Category: Patient

Includes compatibility testing (AHG, electronic, immediate-spin), antigen typing, antibody screening and identification, direct antiglobulin testing, elution, transfusion reaction and drug reaction workups, component typing tests upon receipt in hospital blood bank, release and return of components

How I Select Technologist Candidates for Work or Promotion

drzeyd

As a transfusion medicine physician, I must know if I can trust my staff’s interpretation of immunohematology testing.  I may be called at night and they will provide me with results and I must use these to make a medical judgment.  If their interpretation is flawed, I might make a decision that harms the patient.

I really don’t like multiple-choice questions, but nowadays this is often the norm.  For my staff, especially senior staff and those who want to be promoted to senior staff, I have developed a series of projective exercises to help me understand their thought processes. I also used this approach on prospective candidates for hire.

Here is a sample exercise.  I have the candidate or staff review this panel and tell me to interpret it:

Most of them answer that this is an anti-Cw without hesitation.  However, they are basing that on only one Cw-positive cell.

More astute ones indicate it might be anti-Cw but ask to test additional Cw-positive cells and perform an enzyme panel.  These are the ones that I will consider for hire or promotion now.

Product Delivery in Medinfo 1

drzeyd

This is the start of a series of posts on how Medinfo blood bank software was designed for product delivery in the HMC system in Doha.

The overall process was:

  1. Transfer blood components (all types) from the Blood Donor using the Interdepot Transfer process (see that post for details) to the Hamad General Hospital HGH General Delivery Deposit.
  2. Release components to individual HMC system hospitals and client blood banks from the HGH General Delivery Deposit,.

It was also possible to release blood components directly from the Blood Donor Center to HMC hospital blood banks as a contingency.  Client hospitals outside the HMC system still had to obtain their components from HGH General Delivery Deposit.

Antiglobulin Reagents

drzeyd

Antiglobulin reagents are used to detect molecules bound to the RBC surface.  What they detect depends on their specificity.  Such detection can be performed in the routine immunohematology laboratory or elsewhere such as flow cytometry.  This discussion is for the blood bank laboratories, both routine and reference immunohematology.

This is how I classify and use the various reagents in my daily practice:

  • Routine use—DAT testing and compatibility testing
  • Antibody identification
  • Drug-related hemolysis and transfusion reaction workups
  • Special assays:  DAT-negative AIHA, prediction of clinical significance of reaction by IgG subclass determination

There are many types of antiglobulin reagents:

  • Polyspecific:  IgG and complement usually C3d but sometimes C3b specificity included
  • Whole Molecule IgG including mu heavy chains and kappa and lambda light chains
  • Monospecific gamma heavy chain, mu heavy chain, alpha heavy chain, C3c, C3d, C3b
  • IgG subclass:  IgG1 IgG3

Whole molecule IgG detects class-specific mu heavy chains AND light chains kappa and lambda.  Since kappa and lambda are found on all immunoglobulin classes, whole molecule reagents can detect IgM so there may be weak staining with cold antibodies that are not clinically significant.

C3d is the final breakdown product of C3b and does not cause hemolysis.  Its presence merely means that at some time—unspecified—complement was fixed.  C3c is an intermediate product in the breakdown pathway.  If detected, C3c positivity means ACTIVE complement fixation was occurring at the time of specimen collection.

General Use:

Routine DAT testing:

  • Polyspecific:  if positive, then use
  • Monospecific IgG and monospecific C3 reagents

Antibody workups:

Routine:  antibody screens and AHG crossmatch (if indicated)

  • Polyspecific
  • Gamma heavy-chain monospecific

Monospecific gamma heavy chain is preferred to minimize non-clinically significant, cold antibody interference.

Complicated—where detection of complement reactivity is especially important:

Polyspecific for drug-related hemolysis and transfusion reactions

Difficult antibody workups, e.g. to rule out anti-Jka and/or anti-Jkb

Specialty Reference Procedures:

  • DAT-negative AIHA:  mu heavy chain, alpha heavy chain for IgM and IgA mediated hemolysis (rare), C3c to detect active complement fixation
  • Predicting clinical significance:  IgG1 IgG3

Complement fixation may be important in various drug-related hemolysis and some transfusion reactions so I always use a polyspecific reagent in these situations.  Most antibodies can be detected by gamma heavy-chain specific reagents;  however, there are rare examples of anti-Jka and anti-Jkb which are only detected by complement.  Whenever I have a nonspecific reaction in an Jka-negative or Jkb-negative patient, I repeat the AHG panel using polyspecific reagents.  I do not use polyspecific routinely because of the nonspecific and non-clinically significant cold antibodies.

