Info
🌱 來自: Huppert’s Notes
Transfusion Medicine🚧 施工中
Transfusion Medicine
Standard testing
• ABO typing: Determine A/B antigens present on RBCs (blood type A, B, AB, or O)
• Rh(D) typing: Tests for D antigen on RBCs (e.g., A+ vs. A–)
• Type and screen: Tests for unexpected antibodies in patient plasma that might react with transfused product and cause hemolysis. Must be done q72 hrs.
• Type and cross: Final confirmation test that is performed by mixing the patient’s plasma and the donor’s RBCs. Performed when transfusion is imminent/very likely.
Antibody testing
• Direct antiglobulin test (DAT or Coombs): Tests for auto-antibodies on the patient’s RBCs
- Mix patient’s RBCs + Coomb’s reagent (anti-IgG, anti-C3)
• Indirect Coombs: Tests for antibodies in the patient’s plasma
- Mix patient’s plasma + donor RBCs and Coomb’s reagent
Apheresis (separation of blood)
• Plasmapheresis: Removes high molecular weight proteins from plasma (i.e., antibodies). Used in TTP, hyperviscosity syndrome, cryoglobulinemia, myasthenia gravis, Guillain-Barré syndrome, anti-GBM, some ANCA vasculidities.
• Cytapheresis: Removes cellular components (i.e., leukapheresis: removes WBCs in acute leukemia)
Complications of transfusion
• Hypocalcemia: Citrate used to preserve pRBCs chelates calcium
• Volume overload: Blood products stay mostly intravascular, so 250 cc of pRBCs (1 unit) is equivalent to 1000 cc normal saline. Rapid increase in intravascular volume can lead to circulatory overload and increased hydrostatic pressure, which can worsen active bleeding.
Special preparations of blood
• Leukoreduced: WBCs filtered out
- Decreased risk of febrile reaction in patients with prior febrile non-hemolytic transfusion reactions
- Deceased risk of HLA/RBC alloimmunization in patients who are chronically transfused (i.e., patients with hematologic malignancies, transplant candidates)
• CMV reduced-risk: Requires CMV-negative donor or leukocyte reduction to remove mononuclear cells; prevents CMV transmission in CMV-negative recipients of bone/organ transplant, pregnant women, HIV+ patients
• Irradiated: Prevents donor T-cells from attacking host marrow
- Used to prevent TA-GVHD in 1st degree–related donors for heme malignancy, bone marrow transplant (not solid tumor transplant or HIV+)
• Washed: Removes anti-IgA antibodies and plasma proteins
- Prevents anaphylaxis in severe IgA deficiency
Types of blood products
• Packed red blood cells (pRBCs): 1 unit = 250cc, expect to increase Hgb by 1 g/dL
- Transfusion time: 60–240 min
- Transfusion goal: Depends on patient-specific factors
• Goal: Hgb >7 g/dL in most patients
• Goal: Hgb >8 g/dL in stable CAD and ACS
• Platelets: 1 pheresis (6-pk) = 300 cc, expect to increase platelet by 30K/µl
- Transfusion time: 30–60 min
- Pooled platelets = platelets removed from whole blood donation from many donors
- Apheresis = platelets from a single donor
- Transfusion goal: Depends on patient-specific factors
• Goal: Plt >10K/μl prophylaxis against spontaneous bleeding in most patients
• Goal: Plt >50K/μl if major bleed
• Fresh frozen plasma (FFP): 1U = 250 cc, contains all coagulation factors
- Transfusion time: 30–60 min
- Half-life <7 hrs
- INR of FFP is ~1.6 (cannot decrease INR less than this with FFP transfusion)
• Cryoprecipitate: 10U = 150 cc, contains fibrinogen, fibronectin, factor XIII, VIII, vWF
- Transfusion time: 30–60 min
- Indications: Bleeding, low fibrinogen (e.g., DIC, massive transfusion)
- Fibrinogen replacement: 0.2 bag/kg provides 100 mg/dL fibrinogen
• If fibrinogen 50–100 mg/dL, give 10 U
• If fibrinogen 0–50 mg/dL, give 20 U
- Half-life 3–5 days
• Coagulation factors:
- Plasma derived or recombinant factors VIII and IX (used in hemophilia)
- Recombinant factor VIIa (Novo-seven)
- Prothrombin Complex Concentrate (PCC, KCentra): 4-factor (contains factor II, VII, IX, X)
• Albumin: 5% (iso-oncotic) vs. 25% (hyper-oncotic)
- All bottles contain 12.5g albumin + 154 mEq Na+ (isotonic)
- Approved uses for albumin: cirrhosis + HRS, cirrhosis + SBP, cirrhosis after large volume paracentesis (≥4L fluid removed)
TABLE 7.5 • Transfusion Reactions: Clinical Presentations and Management
Transfusion reactions