Transfusion Flashcards
Prevalence of feline blood types in Aust/NZ`
A - 73%
100% Siamese, 8% Brit SH
B - ~20%
30% of DSH; 62% Brit SH; 54% Devon Rex
AB - <1% 1.4% of Devon Rex
Breeds with Dal negativity
Doberman 42%; Dalmatian 11%
Evidence for cross matching in dogs
JVECCS consensus - low LoE for naive patients but strong recommendation if transfusion in last 4d as multiple studies have demonstrated development of alloantibodies to DEA 3,5,7 and Dal
POC XM tests had poor sensitivity compared to lab based methods in a recent study
Cage side agglutination test for DAl antibodies had sensitivity of 87%; specificity of 96-100%
Impaired by severe anaemia
Evidence for cross matching in cat transfusion
Obviously strong LoE for type matching due to risk of acute haemolysis in B cats given A blood from alloantibodies to A antigen (but also anti-B in some A cats)
XM recommended by JVECCS consensus even in naive cats due to Mik antigen and reported prevalence of 7-15% of XM incompatible type matched cases
Conflicting reports on the significance of XM incompatibility - a large retrospective study (300 cats) suggested increased transfusion reactions in non-XM cats. While a small but prospective randomised study showed no difference in reaction rate or survival
Transfusion reaction Types
Febrile Non-haemolytic
Acute Respiratory - Transfusion associated dyspnoea, TACO, TRALI
Allergic type I hypersensitivity
Haemolytic - acute from mismatch immunogenic reaction. Non-immunologic from chemical/mechanical/osmotic or thermal RBC damage
Delayed serologic reaction (non-haemolytic)
Transfusion transmitted infection
Citrate toxicity/ hypocalcaemia
Hyperammonemia
Hypotenisve
Purpura
Why is parenteral iron supplementation preferred over oral
more reliable absorption,especially if iron deficiency is secondary to malabsorption
And has less associated GI side effects.
Oral Fe also reduces absorption of some medications including antibiotics
Transfusion products for coagulopathy - what each contain
Platelet concentrate, lyophilised platelets, PRP - mostly platelets, some RBC contaminants. Short shelf life, constant agitation. Used for thrombocytopaenia
Fresh Plasma - coag factors, Ig, protein.
Indicated for disorders of 2ry haemostasis including rodenticide, vWD, Haemophilia A and B. Not indicated for hypoalbumin as volume needed would be 1x plasma volume to raise
FFP - stores 1 yr
Cryoprecipitate - concentrated vWb, fibrinogen, F5 and 8
Good for vWD and Haemophilia A (not B)
What changed opinions on HES
the concept of colloid therapy was strongly based on the Starling concept, which was discovered more than 100 years ago. Many of these expectations are invalid, due to recent findings in the area of microcirculation and endothelial glycocalyx layer (e.g., ‘revised Starling’ model). In particular, there is no reabsorption from the interstitial space into the intravascular space (‘no absorption rule’).
However, in humans they can use albumin or other readil available blood products and
In veterinary medicine, HES cannot be easily replaced by albumin or plasma as the safety profile for human serum albumin solutions is worse compared with HES,12-14 and allogenic plasma or albumin products are not ubiquitously available and are more expensive
Evidence AGAINST the use of HES
- May not achieve higher volume expansion than crystalloids - and dependent on the integrity of the glycocalyx (so in conditions like sepsis they may not be superior to crystalloids)
- May adsorb to glycocalyx and restrict ultrafiltration
- May be assoc with AKI in humans (osmotic nephrosis and other mechanisms)
–> study in dogs reported increased NGAL in urine of those getting HES suggestive of tubular damage. another retrospective study reported higher incidence of AKI and non-survival in HES treated dogs - Phagocytosed intracellular HES can persist for up to 18 days in canine kidneys, depending on the dose received
- Assoc with impaired coagulation in humans (inactivation of vWF and FVIII, binding plt surface receptors, accelerated fibrin degradation)
A study in dogs after experimentally induced haemorrhage showed a transient hypocoagulable state consistent with dilution. But still caution if already underlying coagulopathy - Risk of fluid overload which may increase risk of mortality
- Dogs recieving HES in retrospective studies have a higher mortality rate but this is confounded by retrospective nature and these being potentially sicker dogs,
Positives of HES
In dogs with experimental haemorrhagic shock, endothelial glycocalyx shedding, and inflammation were found to be significantly less after tetrastarch compared with the 4-fold volume of isotonic crystalloid
In normovolaemic, healthy dogs, hetastarch led to the highest volume expanding efficiency after 30 minutes (blood volume increase by 140%) compared with hypertonic saline and normal saline, which lasted up to 4 hours.
recent data suggest that tetrastarch may not cause AKI, as measured by several renal biomarkers for AKI and renal histology, when used for volume resuscitation in experimental haemorrhagic shock in healthy non-septic dogs
In dogs with normal clotting function HES did not impair coagulation beyond the expected dilutional effects.
What is the glycocalyx
Membrane bound polysulphated proteoglycans, HA, glycoproteins and plasma proteins on endothelial surface, shielding it from blood flow.
Regulate vascular permeability
The reason why oncotic pressure is not as important on regulation of intravascular fluid homeostasis
If damaged will increase vascular permeability –> fluid movement out of intravascular space
