Exam 3: Lecture 22 - Blood loss and transfusions Flashcards
How do we calculate blood volume in mammalian species?
5-8% of total body weight is used to approximate blood volume
Which domestic species has the lowest blood volume (in ml/kg)?
Cats (47-66 ml/kg)
What is the total blood volume in canines?
86 (79-90 ml/kg)
How do we estimate blood loss during surgery?
-Cotton tipped applicator ~0.2 mL
-1 mL of blood = 1 gram of weight
-Don’t forget to check suction bottle, drapes, floor…. and talk to your surgeon!
A 4x4 inch, 12-ply woven sponge can absorb how much blood?
-Between 5 and 12.5 mL of blood
A 4x4 inch, 4-ply nonwoven sponge absorbs how much blood?
-Between 10-18.3 mL of blood
A 12x12-inch woven laparotomy sponge moistened with sterile saline solution before use can absorb how much blood?
-About 50 mL of blood
What are the goals of blood transfusion?
- Restore oxygen-carrying capacity
-Anemia
-Moderate blood loss - Restore blood volume after severe & acute hemorrhage (>20 mL/kg)
- Replace coagulation factors
What is the transfusion trigger?
-Concentration of Hb below which DO2 decreases to the point where anaerobic metabolism starts
What are the 2 basic reasons a transfusion may be needed?
-Anemia
-Coagulopathy
Transfusion triggers are based on
-PE findings & hematological values (e.g. PCV, Hb, platelet count & caogulation values)
What should be considered when hemoglobin concentration is below 7 grams per deciliter (hematocrit of 21%) in dogs and cats?
-Administering red cells to meet oxygen transport needs
It is best to maintain a Hct of _____ in surgical patients
21-25%
What drop in PCV is a transfusion indicated in?
-Acute drop to PCV < 20% = transfusion indicated
1 unit of blood = ____ mL
500 mL
With pRBCs, it takes approximately ____ to raise PCV by 1%
1 ml/kg
With whole blood, it takes approximately ___ to raise PCV by 1%
2 ml/kg
How fast should blood be given?
-Transfuse slowly for 1st 30 min., monitoring closely for any signs of transfusion reaction
-Can go higher during critical situations
-Go slower in cats, puppies & kittens
-Finish transfusion within 4 hours to prevent bacterial contamination & loss of function
What rate should blood be given?
-Whole blood or pRBCs can be given at a rate of 5-10 mL/kg/hr after initial 30 minutes of being given slowly
How do we administer a blood transfusion?
-Admin via a dedicated peripheral or jugular IVC
-Use aseptic technique
Can fluids and other medications be administered along with transfusion?
NO!! (except 0.9% NaCl)
Blood should be rewarmed to ____ degrees Celsius using a warm fluid bath (NOT microwave)
37-39 degrees C
The fluid administer set should be used with a
Filter
What should be avoided with transfusions?
-IVF pumps (ex: Heska) b/c can crush the RBCs
Canines have __ major blood groups labeled as ____, but the major antigen is ____
-8 major blood groups
-Labeled as DEA (dog erythrocyte antigen) 1-8
-Major antigen is DEA 1 (only antigen tested for)
Is blood typing required on 1st transfusion?
-No b/c dogs do not have naturally occurring antibodies
What is the best practice for blood transfusions?
-To blood type every recipient in the event a 2nd transfusion is needed a few days later & to conserve DEA negative blood for dogs that really need it
What are the feline blood types?
-3 main types: A, B, AB
-Majority of cats in the USA are type A
T/F all cats must be blood typed prior to transfusion
YES!!!! Very important
___ cat blood type is highly prevalent in Australia & among pure pred cats (i.e. exotic breeds)
Type B
What type cats have natural alloantibodies that will shorten RBC life if type B blood is given?
Type A cats
Type ___ cats have natural isoantibodies againdt type ___ -> causes fatal reaction even if only 1 mL of type ___ blood given!
Type B against type A, fatal if type A blood given
Type AB cats can receive what blood?
A or B blood types (universal recipients)
Type AB cats account for ___ % of the cat population
1%
What is a major crossmatch?
-Performed to detect antibodies in recipient’s serum that may agglutinate or lyse 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 tested w/ plasma from the donor
What is the gold standard for cross-matching?
-To cross match the donor & recipient prior to each transfusion as there are blood types that have not been recognized, and there is no type system for Mik (in cats)
What does a fresh whole blood transfusion do, and when must it be transfused?
