Small Animal Medical Nursing: Blood Product Transfusions

Introduction and Technician Responsibilities

• Veterinary technician responsibilities in transfusion medicine encompass the entire process from collection to monitoring:

  • Donor collections.

  • Separation and storage of blood products.

  • Administration of the transfusion.

  • Continuous patient monitoring.

Indications for Transfusion Medicine

• Blood transfusions (Whole Blood or Red Blood Cells) are indicated for:

  • Acute hemorrhage.

  • Chronic anemia.

  • Hemolytic anemia.

• Platelet transfusions are indicated for:

  • Severe thrombocytopenia accompanied by hemorrhage.

  • Thrombocytopenia in patients requiring surgery.

• Plasma transfusions are indicated for:

  • Coagulopathy (clotting disorders).

  • Hypoalbuminemia (low albumin levels).

  • Failure of passive transfer of immunity.

Blood Donor Selection and Collection Procedures

• Donor Criteria:

  • Animals must be healthy.

  • Temperament must be suitable for handling and collection.

  • Must have an adequate Packed Cell Volume ($PCV$).

  • Must have appropriate body weight and Total Protein ($TP$).

  • Must have good access to the jugular vein.

  • Must undergo thorough infectious disease screening.

• Collection Protocol:

  • The donor is sedated if necessary; however, sedation is often not required for dogs once they are accustomed to the routine.

  • Surgical preparation of the collection site is mandatory.

  • The primary collection site for both dogs and cats is the jugular vein.

  • Collection must be performed rapidly and without interruption to maintain product integrity.

Pre-Transfusion Testing and Cross-matching

• Blood Typing: Determining the specific blood group of the donor and recipient.

• Antibody Screen: Testing for specific Red Blood Cell ($RBC$) antibodies.

• Cross-matching procedures:

  • Major Cross-match: Checks for agglutination reactions between the donor’s $RBC$s and the recipient’s plasma.

  • Minor Cross-match: Checks for agglutination reactions between the donor’s plasma and the recipient’s $RBC$s.

• Testing equipment mentioned: Rapid Vet-H, DMS Laboratories, Flemington, New Jersey.

Blood Collection Calculations and Volumes

• Calculations for donation amounts should be based on lean body weight.

• The maximum donation amount is generally $10$ to $15\%$ of the animal's total blood volume.

• Specific donation guidelines by species:

  • Canine: $13$ to $17\,mL/kg$ of body weight.

  • Feline: $11$ to $15\,mL/kg$ of body weight.

  • Equine: Approximately $\sim 16\,mL/kg$ of body weight.

Anticoagulants and Storage Solutions

• For immediate use:

  • Sodium citrate is the preferred anticoagulant.

• For storage purposes:

  • Citrate-phosphate-dextrose ($CPD$).

  • Citrate-phosphate-dextrose-adenine ($CPDA$).

Blood Products and Characteristics

• Fresh Whole Blood ($WB$):

  • Provides $RBC$s for oxygen delivery.

  • Provides plasma proteins for hypoproteinemia and oncotic volume expansion.

  • Contains viable platelets (useful for severe bleeding).

  • Contains all clotting factors.

  • Usage: Must be used within $6\,hours$ of collection to retain all properties, especially viable platelets and labile factors.

  • Indications: Severe bleeding, coagulopathies ($DIC$, warfarin), factor deficiencies, severe anemia, and severe hypoproteinemia.

• Packed Red Blood Cells ($PRBCs$ or $pRBC$):

  • Supplies red blood cells only.

  • Shelf life: Roughly $35$ to $42\,days$.

  • Indications: Anemia in patients with a normal plasma volume.

• Fresh Frozen Plasma ($FFP$):

  • Frozen within $8\,hours$ of collection.

  • Stored for up to $1\,year$.

  • Contains albumin and all clotting factors.

  • Labile clotting factors included: Factor $5$, Factor $8$, and von Willebrand Factor ($vWF$).

  • Vitamin K-dependent clotting factors included: Factors $2$, $7$, $9$, and $10$.

  • Indications: Coagulopathy of unknown origin, hypoproteinemia, and need for colloid expansion.

  • Note: Does NOT supply viable platelets.

• Frozen Plasma ($FP$):

  • Can be kept for $2$ to $5\,years$ if stored correctly.

  • Note: Does not supply labile clotting factors.

  • Indications: Anticoagulant rodenticide toxicity, hypoproteinemia, colostrum replacement, and volume expansion.

• Cryoprecipitate ($Cryo$):

  • Supplies labile clotting factors: Factor $5$, Factor $8$, and $vWF$.

