ABO/D Blood Groups Understanding Critical For Safe Transfusions.
BLOOD GROUPS- A REVIEW Human erythrocytes >300 antigenic determinants Only ABO and Rh important in...
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Transcript of BLOOD GROUPS- A REVIEW Human erythrocytes >300 antigenic determinants Only ABO and Rh important in...
BLOOD GROUPS- A REVIEW
• Human erythrocytes >300 antigenic determinants
• Only ABO and Rh important in the majority of blood transfusions
• Most severe transfusion reactions due to ABO incompatibility
Alicia Gruber-Kalamas, MD, University of California San Francisco
ABO INCOMPATIBILITY
Intravascular HemolysisHemoglobinemiaHemoglobinuria
DEATH
DICProfuse Bleeding
Acute Circulatory CollapseAnuria
Donor blood antigen+
Recipient antibodies (IgM)Activates Complement
Alicia Gruber-Kalamas, MD, University of California San Francisco
THE Rh SYSTEM
- Rh gene 3 chromosomal loci with 6 alleles -D antigen is the most common and most immunogenic
-Approximately 80-85% Caucasians have D antigen
- Individuals lacking this allele are called “Rh-negative”
-Only develop antibodies against the D antigen after exposure (transfusion/pregnancy)
Rh ANTIBODIES
• IgG class of immunoglobulins
• Lack capacity to bind complement
• Elimination of red cells primarily in the spleen
• Clinical symptoms mild, generally limited to fever/chills
Rh AND THE PREGNANT WOMAN
• Transplacental passage of D-positive fetal RBC’s into D-negative mother produces anti-D (IgG)
• Anti-D IgG traverses the placenta and coats fetal RBC’S leading to extravascular hemolysis
• Clinically manifest as hemolytic disease of the fetus and newborn- anemia, hepatosplenomegaly, hydrops fetalis, and death
Rh PROPHYLAXIS- Rhlg
• 1968 RhIg first licensed for prophylactic administration via IM route (RhoGam)
• IgG anti-D derived from human plasma• Exact mechanism unknown• 20 mcg purified RhIG provides protection
against 1 ml Rh-positive blood• WinRho IV preparation
PREVENTION OF POST-TRANSFUSION Rh-ALLOIMMUNIZATION
The protective effect of RhIg is dose dependent
RhIg can prevent Rh immunization if:1) Sufficient dose is administered2) RhIg is given within 72 hours of exposure
Succesful Prevention of Post-Transfusion Rh
Alloimmunization by IV WinRho
Anderson, et al A. J. Hematology 1999; 60:245 Case Report
• 10 mo old D-negative female• Received 40 ml D-positive PRBC’s• Administered 1200mcg IV WinRho • At 1 year follow-up, no evidence of Anti-D
RBC Exchange with Rh-negative Cells: An Alternative Approach
Werch et al Transfusion 1993; 33:530
• 22 y/o Rh-negative woman received 10 units Rh-positive PRBC’s
• RBC exchange with Rh-negative cells 12 hours post-exposure in addition to RhIG
• 11 months later delivered healthy, Rh-negative child; no evidence of Anti-D
FOLLOW-UP• Blood Bank informed of the error
• Calculated dose was 27,000 IU WinRho
• 3000 IU IV Q8hrs x 9 doses ($$$$$$)
• Pt will require follow-up at 6 months to check for presence of anti-D antibodies
PROCEDURE AT SFGH
• Blood bank alerted to activation of “911”
• If pt male, 2U O-positive sent to ED; if pt female, 2U O-negative sent to ED
• 6U O-positive is kept in OR at all times
• O-negative must be sent from Blood Bank
IN SUMMARY
• Rh D Antigen is of huge clinical significance for young females and women of child-bearing age
• If a Rh-negative women inadvertently receives Rh-positive PRBC’s, whole blood, or platelets, the appropriate calculated dose of WinRho must be administered within 72 hours of exposure
WHAT IS CORRECT BLOOD TYPE?
Type O OK No No No
Type A OK OK No No
Type B OK No OK No
Type AB OK OK OK OK
FFP Type O Type A Type B Type AB
Blood to lab4 units PRBC (0+)in ED (0-) women
From blood sample:• CBC including platelets• PT, PTT• Fibrinogen
Crystalloids + re-evaluateIndication forimmediate transfusion
Give 2 units PRBC
Review labsCoagulopathy present?
Hct < 30 percent?
PT > transfusion threshold
Anticipated ongoing blood loss
De-activate massivetransfusion protocol
Crystalloids +blood by lab values
Give 4 units of FFP and6 packs of platelets
Give whole blood (preferred)or packed cells to HCT 30
Transfuse to maintain thresholds:• Hct < 30 percent• FFP with PC ratio of 1:1• Platelets with PC in ratio of 1:1
Indications for type O blood:• BP < 70 mm Hg• PT, PTT• get fibrinogen
Indications for transfusion protocol:• BP < 90 mmHg after 2 PRBC• Blood loss = circulating blood volume
Monitoring protocol:• Hct, PT, PTT, fibrinogen and platelets• Create flow sheet• EBV70-90 ml/kg
Transfusions thresholds• HCT, PT, PTT• INR > 2.0 usually• INR > eye, brain, airway, 1.7 bleeding• platelets < 75,000 usually• fibrinogen < 100 mg/dl
PC < transfusion threshold?
No
YesNo
YesYes
NoYes
No
No Give platelets, 6 packs toPC 25-50, 000
Yes
No
No
TABLE 47.5. An Algorithm for Massive Transfusion*
TABLE 47-6. CORRELATION BETWEEN PLATELET COUNT AND INCIDENCE OF BLEEDING
Platelet Count Total No. No. of Patients
> 100,000 21 0
75,000 - 100,000 14 3
50,000 - 75,000 11 7
< 50,000 5 5
(Cells/mm3) of Patients With Bleeding
Data from Miller et al58
A New Treatment For Transfusion Induced Coagulopathy
• Recombinant activated coagulation Factor VII (r FVIIa) (NovoNordisk)
• Rx coagulopathic intraoperatively
• Expensive
• Should be viewed as “rescue” therapy until FDA is more evident
LIMITATIONS OF BLOOD TRANSFUSIONS
• Transmission of infectious diseases
• Dependent on volunteer donors (shortage?)
• Need for typing and cross-matching
• Short shelf-life
RECOMBINANT HEMOGLOBIN (rHb)
A genetically engineered recombinant human hemoglobin which can be used as red blood cell substitute
OLD HISTORIC PROBLEMS
• Kidney failure
• Oxygen dissociation curve
WHAT ABOUT THE
OXYGEN AFFINITY?
ADVANTAGES OF rHb
• No risk of blood-borne infection
• No need to type and cross-match
• Optimized oxygen delivery
• No need for chemical modifications
• Improved shelf-life
• Economic scale-up, production, and supply
UPDATE SYNTHETIC BLOOD
Biopure produces a product named Hemopure. It is approved in South Africa and will be in the USA and Europe in a year.
Stealth Red Cell. Polyglycol covering preventing antibodies from getting to it, but still needs ABO testing. Will lengthen half-life by many days. (or 30 days.)
PREDICTION:
In 15 years, human blood will not be used as a blood transfusion (at least for the purpose of delivering oxygen.)