Page 2023 - Hematology_ Basic Principles and Practice ( PDFDrive )

1794 Part XI Transfusion Medicine

incompatible donor RBCs. Because this is not an autoantibody, the
Workup of an Acute Intravascular Hemolytic Transfusion Reaction
patient’s own RBCs are not involved in the reaction.
If an acute transfusion reaction occurs: Typically an acute extravascular hemolytic transfusion reaction
1. Stop blood component infusion immediately. requires no special therapeutic intervention if the volume of incom-
2. Maintain intravenous access with a suitable crystalloid or colloid patible blood transfused is relatively low. The patient characteristically
solution. recovers in a few days as the incompatible donor RBCs are cleared
3. Maintain an adequate airway. from the circulation. If the volume of incompatible blood transfused
4. Monitor/maintain blood pressure and heart rate. Monitor renal was high, hemolysis can quickly lead to a severe anemia. Communica-
status (blood urea nitrogen, creatinine, volume status). tion with the blood bank is key to identifying how many units of
5. Give a diuretic or institute fluid diuresis, or both. incompatible units were transfused.
7. Obtain blood and urine studies for the transfusion reaction Extravascular acute reactions may occur if the patient’s preexisting
workup.
8. Blood bank workup of suspected transfusion reaction: alloantibody was missed by the blood bank during the antibody
• Check paperwork and identification to ensure correct blood screening process, if a wrongly labeled sample was used, if the unit
component was transfused to the correct patient. of blood was labeled for the wrong patient, or if the unit was hung
• Observe plasma for hemoglobinemia. on the wrong patient.
• Perform direct antiglobulin test.
• Repeat compatibility testing (crossmatch).
• Repeat other serologic testing as needed (ABO, Rh). DELAYED HEMOLYTIC REACTIONS
• Analyze urine for hemoglobinuria.
9. Monitor coagulation status (prothrombin time, activated partial The pathogenesis of a delayed hemolytic transfusion reactions
thromboplastin time, fibrinogen).
10. Monitor for signs of hemolysis (lactate dehydrogenase, bilirubin- (DHTR) is similar to that described for acute hemolytic reactions.
total/direct, haptoglobin). However, in DHTRs, the patient develops hemolysis 3–10 days after
the transfusion as an anamnestic antibody response to a blood antigen
previously known to the patient’s immune system through transfu-
sion, pregnancy, or hematopoietic stem cell transplantation (HSCT).
the setting of sickle cell disease with transfusion, acute malarial infec- Delayed hemolytic reactions occur more slowly than acute reactions
tion, passenger lymphocyte syndrome, paroxysmal nocturnal hemo- and are less likely to present as a clinical emergency. Hemoglobinuria
globinuria, and select cases of autoimmune hemolytic anemia. Petz and hemoglobinemia can occur but are less pronounced than with
and colleagues proposed the term sickle cell hemolytic transfusion reac- an acute intravascular reaction. This is probably because of the
tion syndrome to describe the constellation of hemolysis, sickle cell gradual increase in antibody, as well as the fact that most DHTRs
pain crisis, reticulocytopenia, severe anemia, RBC transfusion leading are caused by antibodies not efficient at activating complement. The
to accelerated hemolysis, and lack of a clear serologic reason for need for intervention is much less likely than with an acute hemolytic
hemolysis. Hyperhemolysis is frequently fatal because transfusion transfusion reaction, but hematologic and renal monitoring are
exacerbates hemolysis and the primary treatment for severe anemia prudent.
(RBC transfusion) makes anemia worse. Recognition of this syn- DHTRs are the most common presentation of transfusion-
drome is therefore critical because treatment should shift from associated immune hemolysis. DHTRs often involve the Rh system.
transfusion to administering erythropoietin, glucocorticoids, and Patients present with a fever, a falling hematocrit, and the develop-
intravenous immunoglobulin (IVIg), which have been used success- ment of a positive DAT with an eluate demonstrating a new RBC
fully in case series. alloantibody. Because these reactions are typically mild in nature, they
are usually addressed with supportive care only. In patients with sickle
ACUTE EXTRAVASCULAR HEMOLYTIC TRANSFUSION cell disease, DHTRs can precipitate vasoocclusive crises, autoantibody
production, or hyperhemolysis. It is prudent to take a transfusion
REACTION history in people with sickle cell disease who present with new
complications.
In an extravascular hemolytic transfusion reaction, complement is One final note regarding the serologic evaluation of a transfusion
either not fixed at all or is fixed only to C3b. In either situation, reaction: posttransfusion testing may be complicated and difficult to
because of the nature of the antigen-antibody reaction, complement interpret because of the possibility of autoantibodies or the involve-
activation with fixation of the C5b-9 complex does not occur. This ment of medications. In such circumstances, referral to the pretrans-
presentation is commonly associated with Rh antibodies, but can be fusion specimen is often helpful. In cases of more complex evaluations,
seen with any number of non-ABO antigen-antibody complexes. The consultation with an expert serologist is recommended to detect and
presence of IgG bound to the RBCs or C3b fixation results in an identify new alloantibodies in the patient’s plasma, which may be
extravascular reaction because the antibody-coated cells are cleared responsible for a hemolytic transfusion reaction.
by IgG receptors in the spleen or C3b receptors in the liver. In these
circumstances, RBC lysis does not occur in the intravascular space.
Because of the lack of generation of C3a or C5a, an extravascular FEBRILE NONHEMOLYTIC TRANSFUSION REACTIONS
hemolytic transfusion reaction does not usually present as a clinical
emergency. It is characterized by a positive DAT caused by recipient A febrile nonhemolytic transfusion reaction (FNHTR) is suspected
RBC alloantibodies binding to the incompatible circulating donor when a transient temperature rise of 1°C to over 38°C or more occurs
RBCs. Moreover, an increase in indirect bilirubin, an increase in during or after transfusion and when no other cause for the fever can
3
LDH, a decrease in hematocrit, a decrease in haptoglobin, and an be identified. In addition to fever, FNHTRs are often associated with
increase in colorless urine urobilinogen can occur, but hemoglobin- rigors and chills. In fact, rigors and chills can also manifest without
uria and hemoglobinemia are rarely present. The patient typically a concomitant fever, an atypical or “afebrile” FNHTR. In these cases,
remains clinically stable. Renal failure, shock, and hemostatic abnor- temperature increases may be masked by antipyretic premedication.
malities, such as DIC, are rarely seen unless the amount of incompat- Evidence supports two mechanisms of FNHTR: antileukocyte
ible blood infused is excessive. However, patients often have a antibodies and a storage lesion of released cytokines. Cytotoxic or
low-grade fever. agglutinating antibodies having human leukocyte antigen (HLA)
When an extravascular hemolytic transfusion reaction is suspected, specificity, neutrophil specificity, or platelet specificity may be present
the diagnostic test of choice is a DAT with an eluate. The eluate is in the recipient’s plasma and react against antigens present on trans-
performed to identify the antibody coating the RBCs. The positive fused donor lymphocytes, granulocytes, or platelets. Conversely,
DAT result reflects the patient’s antibody (or antibodies) coating the donor plasma may contain the offending antibody that can react with