The Daily Sign-Out

AABB Audioconferences for November: Hemorrhage in OB patients and cold agglutinins

AABB will host two audioconferences next month of interest pathologists who manage blood transfusion services.  A Nov. 3 audioconference will look at hemorrhaging in obstetric patients and describe OB transfusion protocols. Presenters will list the common causes of OB patients' hemorrhages and discuss preventive measures for these occurrences as well as review special transfusion requirements for these patients. A Nov. 17 session will provide an overview of cold agglutinins, including resolving cold-reacting allo and auto antibody issues, as well as typical clinical issues associated with cold agglutinins.

(I am a member of AABB but otherwise I gain no material benefit for passing along this info to you.)

NHLBI to fund research into storage lesion in donated blood

This is a bit "old news" but worth relaying.  In late June, the National Heart, Lung and Blood Institute announced the funding of nine grants to explore the effect of storage time on donated blood.  This is timely given recent studies that suggest increased risk of adverse cardiovascular and other organ events in people who received blood transfusions in which the storage time was greater than two weeks.

Current FDA guidelines permit liquid RBCs to be stored for up to 42 days (longer if the blood is frozen)--but the average unit of RBCs is transfused after 16 days' storage.  We at my institution consider an outdated RBC product (which is thus wasted) to be an exceptional event and call for a "root cause analysis" when this occurs--which fortunately is extremely rare.  (Plateletpheresis products are a different story for different reasons.)  Blood banks and transfusion services are between Scylla and Charybdis here: there is a chronic shortage of donated blood in the U.S. so any shortening of acceptable storage life would further exacerbate that shortage BUT there is the critical imperative to provide safe blood.

THe storage lesion in banked blood refers to the metabolic changes that occur in the RBCs during storage as well as the effects of hemolysis and shortened RBC survival with storage.  This results in the formation of RBC microparticles, release of free hemoglobin, and loss of RBC enzymatic functions--which not results in an ineffective or suboptimal therapeutic effect of the transfusion but also can cause widespread systemic deleterious effects.

These will be the first research projects to systematically examine collection, preparation, and storage practices as they relate to the RBC storage lesion.

Prevalence of HHV-8 in U.S. blood donors is low

One less thing to worry less about regarding transfusion-transmitted infections.

 

Transfusion: Prevalence of human herpesvirus 8 in healthy blood donors is low.

The first systematic study of human herpesvirus 8 in U.S. blood donors found that the prevalence of detectable genomes of HHV-8, which causes Kaposi's sarcoma, is very low in healthy donors. According to the study, featured in the May issue of Transfusion, a sensitive and quantitative real-time polymerase chain reaction assay was used to detect HHV-8 DNA from purified CD19+ B lymphocytes from 962 randomly selected U.S. whole-blood donors.

Read the abstract and editorial.

Pathologist Consults for Transfusion Issues

Over the years, I have developed a list of situations for a hospital transfusion service for which I (or the on-call pathologist) should be notified and consult with the med tech in the "blood bank."  Some of them are indeed mandatory but all of them generally are what I would described as deviations from the normal SOP.  I use my judgment on whether or not to directly call clinicians, the O.R., or go up to the floor--but when I have done any of the aforementioned, my input and advice has always been well-received.  Most of these are not emergency situations and encourage the techs to call us when it is practical even if it is in the middle of the night.  From a practical standpoint, I have learned that communication the next morning or day is by someone who was not actually involved in the situation and is handing off a scribbled note or incomplete verbal communication.  We (as pathologists) shouldn't underestimate our impact into patient care in unusual transfusion situations.

• Request for emergency release of uncrossmatched RBCs.  Although the blood needs to be out the door before I am reached, I want to know about this as soon as possible so I can speak to the clinicians and give them some reassurance and timeframes as more appropriate units are available (ABO- and then crossmatch-compatible).
• Adverse reactions to transfusion.  This is one of those mandatory situations and one in which we always issue a written report or note.  Also includes suspected transfusion-related acute lung injury (TRALI) and transfusion-transmitted infections (e.g., "look-back" and subsequent donor testing).
• High utilization of blood components.  This is the massive transfusion situation.  The anesthesiologists are fairly well-aware of the physiological sequelae of massive transfusion, so I mainly call them to get an idea of how the patient is doing so I can communicate to the blood bank on how many more units may be needed, our inventory, switching blood types, and whether or not an emergency run is needed to replenish our supply.
• Requests for specialized blood components.  This incorporates requests for washed RBCs, CMV-seronegative components, etc.  It is amazing how often such requests are made "because that is what we did in residency."  Most of these are not necessary and it provides me a "teaching moment."
• Feto-maternal hemorrhage.  The blood bank techs interpret the Kleihauer-Betke stain for the purpose of determining the appropriate dose of RhoGam and are not comfortable doing this.  We score adequately on proficiency testing but I think it touches the patient too much for them.  Anyway, I just like to know about these situations.
• Serological problems.  This includes positive DATs, newly discovered alloantibodies and autoantibodies, ABO discrepancies, etc.  This constitutes most of the day-to-day consults and mostly consists of reviewing the work-up.  I also approve send-outs to the Red Cross for additional work-ups and sign-off on the reports as they come back.  I just like knowing about these too and occasionally talking to clinicians if the work-up is delaying a patient receiving blood.
• Possibly inappropriate utilization of blood components.  This may be an emerging area for consultation but will likely be at a higher order level rather than at the direct patient care level.  Techs don't like functioning as gatekeepers and telling surgeons "no" so I encourage them to call me if something doesn't smell or sound right.