  • Indications: von Willebrand Disease ($vWD$) and Hemophilia A.

• Cryoprecipitate Poor Plasma ($CPP$ or Cryopoor plasma):

  • Contains albumin and Vitamin K-dependent clotting factors ($2$, $7$, $9$, and $10$).

  • Indications: Anticoagulant rodenticide and hypoproteinemia.

Administration Guidelines

• Preparation:

  • Blood temperature should be less than or equal to body temperature ($\le \text{body temp}$).

  • Plasma should be thawed in a water bath (approximately $1\,hour$ for frozen plasma).

• Incompatibilities: Do not administer blood with:

  • Hypertonic or hypotonic solutions.

  • Calcium-containing solutions.

• Volume and Flow Rates:

  • Determine volume/rate by estimating the patient's blood loss and total blood volume.

  • Start the transfusion slowly while monitoring closely.

  • The entire transfusion should be completed in < 4\,hours.

  • Canine plasma dose: $10$ to $15\,mL/kg$.

  • Feline plasma dose: $5$ to $8\,mL/kg$.

Patient Monitoring and Parameters

• Monitoring frequency: Every $15\,min$. The first $15\,min$ is the most critical period.

• Parameters to monitor:

  • Physical exam and vital signs.

  • Packed Cell Volume ($PCV$).

  • Blood lactate levels.

Transfusion Reactions

• Acute Allergic Hypersensitivity:

  • Signs include erythema, urticaria (hives), pruritus, or full anaphylaxis.

• Acute Hemolytic Transfusion Reactions:

  • Occurs quickly due to incompatible blood.

  • Clinical signs: Hemoglobinemia, hemoglobinuria, progressive anemia, lack of $PCV$ increase, systemic inflammatory response, disseminated intravascular coagulation ($DIC$), shock, and cardiovascular collapse.

• Delayed Hemolytic Transfusion Reactions:

  • Can result from improper handling of the blood product.

• Non-immunologic Reactions:

  • Febrile nonhemolytic reaction (fever): The most common reaction.

  • Transfusion-related acute lung injury ($TRALI$).

  • Transfusion-associated circulatory overload ($TACO$): Caused by large volumes or rapid delivery. Signs include pulmonary congestion, coughing, increased respiratory rate, respiratory distress, and vomiting. Risk is higher in patients with pre-existing cardiac dysfunction.

• Miscellaneous Reactions:

  • Transmission of infectious diseases.

  • Bacterial contamination.

  • Citrate toxicity.

  • Vascular overload: Requires reduction of rate to approximately $1\,mL/kg/hr$.

• Clinical Precautions during Transfusion:

  • Vomiting is a potential reaction.

  • Food, water, and medications should be withheld during the transfusion process.

Feline Blood System

• Blood Types: The AB system ($Type A$, $Type B$, and $Type AB$) and the $Mik$ antigen.

• Frequency and Distribution:

  • Types vary by geographic region and breed.

  • In the United States, > 90\% of cats are $Type A$.

  • $Type B$ is more common in specific purebred cats.

• Natural Alloantibodies:

  • Found in all cats by a few weeks of age.

  • $Type B$ cats have antibodies against $Type A$.

  • $Type A$ cats have antibodies against $Type B$.

• Reaction Severity:

  • $Type A$ cat given $Type B$ blood: Results in mild reactions on the first transfusion.

  • $Type B$ cat given $Type A$ blood: Can be fatal even on the first transfusion.

• Clinical Signs of incompatible transfusion ($Type A$ blood to $Type B$ cat):

  • Can occur after as little as $1\,mL$ of blood is administered.

  • Vocalization, salivation, urination, defecation.

  • Depression progressing to recumbency.

  • Bradycardia, arrhythmias, seizures, apnea, and death.

Neonatal Isoerythrolysis in Felines

• Occurs in $Type A$ or $Type AB$ kittens born to $Type B$ dams.

• Maternal anti-A antibodies are ingested via colostrum, causing hemolysis in the kitten.

• Clinical Signs:

  • Acute death.

  • "Fading kittens."

  • Tail-tip necrosis.

Canine Blood System

• Blood Types: Dog Erythrocyte Antigens ($DEA$) labeled $1.1, 1.2, 3, 4, 5, 6, 7, 8$.

• Common Types: $DEA 1.1$ negative is the most common.

• Reaction Characteristics:

  • Reactions are unlikely to occur on the initial transfusion.

  • Pre-existing isoantibodies develop after a previous transfusion.

  • Cross-matching is mandatory for any dog with a history of prior blood transfusions.