Blood Transfusion Flashcards
what changes have the RCVS made to make blood products widely available for primary care small animal practitioners?
taking of blood from healthy donors with the permission of the owner with the intention of passing it to a recipient with immediate or anticipated need
VMD licensed blood banks
what blood products are available for dogs in the UK?
whole blood packed red blood cells (PRBCs) fresh frozen plasma frozen plasma cryoprecipitate cryoprecipitate poor plasma
what blood products are available for cats in the UK?
no feline per blood banks
whole blood can be obtained locally
how can whole blood be obtained for cats?
locally via:
local donor colonies
cats of consenting colleagues, clients, friends and family
donors from local animal register
why can more be done with canine blood than with feline blood?
canine blood can be collected in advance and so can be processed much more easily
this enables it to help more patients
what is produced by a hard spin in a centrifuge of whole blood?
packed RBC (precipitate) fresh frozen plasma (supernatant)
what is fresh whole blood?
blood used within 6 hours of collection
what is found within fresh whole blood?
physiological concentrations of RBC
some functional platelets
proteins
coagulation factors
how must fresh whole blood be stored?
at room temp
what is the PCV of fresh whole blood?
~40% (as normal)
what is stored whole blood?
blood over 8 hours old
how can stored whole blood be stored?
2-6 degrees C
up to 21 days
what is found in stored whole blood?
no functional platelets
loss of labile clotting factors
what are labile clotting factors?
factor 8
VWF
how are packed red blood cells separated from plasma?
by centrifugation
what is the PCV of packed red blood cells?
higher than that of whole blood (70-80%)
how should PRBCs be stored?
2-6 degrees C
42 days
how is fresh frozen plasma stored?
-18 degrees
less than 1 year
what is found in fresh frozen plasma?
all coagulation factors (including labile)
physiological concentrations of albumin and other plasma proteins
what is frozen plasma?
FFP that is >1 year old or that has been thawed and refrozen either intentionally or by accident
what is found in frozen plasma?
stable coagulation factors
labile factors lost
how is FP stored?
below -18 degrees for up to 5 years
ho is cryoprecipitate made?
by slowly and partially thawing FFP which is then centrifuged again
cryoprecipitate is collected from second centrifugation
what is found in cryoprecipitate?
fibrinogen
VIII
vWF
(labile clotting factors)
what patients may benefit from transfusion therapy?
those with diseases that result in a deficiency of a blood constituent may benefit from transfusion
what are some examples of diseases which may benefit from transfusion therapy?
hypovolaemic anaemia (e.g. blood loss) euvolaemic anaemia (e.g. IMHA) coagulopathies (e.g. rodenticide toxicity)
is transfusion therapy helpful for thrombocytopenia, thrombopathia or hypoalbuminaemia?
unclear
it is often tried but expensive and rarely effective in curing the problem
volume overload is likely before issue is corrected
when are blood products indicated for anaemic patients?
if there are clinical signs of anaemia (i.e. patient is not compensating for the anaemia)
is the decision to use blood products based on PCV values alone?
no
what are the clinical signs of anaemia?
weakness
tachycardia
tachypnoea
indirect measures of poor oxygen delivery (e.g. high blood lactate)
what product is the ideal one to use for transfusion?
most closely replaces that which is missing
what is the benefit of using the blood product that most closely replaces that which is missing?
reduces the likelihood of transfusion complications
allows blood products to be used most effectively
when does blood type need to be considered?
if giving whole blood or PRBCs
how are antibodies for RBC acquired in dogs?
may be naturally occurring or acquired through previous sensitisation
how do dogs gain antibodies to RBC through sensitisation?
due to a previous blood transfusion
what happens if the recipients RBC antibodies match antigens on the donor RBC?
immune response leading to immune mediated transfusion reaction
what are the signs of transfusion reaction?
fever tachycardia dyspnoea muscle tremors vomiting weakness collapse haemoglobinemia haemoglobinuria
what is the name of the dog erythrocyte antigen?
DEA
wat are the types of DEA that can be found by labs?
1, 3, 4, 5 and 7
within each type of DEA what types are there?
positive and negative
what is the most antigenic DEA?
DEA 1 - most concerning and most common cause of immune mediated transfusion reaction
what is the only DEA we can type for in clinical practice?
DEA 1
do dogs possess naturally occurring antibodies to DEA 1?
no
describe the RBC of a DEA1 positive dog
RBC possesses DEA1 antigen
describe the RBC of a DEA1 negative dog
RBC does not possess DEA1 antigen nor does it’s plasma contain any anti-DEA1 alloantibodies
what are the other main canine blood types?