Hope you find this of help.  Your comments and questions are welcome.  Are there situations that you confront where a pathologist consultation is helpful?

Florida blood organization targets more donations from black community

from AABB Smart Briefs

The Blood Alliance in Jacksonville, Fla., has initiated a campaign that aims to increase the number of blood donations from members of the black community in order to meet the blood requirements of those with rare blood types and blood disorders, such as sickle cell disease. "In February, our focus was on African-American churches, and now we hope to challenge businesses with an African-American staff base," an official of the blood bank said.

This is a welcomed initiative to meet the challenge of providing compatible RBC products to not only sickle cell patients, who frequently develop multiple alloantibodies, but to other black patients who need antigen-negative blood for blood groups other than ABO/Rh.  Despite intensive research efforts for a blood substitute, a more practical and immediate approach is to increase donations from non-whites to address the differences observed in blood group antigen expression between different ethnic/racial groups.  It will be interesting to see how successful this initiative is or why it is different from other similar initiatives in the past.  Will track and follow-up.

FDA reports fatalities related to transfusion and blood collection for 2009

The FDA has released the summary for 2009 of transfused-related fatalities.  Of 74 transfusion-recipient fatality reports, they determined that 44 of the fatalities were transfusion-related, 22 of the fatalities were cases in which transfusion could not be ruled out as the cause of the fatality, and 8 of the fatalities were unrelated to the transfusion.

Interestingly, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO) accounted for the highest numbers of reported fatalities, followed by non-ABO hemolytic transfusion reactions. 

Another finding of note is that there were no reports of fatal microbial infections associated with RBCs, compared to 5 reports in FY2008, which were all due to Babesia infections.

A pdf of the report can be downloaded at the link above.

Dose of platelets in prophylactic transfusions for severe thrombocytopenia

Slichter and colleagues published a multi-institutional randomized trial in the February 18 issue of New England Journal of Medicine (article abstract) that evaluates the effect of platelet dose on various transfusion and clinical outcomes in patients receiving prophylactic transfusions for severe hypoproliferative thrombocytopenia.

The study included 1272 hospitalized patients who underwent allogeneic or autologous hematopoietic stem cell transplant (HSCT) or chemotherapy for hematologic or solid malignancies who were expected to have platelet counts of 10,000/mm3 or less for 5 or more days and received at least 1 plt transfusion--and excluded patients with active bleeding grade 2 or higher and those refractory to platelet transfusions (amongst other things).  Patients were randomly assigned to received platelet transfusions of low-dose (1.1x10e11), medium-dose (2.2x10e11)(=standard adult dose), and high-dose (4.4x10e11).  The primary end point was grade 2 or higher bleeding (according to the WHO bleeding scale).

Take-it-home: There was no significant difference in rates of grade 2 or higher bleeding or of other adverse events.

A couple more significant points:

• There were significant differences in the mean number of platelet transfusions between the low vs. medium and low vs. high groups.
• While there were significant differences in the median post-transfusion platelet counts and median increase in platelet count after transfusion between the low vs. medium and low vs. high groups, there was no difference between groups in the median 4-hr corrected count increment.
• While the platelet dose had no significant effect on bleeding, the percentage of patients with bleeding of grade 2 or higher was significantly higher in autoHSCT (57%) vs. chemotherapy (73%) and alloHSCT (79%) patients.

This is a significant study that has the potential to change practice, especially because of the acute shortage of plateletpheresis products.  Unfortunately, this study does not address one of the most difficult problems in these patient groups--platelet refractoriness.  It would be valuable to have a study that showed that low dose platelets transfused to platelet refractory patients weren't any worse or associated with more adverse events than standard dose platelets.