Lecture 22: Blood Loss & Transfusions (Exam 3) Flashcards
Why is blood loss a concern
Absolute hypovolemia -> decreased CO & hypotension -> decreased oxygen perfusion of tissue -> dev of metabolic acidosis
What % of total body weight is used to approximate blood volume in mammalian species
5 to 8%
Which domesticated species has the lowest blood vomue (ml/kg)
Cats
Fill out the following:
How is blood loss estimated during sx
- Cotton tipped applicator ~ 0.2 mL
- 1 mL of blood = 1 gram of weight
- Check the suction bottle, drapes, floor, & talk to the surgeon
What are the goals of transfusion
- Restore oxygen-carrying capacity (anemia & moderate blood loss)
- Restore blood volume after severe & acute hemorrhage ( > 20 mL/kg)
- Replace coagulation factors
Transfusion trigger = what
Concentration of Hb below which DO2 decreases to the point where anaerobic metabolism
Why are multiple factors used to determine the goals of transfusion
B/c it is difficult to assign an exact # @ which transfusion is implemented
What are the 2 basic reasons a transfusion may be needed
- Anemia
- Coagulopathy
What should be considered when hemoglobin concentration is below 7 grams per deciliter (hematocrit of 21%) in dogs & cats
Admin of RBC to meet oxygen transport
What PCV indicates transfusion
Acute drop to PCV < 20%
What equation is used to determine the volume of whole blood to administer to a dog? What about a cat?
approx 1 ml/kg of pRBCs is need to raise the PCV by what %
1%
How much whole blood is needed to raise the PCV by 1%
2ml/kg
How fast should blood be given
- Whole & pRBCs - a rate of 5 to 10 mL/kg/hr after the initial 30 min of being given slowly
- Start slowly (1/4 mL/kg/hr) during the first 30 min
- Can go higher during critical situations
- Go slower in cats, puppies, & kittens
- Finish the transfusion w/in 4 H to prevent bacterial contamination & loss of function
How can transfusions be admin
Peripheral or jugular IVC
T/F: Do not admin other fluids (except 0.9% NaCl) or medications along w/ transfusion
True
To what temps should stored blood be rewarmed to
37 to 39 degrees C
How many major blood groups are found in canine
8 types
What is the major antigen & the only one tested for
DEA 1
Why is blood typing not req on the first transfusion
B/c dogs do not have naturally occurring antibodies
What is the best blood typing practice
Blood type every recipient in the event a 2nd transfusion is needed a few days later & to conserve DEA neg blood for dogs that really need it
What are the blood types in cats
- A
- B
- AB
T/F: Cats do not have to be typed prior to transfusions
False; all cats must be typed prior to transfusions
What blood type are a majority of the cats in US
Type A
What do Type A cats have
Natural alloantibodies that will shorten RBC life if type B blood given
What do type B cats have
Natural isoantibodies against type A that can lead to a fatal reaction even if only 1 mL of type A blood is given
Which blood type in cats is considered the universal recipient
Type AB
Describe a major crossmatch
- Performed to detect antibodies in the recipient’s serum that may agglutinate or lyse the donor’s erythrocytes
- Checks compatibility of donor RBCs & recipient plasma
What is a minor crossmatch
- Detects antibodies in the donor plasma directed against recipient erythrocytes
- The red cells of the recipient are test w/ plasma from the donor
What is the gold standard of cross matching
To cross match the donor & recipient prior to each transfusion as there are blood types that have not been recognized & there is no type system for mik (in cats)
Describe fresh whole blood
- Transfused w/in 6 to 8 H of collection
- Provides RBCs, WBCs, platelets, plasma, & clotting factors
- Used for acute hemorrhage or life-threatening thrombocytopenia
What happens to fresh whole blood after 8 H
After 8 H it becomes stored whole blood & the platelets & coagulation factors are markedly reduced
What causes hematocrit to increase over the baseline value imm after transfusion & increase further w/in 24 H
Volume redistribution
Describe packed RBCs
- Indicated for anemic px that are normovolemic & don’t need coagulation factors
- Be sure to use “fresher” units for critically ill px to avoid injury assoc w/ prolonged storage
Describe fresh frozen plasma
- Collected in citrate anticoagulant & separate plasma from whole blood w/in 8 H of collection, store frozen for up to 1 Y
- Indicated for inherited & acquired coagulopathies
- Freezer life for FFP is 1 year from the draw data
- After 1 Y it become s frozen plasma & remains useable as FP for the next 4 years
- FP doesn’t contain factors 5 to 8 factors
What is fresh plasma
Centrifuged to separate plasma form whole blood & transfused w/in 4 to 6 H of collection
What is cryoprecipitate & cryosupernatant
- Prepared from fresh frozen plasma stored frozen for up to 1 Y
- Concentrated source of labile factors VIII, XIII, vWF, & fibrinogen
What are the indications of cryoprecipitate & cryosupernantant
Hemorrhage or prophylaxis before invasive procedures in deficiency of vWF & factor VIII
What is platelet rich plasma
- Plasma & platelets separated from RBCs after centrifugation
- Contains platelets & plasma
What are the indications for giving platelet rich plasma
- hemorrhage
- Prophylaxis before invasive procedure in severe thrombocytopenic or thrombocytopathic disorders
Describe hemolytic reactions
- Immediate immunologic effect
- Most severe but are rare & are due to incompatible blood or intra-donor incompatibility in multi transfusions
- Feline mismatched transfusions are ineffective & may cause life threatening hemolytic transfusion reactions
Describe febrile reactions
- Immediate immunologic reactions
- Any increase of one degree (celsius) or more w/in 1 to 2 hours must be considered a febrile reaction due to white cell, platelet, or plasma protein antibodies
- Stop transfusion immediately
Describe allergic rxns
- Immediate immunologic rxn
- Px reacts to allergens in the donor blood (red cells, platelets, granulocytes, & plasma proteins like complement immunoglobulins)
- Signs of urticaria, dyspnea, & laryngeal edema
Give diphenhydramine prophylaxis in px w/ allergic tendencies although this is often ineffective - Stop the transfusion immed
- Epinephrine may be used for dyspnea or anaphylactic rxn
List some immediate non-immunologic rxns
- Circulatory overload
- Hypothermia
- electrolyte imbalance
- Citrate intoxication (hypocalcemia)
What are some delayed immunologic effects
- Delayed hemolytic rxn
- Graft vs. host
- Post transfusion purpura
- Alloimmunization (antibody formation)
Give a list of clinical signs to watch for during a transfusion
What are xenotransfusions
- Transfusion of blood from another species
- Done w/ canine blood in felines
Describe autologous tranfusions
- Admin of blood to a px that was prev collected from that px
- Decreased risk of transfusion rxn or transmission of dx
- Px may donate blood preop or it could be collected intra or post op, “washed”, & admin back to the px
