Interestingly , both studies found an association between older units and an increased risk of progressive coagulopathies . Maglaras et al . ( 2017 ) theorised that this may be due to increased levels of free-circulating haemoglobin within the unit during storage , which can lead to an increased risk of thrombosis and vasculitis , both of which can cause consumption of coagulation factors ( Garcia & South-Bodiford , 2012 ). This is yet to be determined but warrants further investigation as thrombotic disease could have damaging effects on a patient ' s outcome . Both studies also found a link between larger volumes of transfused PRBCs and an increased risk of multiple organ dysfunction syndrome ( MODS ), along with an increased transfusion reaction risk . Maglaras et al . ( 2017 ) questioned whether a more conservative transfusion strategy should be implemented to decrease these risks , but it should be queried why these patients are receiving larger units . It may be that patients requiring larger transfusion volumes are more at risk of developing conditions such as MODS due to their underlying conditions . This will , undoubtedly , increase the risk of a transfusion reaction due to the high numbers of circulating inflammatory factors already present ( Playfair & Bancroft , 2013 ).
Further research is required to determine new methods of storing PRBC units and reducing SL . In the interim , RVNs should be aware of the changes that could occur in PRBC units while in storage and ensure that any effects of SL are promptly noticed and treated to improve the outcome for their patient . In some cases , RVNs may still question whether , ethically , PRBC products that have undergone substantial metabolic changes should be transfused to patients that are already physiologically compromised .
Recommendations for further study
It is clear from the research reviewed that further research into transfusion medicine is warranted to further protect patients from fatal transfusion reactions . There is a risk of bacterial-contamination of PRBC units , which can induce sepsis , even if an aseptic technique has been performed ( Miglio et al ., 2016 ; Stefanetti et al ., 2016 ), so further research is required to evaluate the safest level of bacteria that can be administered in a transfusion without inducing a transfusion reaction .
In addition , to optimise patient safety , consideration should be given to updating guidelines on monitoring blood units while in storage . It is clear from the aforementioned studies that the regularly documented gross colour changes observed with bacterial contamination are not see as often as originally presumed , and perhaps bacteria causing colour changes differ depending upon the type of blood product stored ( e . g . whole blood vs PRBC ). It is also possible that the current recommended storage period increases the risk of bacterial contamination , as bacteria are given more time to reproduce . The 42-day storage period also provides more time for further biochemical changes to occur . However , shortening storage times could lead to veterinary practices reducing their stock levels and blood banks shortening expiration dates on their products , which could lead to excessive wastage and stock shortages . Current literature on the effects of storage length , SL and their involvement in blood transfusion reactions are all retrospective studies , so original clinical studies are needed to assess the true relationship between these variables .
The newly discovered Dal antigen and its dominant genetic aspect and geographical significance within North America warrants additional studies in other geographical areas , including the UK and other parts of Europe , to determine the prevalence of the Dal antigen in these areas . In addition , further studies into the clinical significance of Dal , Kai 1 and Kai 2 antibodies and their effect on provoking a transfusion reaction are warranted .
Recommendations for veterinary practice
Emerging research demonstrates that correct storage and monitoring of PRBCs is key to reducing the risk of a transfusion reaction . Therefore , veterinary practices that store blood products should ensure the daily implementation of protocols for the monitoring of storage temperature and duration , and the visual checking of products . The correct use of personal protective equipment ( PPE ) should be included in these guidelines to minimise the risk of bacterial contamination .
Due to advancements within transfusion medicine , it is not unheard of for a patient to have a transfusion history . However , with new RBC antigens being discovered , a patient ' s risk of reaction to subsequent blood transfusions increases , and current in-house blood-typing kits may not be enough to reduce the risk . Practices should therefore update their protocols to make cross-matching mandatory for all subsequent PRBC transfusions and familiarise themselves with how to carry out this procedure .
There are gaps in research into the clinical significance of the development of antibodies due to sensitisation to an unknown antigen and their role in eliciting a transfusion reaction . On completion of studies in this area , blood banks may have to revise their protocols for testing the blood antigen status of blood donors , to ensure all blood groups are accommodated . Due to the possibility of a breed predisposition among the newly discovered RBC antigens , a shortage of donors testing negative for either Dal , Kai 1 or Kai 2 may occur . There could be a reliance on littermates and family members to donate blood , as research suggests a strong dominant gene inheritance for these antigens . It may become difficult for veterinary practices to purchase safe , cross-matched units for their patients so they may need to create their own blood donor register , listing donors by antigen status to ensure safe transfusions .
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