One way to assess for the clinical significance of an antibody is to determine its IgG subclass.  In general, IgG3 antibodies may fix complement and cause severe hemolysis.  Both IgG1 and IgG3 antibodies cross the placenta and may cause hemolytic disease of the fetus/newborn.

In summary, when reviewing immunohematologic reactions using AHG, I always remember to check which type of AHG reagent was used.  I always keep multiple types of AHG reagents in the laboratory for the reasons explained above.

TRALI TACO

drzeyd

This is a revision of a previous post, incorporating an updated definition of Transfusion-Associated Cardiac Overload TACO from the National Healthcare Safety Network, Biovigilance Component Hemovigilance Module Surveillance Protocol,  Version 2.6.

Case Study: Importance of Enzyme Panels in RBC Antibody Workups

drzeyd

I am a strong believer in performing both AHG and enzyme panels together in routine antibody workups.  I especially feel this is important when the patient is R1R1 since I always want to rule out anti-c.  Sometimes, anti-c is only identified in the enzyme phase.

This is a case from my files of an R1R1 patient with the following results:

Antibody Screen:

AHG Panel:

Enzyme Panel (Ficin):

This anti-S is enzyme-labile but anti-c is revealed, only reacting at enzyme phase.  The patient was Kell-negative so I selected S-negative, R1R1 K-negative RBCs for transfusion.  Anti-c can be a dangerous antibody causing severe hemolytic disease of the fetus/newborn and sever hemolytic transfusion reaction.  If only the AHG panel had been performed, the anti-c would have been missed.

Hypotonic Saline to Phenotype Multiply Transfused Sickle Cell Patient

drzeyd

Nowadays, if we have a multiply transfused patient with a complex antibody pattern, we might resort to RBC genotyping to help us resolve the antibody issues.  Fortunately, there is one situation where we can quickly phenotype the patient by using hypotonic saline to lyse the transfused RBCs since the sickle cells are resistant.

The results can be quite clean and easy to interpret as in the following example using 0.4% saline:

It is a lot cheaper to make dilute saline than an RBC genotype—and much quicker!

Management of Acute Transfusion Reactions

drzeyd

This was a teaching document for medical students and residents I made for NGHA Riyadh. I have updated it for leukodepleted components and platelet additive solution.

Immediate Steps for All Reactions:

  1. Stop Transfusion.
  2. Keep IV Open with 0.9% NaCl.
  3. Verify correct unit was given to correct patient.
  4. Notify attending physician and blood bank

After Transfusion is Terminated (except mild allergic, see below):

  1. Send report of reaction, freshly collected blood, and urine samples with blood unit and administration set to blood bank.
Reaction TypeSigns and SymptomsEtiologyClinical Action
Allergic (mild)Pruritus, urticaria (hives)Antibodies to plasma proteinsSteps 1-3 above; administer antihistamines (PO, IM, or IV); resume transfusion if improved; if no improvement in 30 minutes treat as below.
Allergic (moderate to severe)Hives, dyspnea, abdominal pain, hypotension, nausea, anaphylaxisAntibodies to plasma proteins, including IgA (patient has anti-IgA antibodies)Steps 1-5 above; administer antihistamines, epinephrine, vasopressors, and corticosteroids as needed; avoid future reactions by premedication and consider use of washed red cells if refractory.
Febrile (mild to moderate)Fever, chills, rigors, anxiety, mild dyspneaAntibodies to leukocyte antigens, (mostly HLA): cytokinesSteps 1-5 above; mild—administer antipyretics as needed; avoid future reactions by premedication and use of leukodepleted red cells and platelets
Acute lung injuryFever, chills, dyspnea, respiratory failureAntibodies form donor plasma to recipient WBCs; less commonly recipient antibodies to donor WBCsSupportive therapy for respiratory failure, oxygen, mechanical ventilation, leukodepleted blood components, consider use of solvent detergent plasma, minimize plasma transfusions (use platelets in additive solution and leukodepleted RBCs in additive solution).
Acute hemolyticAnxiety, chest pain, flank pain, dyspnea, chills, fever, shock, unexplained bleeding, hemoglobinemia/ hemoglobinuria, cardiac arrestHemolytic transfusion reaction; usually due to ABO incompatibilitySteps 1-5 above; treat shock with vasopressors, IV fluids, corticosteroids as needed; maintain airway; increase renal blood flow (IV fluids; furosemide); maintain a brisk diuresis; monitor renal status for acute renal failure. Monitor coagulation status for DIC; administer blood components as needed after etiology is clear.
Septic / toxicChills, fever, hypotensionBacteria in contaminated bloodSteps 1-5 above; treat shock with vasopressors, IV fluids, culture patient and blood bag,antibiotics.