Dal (positive and negative)
what Dal blood type do most dogs have?
positive
what dogs are Dal negative?
dalmations
can Dal be typed for in house?
no
if giving dalmatians a blood transfusion where should it come from?
ideally from another dalmatian or they need to be cross matched
are there any other blood types in dogs apart from Dal and DEA?
yes but not clinically relevant
what blood should DEA1 negative dogs receive?
only DEA1 negative
what blood should DEA1 positive dogs receive?
either 1 positive or negative
what blood type can be given to dogs in their first transfusion?
un-typed blood can be given in the first transfusion
why can un-typed blood be given to dogs on their first transfusion?
they do not possess naturally occurring alloantibodies
can reactions still be seen after a dogs first blood transfusion?
yes - delayed
what blood can be given to an un-typed canine patient in an emergency?
DEA1 negative
why should DEA1 blood be given sparingly?
risk of shortages
what should be collected from the patient prior to emergency transfusion?
blood sample
why does a blood sample need to be collected before transfusion?
allows for more accurate blood typing as this is not possible after transfusion
describe the RBC and plasma of ‘sensitised’ DEA1 negative dogs
RBC doesn’t possess DEA1 antigen but it’s plasma does contain anti-DEA1 antibodies
what happens if a DEA1 negative dog is exposed to DEA1 positive blood?
over the course of a few days it will develop anti-DEA1 antibodies
shortens lifespan of transfused RBC
what happens if a dog with anti-DEA1 antibodies is exposed to DEA-1 positive blood for a second time?
it will have a transfusion reaction
what can happen during subsequent transfusions even if there has been blood typing and appropriate transfusion?
can still lead to reactions due to sensitisation to the remaining DEAs or other RBC antigens
what is required before subsequent transfusions?
cross matching
what are the blood types found in cats?
A
B
AB
do cats have naturally occurring alloantibodies?
yes - present in the plasma
does antibody formation in cats require previous exposure through transfusion or pregnancy?
no
what can cat antibodies cause?
fatal transfusion reactions upon first transfusion and are also responsible for neonatal isoerthrolysis
what other blood types exist in cats?
those that cannot be routinely tested for (e.g. Mik)
describe the RBC and plasma of a type A cat
RBC has A surface antigen
plasma contains anti -B alloantibodies (weak and low in number)
describe the RBC and plasma of a type B cat
RBC possesses B surface antigen
plasma contains lots of anti-A antibodies
describe the RBC and plasma of a type AB cat
RBC possesses both A and B surface antigens
have no antibodies against either antigen in plasma
what blood should cats be given?
that which matches their blood type
what blood can be given to type AB cats?
AB preferably
if not available type A is the next best choice as it contains low anti-B antibodies
do all donors and recipients of blood transfusions in cats need to be typed?
yes - even in an emergency or on first transfusion as transfusion mismatches can be fatal
describe how a transfusion reaction may occur in a cat
type B cat is exposed to type A blood. Naturally occurring alloantibodies will trigger severe transfusion reaction
this does not require a history of prior exposure or sensitisation
what effect can subsequent transfusions have in cats regardless of appropriate transfusion or blood typing?
can still lead to reaction due to sensitisation against RBC antigens outside the A-B blood group system
what is cross matching used for?
to determine serological compatibility between patient and donor
what are you looking for during cross matching?
agglutination which indicates the animals blood types are incompatible
what are the 2 tests included in cross matching?
major crossmatch
minor crossmatch
what is included in a major crossmatch test?
recipients serum and donors RBC
what is included in a minor crossmatch?
donors serum and recipients RBC
when should crossmatching be performed?
if the recipient has had a transfusion more than 4 days ago
there is a history of transfusion reaction
recipients transfusion history is unknown
recipient has been previously pregnant
ideally all feline transfusions (especially if no blood typing)
dalmations
how can blood products be obtained?
from blood banks
practices enrolled in share schemes
local collection
what else can often be provided by pet blood banks or share schemes?
collection and processing services
equipment needed for transfusion that isn’t regularly held in practice
what are the qualities required for a good canine or feline donor?
should be healthy generally between 1 and 8 years no history of travel receiving routine preventative health care never have received a transfusion good jugular veins
what are the specific qualities required for a good canine donor?
large (>25kg)
well tempered
clear disease screens
what are the specific qualities required for a good feline donor?
large (>4kg) BCS 4-6 blood typed clear disease screen foe FIV, FeLV, mycoplasma haemofelis ideally indoor
what is involved in the blood donation process?
clinical history and full physical exam to confirm good health
blood sample taken
clip hair from area over both jugular veins and apply EMLA
clean and prep the area for aseptic technique
use an anticoagulant at the correct ratio
what should a patients blood sample be checked for before blood donation?
