PHILIPPINE ASSOCIATION OF MEDICAL TECHNOLOGISTS - NEVADA, INC.
"To serve the community, the profession, and the person."
AUTOMATED TESTING FOR THE HOSPITAL TRANSFUSION SERVICE
by William Kopp, SBB (ASCP)
Staffing shortages due to the lack of qualified personnel in the job market and hospital cut backs are making blood bank automation interesting to a large number of hospitals who would have not previously looked at blood bank automation. With the number of experienced technologists leaving the field exceeding the expected number of graduates from medical technology schools, automation will become increasingly important to hospital blood banks. The initial high cost of automated equqipment for the blood bank and the cost of operating the systems can often be justified by the lack of experienced technologists who can consistently perform accurate manual tube tests.
Patient safety is also a consideration when a hospital blood banks evaluate the techniques they will be using. Automation allows a consistency in test accuracy and sample identification not attainable in manual testing. With older more experienced technologists leaving the field in significant numbers , increased safety due to positive sample identification and consistency in test performance is a significant consideration in the decision to continue with manual methods or to change to automated equipment.
Two systems for hospital transfusion service testing which are getting a significant amount of attention by laboratory managers are the Ortho TECAN MegaFlex system and the Immucor ABS 2000. The MegaFlex system uses gel technology while the ABS 2000 is a solid phase test system. Both systems are FDA licensed and available for use in hospital blood bans. In busier hospital blood banks these systems may result in as much as a 50% decrease in staff time for immunohematology testing. Both systems give good results when compared to the sensitivity of tube tests using either LISS additives or polyethylene glycol.
There are some unexpected benefits of automated blood bank testing. The amount of biohazardous waste is reduced when tubes are no longer in use. Another benefit to reduce staff time is that existing staff may be freed for other duties may help other sections of the laboratory
Hospitals considering blood bank automation need to consider costs, both initial and operating costs as compared to the cost of technologist time, reagents, and supplies for manual testing. It is also important to consider how the instrument will interface with existing computer systems and how will testing be done if the instrument is down. In situations where the staff is experienced with the automated system and not experienced with tube testing, instrument down time may be a serious issue. It is also important to consider how the instrument will process stats. Can a batch be interrupted to add stat tests and what will the turnaround be?
Paxton, A. Blood Banks Steo Up Move to Automation, CAP Today, October 1999.
Check, W. Order In The Blood Bank:Automation Step UP, CAP Today, October ,2002
California Blood Bank Society,e-Network Form, What Is The Status of Automated Pre-Transfusion Compatibility Testing, July 2001
ABO INCOMPATIBLE PLATELET TRANSFUSIONS
When giving platelets that are not ABO identical with the patient, there may be problems that are not always considered. ABO antibodies in the plasma transfused with the platelets may have an adverse affect on the patient’s red cells. The patient’s ABO antibodies may shorten the survival of the transfused platelets and ABO mismatched platelet transfusions may increase the rate patients become refractory to further platelet transfusions. All of these problems have the potential of being serious or life-threatening events. In some cases, the plasma from group O donors may cause hemolytic reactions when given to group A or B patients. Although rare, the possibility of a hemolytic reaction should be considered when giving group O platelets.
When ABO incompatible plasma is transfused, the donor’s ABO antibodies bind to the patient’s red blood cells. This may cause a positive direct Coombs test that may complicate the clinical picture and add increased costs for technologist’s time when elution studies become necessary.
Platelets have varying expression of the A and B antigen on their surface. However, a significant number of group A and B platelet donors have enough group A or B antigen on the platelet’s surface to cause significant reduction in the one hour, post transfusion recovery when given to a group O patient. Group A and B patients are less likely to have a significant reduction in platelet survival due to ABO antibodies because they do not produce anti-A, B.
A paper published by Carr, et. al,. in the BRITISH JOURNAL OF HEMATOLOGY, 1990;75, suggests that the transfusion of ABO incompatible platelets may increase the rate that patients become refractory to platelet therapy. There is also evidence that ABO incompatibility adds to the effect of HLA and platelet antigen specific antibodies causing faster destruction of the transfused platelets.
For a more detailed review of the problems associated with the transfusion of ABO incompatible platelets see, “ABO and Platelet Transfusion Therapy,” by L. Cooling, IMMUNOHEMATOLOGY, Volume 23, Nov., 2007. Cooling’s article and many other excellent articles are available on line at www.redcross.org/pubs/immuno/.
William Kopp,SBB (ASCP)
St Rose Hospital,Siena
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