negative:

  • Recommended for women of childbearing age to prevent Rh sensitization.

• Type O Positive:

  • Commonly given to Rh negative older males.

• Neonatal transfusion:

  • Premature infants frequently require small transfusion volumes to replace blood drawn for laboratory tests.

  • Recommended blood requirements:

  • Fresh blood (less than 7 days old).

  • Must maximize oxygen content (increased 2,3-DPG and Potassium levels).

  • Should be CMV negative through leukoreduction.

  • May require irradiated blood, washed with normal saline before transfusion.

Transfusion in Oncology

• Iatrogenic anemia:

  • Caused by decreased hematopoietic cell production due to chemotherapy, necessitating component transfusion.

• Consequences of Immunosuppression:

  • Patients have a higher risk of Graft-versus-Host Disease (GVHD), where the transplanted organ/blood attacks the patient.

• Transfusion support:

  • Required for kidney, heart, and liver transplantation, as recommended based on organ type.

Priorities in Massive Transfusion

• Hypovolemia correction:

  • Use colloid or crystalloid solutions for both massive and emergency transfusion cases.

• Oxygen delivery:

  • Optimize the oxygen-carrying capacity of the blood.

• Hemostasis:

  • Maintain hemostasis utilizing platelets and coagulation factors.

• Metabolic balance:

  • Correct or avoid metabolic disturbances during transfusion.

• Volume maintenance:

  • Maintain intravascular volume using colloids or crystalloids.

II. BLOOD COMPONENTS

Whole Blood

• Clinical use:

  • Used to replace loss of both red blood cell (RBC) mass and plasma volume.

• Indication:

  • Rarely used unless in cases of rapidly bleeding patients.

• Expected effects:

  • 1 unit raises hematocrit by approximately 3% and hemoglobin by approximately 1 g/dL (may take up to 48-72 hours).

• Contraindications:

  • Patients with severe chronic anemia (as their body compensates by increasing plasma volume which can lead to pulmonary edema).

Packed Red Blood Cells (PRBC)

• Primary indication:

  • For patients with decreased oxygen-carrying capacity.

  • Includes conditions such as:

  • Decreased bone marrow production (e.g., aplastic anemia).

  • Decreased RBC survival (e.g., hemolytic anemia).

  • Surgical procedures.

• Therapeutic effect:

  • Increases RBC mass typically within 1 hour.

  • Results in an increase in hematocrit of 3% and hemoglobin of 1 g/dL.

• Contraindications:

  • Well-compensated anemia and nutritional anemia are not indications for transfusion.

Clinical Conditions and Hemoglobin Threshold for Transfusion

• Hemodynamically stable ICU patients:

  • Threshold is 7 g/dL.

• Orthopedic surgery:

  • Threshold is 8 g/dL.

• Cardiac surgery:

  • Threshold is 7.5 g/dL.

• Acute coronary syndrome:

  • Threshold is between 8-10 g/dL.

• Stable coronary artery disease:

  • Threshold is 8 g/dL.

• Heart failure:

  • Threshold is between 7-8 g/dL.

• Acute bleeding (hemodynamically stable):

  • Threshold is 7 g/dL.

• Cancer patients on treatment:

  • Threshold is between 7-8 g/dL.

• Transfusion-dependent thalassemia:

  • Threshold is between 9-10.5 g/dL (up to 12 g/dL for patients with cardiac complications).

• Symptomatic patients with comorbidities:

  • Threshold is between 8-10 g/dL.

• Asymptomatic patients without comorbidities:

  • Threshold is 7 g/dL.

III. BLOOD COMPONENT INDICATIONS SUMMARY

IV. IRRADIATED BLOOD COMPONENTS

• Radiation dose:

  • 1,500–2,500 cGy.

• Mechanism:

  • Radiation decreases the mitogenic capacity of T cells, rendering them immunoincompetent.

• Main purpose:

  • Prevention of Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD).

  • High-risk groups for TA-GVHD include:

  • Patients with congenital immunodeficiency (e.g., DiGeorge syndrome, SCID).

  • Bone marrow transplant recipients.

  • Donations from first-degree relatives due to shared HLA antigens increasing the risk of immune response against recipient tissues.

V. ALTERNATIVES TO BLOOD TRANSFUSION

• Factor VIII:

  • Used for the treatment of hemophilia A.

  • Recombinant human activated Factor VIII controls bleeding episodes in hemophilia A and B patients with inhibitors.

• Factor IX:

  • Treatment for hemophilia B.

• Antithrombin Concentrate:

  • Used for treating hereditary antithrombin deficiency that causes venous thrombosis.

• Recombinant Activated Protein C:

  • Indicated for acquired deficiency such as DIC and sepsis.

• Immune Serum Globulin (ISG):

  • For patients with congenital hypogammaglobulinemia, prophylaxis for hepatitis, ITP, and Myasthenia Gravis.

• Normal Serum Albumin:

  • Used for plasma volume expansion, hypovolemic shock, and conditions like hypoproteinemia, as well as in surgery, trauma, and burns.

• Rh Immune Globulin (Rhogam):

  • Protects Rh-negative mothers from Rh-positive babies, indicated in cases of miscarriage, delivery, abortion of an Rh-positive child, or transfusion of Rh-positive cells.

VI. BLOOD ADMINISTRATION AND SAFETY PRACTICES

• Major causes of transfusion-related deaths:

  • Clerical error poses significant risks.

• Blood filtration requirement:

  • All blood components must be filtered using a 170–260 µm filter to prevent infusion of clots and debris formed during storage.

• Initial transfusion rate:

  • Blood components infused slowly for the first 10–15 minutes.

• Maximum transfusion duration:

  • Must be completed within 4 hours with periodic monitoring (every 15 minutes) of vital signs.

• Monitoring and Transfusion Support:

  • Vital signs monitoring is essential and should be frequent during transfusion.

  • Rapid transfusion support utilizing blood warmers when necessary.

• Approved diluents:

  • Only 0.9% isotonic saline and 5% albumin are preferred; Ringer’s Lactate is not recommended.

• Hospital Transfusion Committee:

  • Has primary responsibility for peer review of blood usage and transfusion reactions.

  • Functions to recommend changes in transfusion practices and improve blood utilization to enhance patient care and transfusion safety.

  • Membership includes groups responsible for ordering and administering blood products.