-Transfused within 6-8 hours of collection
-Provides RBCs, WBCs, platelets, plasma, clotting factors
What do we typically use fresh whole blood transfusions for?
-Acute hemorrhage or life-threatening thrombocytopenia
What happens to fresh whole blood after 8 hours?
-It becomes stored whole blood & the platelets & coagulation factors are markedly reduced
What do we use packed red blood cell transfusions for?
-Indicated for anemic patients that are normovolemic & don’t need coagulation factors
-use “fresher” units for critically ill patients to avoid injury associated w/ prolonged storage
What is fresh frozen plasma (FFP)?
-Collected in citrate anticoagulant & separate plasma from whole blood within 8 hours of collection, store frozen for up to 1 year
When is fresh frozen plasma indicated?
-For inherited & acquired coagulopathies
What is the freezer life for FFP?
1 year from the draw date
-FFP becomes frozen plasma (FP) after 1 year & then remains useable as FL for the next 4 years
Frozen plasma does not contain the factors ____
5 and 8
What is Fresh plasma?
-Centrifuged to separate plasma from whole blood, transfuse within 4-6 hours of collection (after this, it is no longer fresh)
What is cryoprecipitate & cryosupernatant?
-Prepared from fresh frozen plasma, stored frozen for up to 1 year
-Concentrated source of labile factors VIII, XIII, vWF, and fibrinogen
What are the indications for cryoprecipitate & cryosupernatant?
-Hemorrhage or prophylaxis before invasive procedures in deficiency of vWF and factor VIII
What is platelet rich plasma?
-Plasma & platelets separated from RBCs after centrifugation (transfuse within 48 hrs of collection)
-Contains platelets & plasma
What are the indications for platelet rich plasma?
-Hemorrhage
-Prophylaxis before invasive procedure in severe thrombocytopenic or thrombocytopathic disorders
What are some transfusion complications?
Immediate
-Immunologic
-Non-immunologic
Delayed
-Immunologic
-Non-Immunologic
What are immediate immunologic effects?
-Hemolytic reactions
-Febrile reactions
-Allergic reactions
What are hemolytic reactions?
-Immediate immunologic effects
-Most severe but are rare & due to incompatible blood or intra-donor incompatibility in multiple transfusions
What is an example of a hemolytic reaction?
-Feline mismatched transfusions are ineffective & may cause life-threatening hemolytic transfusion reactions
What is a febrile reaction?
-Immediate immunologic reaction
-Any increase of one degree (Celsius) or more within 1-2 hours must be considered a febrile reaction due to white cell, platelet or plasma protein antibodies
What should you do if you suspect a febrile reaction is occurring?
-Stop the transfusion immediately
What is a transfusion allergic reaction?
-Immediate immunologic reaction
-Patient reacts to allergens in donor RBCs, platelets, granulocytes, plasma proteins - often complement - immunoglobulins
What are signs of a transfusion allergic reaction?
-Urticaria
-dyspnea
-Laryngeal edema
What should you do if you suspect a transfusion allergic reaction?
-Give diphenhydramine prophylaxis in patients w/ allergic tendencies, although often ineffective
-Stop transfusion immediately
-Epinephrine may be used for dyspnea or anaphylactic reaction
What are some immediate non-immunologic reactions?
-Circulatory overload
-Hypothermia
-Electrolyte imbalance
-Citrate intoxication (hypocalcemia)
What are some delayed immunologic effects?
-Delayed hemolytic reaction
-Graft vs. host
-Post-transfusion purpura
-Alloimmunization (antibody formation)
What are clinical signs to watch for during transfusion?
-Tachycardia
-Dysrhythmias
-Hypotension
-Tachypnea
-Dyspnea
-Tremors
-Emesis
-Urticaria or wheals
-Transient fever
-Hemolysis
-Hemoglobinemia
-Hemoglobinuria
What is important to note about clinical signs to watch for during transfusion?
-General anesthesia may mask some of these signs
-If in doubt, stop transfusion!
What is “xenotransfusions”?
-Transfusion of blood from another species
What are autologous transfusions?
-Administration fo blood to patient that was previously collected from that patient
-Decreased risk of transfusion reaction or transmission of disease
-Patient may donate blood preoperatively (or could be collected intra or postoperativey “washed” and administered back to patient)