PCV TS hematology biochemistry typing infectious disease screen
can cats and dogs donate conscious?
dogs should be able to and any that couldn’t maybe aren’t the best choice for donors
cats need sedation
what are the donation volume limits for cats?
10-12 ml/kg
what are the donation volume limits for dogs?
15 ml/kg
what should happen to the blood during collection?
gently roll to mix with anticoagulant
what do cats need following blood donation?
IVFT over 60-120 mins
what volume of fluids should cats receive following donation?
double volume of blood collected
when should food and water be offered after donation?
straight away for dogs and after sedation has worn off for cats
should animals have activity restricted after blood donation?
yes - 24 hours
how is open donation performed?
using syringes /butterfly catheter and syringe with a pre-calculated amount of anti coagulant in
what is the issue with open donation?
one or more additional sites for potential bacterial contamination
what is the advantage of closed donation?
the only exposure is when the needle is uncapped to perform venepuncture
do both open and closed donation need anti-coagulant?
yes
what animals is open donation used in?
felines
small dogs
what animals is closed donation used in?
large dogs only
is the shelf life of blood longer for blood collected through open or closed donation?
closed
before administering blood products what should you do?
visually inspect bag to check for breakage, leakage, discolouration and gas bubbles
how do frozen blood products need to be prepared before they are given to a patient?
gently thawed in a warm water bath
should whole blood or PRBCs be warmed before administration?
can be warmed very gently in patients at risk of hypothermia but otherwise unnecessary
what is the risk of warming blood products?
can cause pre-transfusion haemolysis
what should you record about the patient before administering blood?
record baseline parameters and monitor throughout
how should blood be administered to a patient?
using blood giving set or IVFT giving set with an in line filter
IO if desperate
how much blood should be administered to patients?
10-20 ml/kg
by how much does PCV increase by for every 2 ml/kg of blood given?
approx 1%
what types of blood filters are available?
built into drip chamber of giving set
in-line filter that can be inserted into giving sets
how should blood administration be started?
slowly 1ml/kg/hr for 20 mins to check for transfusion reaction
how rapidly should blood be given after the first 20mins?
over 4-6 hours
should patients be fed during transfusion?
no
what can be administered through the same catheter as the blood?
nothing other than 0.9% saline as it could cause haemolysis or blood clots
what must be done when a patient has has a transfusion?
all future / present healthcare providers should be notified that the patient has received a transfusion
what parameters should you monitor on a patient during a transfusion?
attitude/mentation rectal temp pulse rate and quality RR and character MM and CRT plasma and urine colour
how often should patients be monitored during a transfusion?
prior to
every 15 mins during
1, 12 and 24 hours after
when should PCV/TS be checked?
prior to
oncompletion of transfusion
12-24 hours collowing transfusion
what are the 3 main causes of immunologic transfusion reactions?
antigen-antibody sensitivity reaction (IgG and IgM mediated)
cytokines from product storage/leukocytes within product
allergic/hypersensitivity reaction (IgE mediated)
what are examples of non-immunological transfusion reactions?
volume overload citrate intoxication coagulopathy/thrombosis ammonia intoxication bacterial contamination of the unit pre-transfusion haemolysis
what is the most severe type of immunologic transfusion reaction?
antigen-antibody sensitivity reaction (IgG and IgM mediated)
what should you do if a transfusion reaction occurs?
stop the transfusion and manage specific signs
check the patient and product for evidence of haemolysis
what should you do if you have a patient with a transfusion reaction and signs of distributive shock?
fluid resuscitation
what should you do if you have a patient with a transfusion reaction and suspect hypersensitivity?
give anit-histemines
what should you do if you have a patient with a transfusion reaction and suspect bacterial contamination?
send sample for micro-biology and treat with broad spectrum IV antibiotics
what should you do if you have a patient with a transfusion reaction and dyspnoea?
provide oxygen
what should you do if you have a patient with a transfusion reaction and intravascular haemolysis?
monitor renal function and support
what should you do if you have a patient with a transfusion reaction and signs of volume overload?
slow infusion rate
give diuretic therapy
