Transfusion Flashcards
Maximum allowable blood loss equation
MABL= EBV x [(hct initial- hct acceptable)/hct average]
What is Hetastarch?
- Hetastarch is a synthetic colloid solution
- Reported to decrease factor VIII:C levels and interfere with clot formation
- Recommended dosage <20ml/kg
What factors does cyroprecipitate contain?
- Fibrinogen, vWF, VIII, XIII
- 1 unit has 80-145 U factor VIII and 250mg fibrinogen
- 1 unit = 10mL
Coagulation factors including FFP and platelets should be administered after how many PRBCs?
FFP after 12. Platelets after 20.
What factors decrease after massive transfusion?
Factors 5 and Fibrinogen the most. Factor 8 as well (but less bc released from endothelium during surgical stress)
What is the incompatibility risk of fully crossmatched blood?
0.05%
Most common blood group and RH status?
O blood in 45% white and 50% blacks. 85% of humans are Rh positive.
Relative contraindications to autologous blood donation?
HOCM, severe AI, anemia, recent MI, severe left main disease
What is a normal extraction ratio while
resting?
25% in a healthy adult. May increase to 80% during max exercise in athletes.
Why does the curve right shift in anemia?
Increased 2,3 DPG is made by the tissue to facilitate unloading of oxygen.
What does cryoprecipitate contain?
250mg Fibrinogen, VWB, Factor 8, Factor 13, and fibronectin.
What does FFP contain?
Fibrinogen, all procoagulants and fibronectin. But much less per unit volume than cryo!
How much will one unit of platelets increase platelet count?
5,000- 8,000
Hct of packed reds?
70-80%
HIV risk from transfusion? Hep B risk? Hep C risk?
HIV: 1 in 2,000,000. The window is now 10 days.
Hep C: 1 in 1,900,000
Hep B: 1: 200,000
How is a type and screen done?
Pt’s RBC are tested with serum known to have antibodies to A & B. Confirmed by testing pt’s serum against RBC’s with known antigen. Antibody screen is done by mixing pt’s serum with known antigenic compositions (indirect coombs test and takes 45 mins).
How is a type and crossmatch done?
Mix donor RBC with recipient serum.
What is the incidence of a serious hemolytic rxn with a negative antibody screen (without crossmatch)?
~1: 10,000 or 0.06% (depending of what you read)
What is the benefit of a crossmatch?
Assures optimal safety, detects less common antibodies, confirms ABO Rh and detects low titer antibodies.
What is donated blood tested for?
Hep B, Hep C, Syphilis, HIV, West nile virus, Chagas, HTLV
How long can blood be stored in CPDA-1?
~35 days (C=citrate, P=phosphate, D=dextrose, A=adenosine)
How long can platelets be stored and at what temperature?
5 days at 20-24 degrees celsius.
What are the most labile clotting factors in plasma?
V and VIII
How long do transfused platelets survive?
1-7 days
Each unit of FFP will increase clotting factors by how much?
2-3%
How long can FFP be stored and at what temp?
1 year at -18 degrees celsius
Anaphylactic rxn to blood are usually due to?
IgA deficiency. Occurs at a rate of 1: 150,000
What are the complications of massive transfusion?
Coagulopathy (dilutional thrombocytopenia), citrate toxicity, hypothermia, acid base balance (citrate and lactic acid metabolized to bicarb in normal liver), serum potassium
What is the physiologic compensation for isovolemic hemodilution/chronic anemia?
Increase CO secondary to increase in SV (decrease SVR and decrease viscosity), improved microcirculation, increase tissue extraction (increase 2,3 DPG and shift curve to the right).
