Blood and Blood Products, Chapter19 P124-128 Flashcards
Define the following terms:
PT
P124
Prothrombin Time: Tests extrinsic coagulation pathway
Define the following terms:
PTT
P124
Partial Thromboplastin Time: Tests intrinsic coagulation pathway
Define the following terms:
INR
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International Normalized Ratio (reports PT results)
Define the following terms:
Packed red blood cells (PRBCs)
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One unit equals 300 ml (50 ml); no platelets or clotting factors; can be mixed with NS to infuse faster
Define the following terms:
Platelets
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Replace platelets with units of platelets
6–10 units from single donor or random donors
Define the following terms:
Fresh frozen plasma (FFP)
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Replaces clotting factors; (no RBCs/WBCs/platelets)
Define the following terms:
Cryoprecipitate (cryo)
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Replaces fibrinogen, von Willebrand factor, and some clotting factors
Which electrolyte is most likely to fall with the infusion of stored blood? Why?
P124
Ionized calcium; the citrate preservative used for the storage of blood binds serum calcium
What changes occur in the storage of PRBCs?
P124
↓Ca, ↑ K, ↓2,3-DPG, ↑ H (↓ pH),
↓PMNs
What are general guidelines for blood transfusion?
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Acute blood loss, Hgb < 7
What is the rough formula for converting Hgb to Hct?
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Hgb x 3 = Hct
One unit of PRBC increases Hct by how much?
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≈3% to 4%
Which blood type is the “universal” donor for PRBCs?
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O negative
Which blood type is the “universal” donor for FFP?
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AB
What is a type and screen?
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Patient’s blood type is determined and the blood is screened for antibodies; a type and cross from that sample can then be ordered if needed later
What is a type and cross?
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Patient’s blood is sent to the blood bank and cross-matched for specific donor units for possible blood transfusion
Define thrombocytopenia.
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Low platelet count (<100,000)
What are the common causes of thrombocytopenia
in the surgical patient?
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Sepsis, H(2) blockers, heparin, massive transfusion, DIC, antibiotics, spurious lab value, Swann-Ganz catheter
What can be given to help correct platelet dysfunction
from uremia, aspirin, or bypass?
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DDAVP (desmopressin)
What common medication causes platelets to
irreversibly malfunction?
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Aspirin (inhibits cyclooxygenase)
What is Plavix®?
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Clopidogrel—irreversibly inhibits platelet
P2Y(12) ADP receptor (blocks fibrin
crosslinking of platelets)
What platelet count is associated with spontaneous bleeding?
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<20,000
What should the platelet count be before surgery?
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>50,000
When should “prophylactic” platelet transfusions be given?
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With platelets <10,000
old recommendation was 20,000
What is microcytic anemia “until proven otherwise” in
a man or postmenopausal woman?
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Colon cancer
Why not infuse PRBCs with lactated Ringer’s?
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Calcium in LR may result in coagulation within the IV line (use NS)
For how long can packed RBCs be stored?
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About 6 weeks (42 days)
What is the most common cause of transfusion hemolysis?
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ABO incompatibility as a result of clerical error
What is the risk of receiving a unit of blood infected with
HIV?
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≈1 in 1,000,000
What are the symptoms of a transfusion reaction?
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Fever, chills, nausea, hypotension, lumbar pain, chest pain, abnormal bleeding
What is the treatment for transfusion hemolysis?
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Stop transfusion; provide fluids; perform diuresis (Lasix) to protect kidneys; alkalinize urine (bicarbonate); give pressors as needed
What component of the blood transfusion can cause
a fever?
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WBCs
What is the transfusion “trigger” Hct in young healthy patients?
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21%
What is the widely considered “optimal” Hct in a patient with a history of heart disease or stroke?
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≈30%
When should aspirin administration be discontinued
preoperatively?
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At 1 week because platelets live 7 to 10 days (must use judgment if patient is at risk for stroke or MI; it may be better to continue and use excellent surgical hemostasis in these patients)
What can move the oxyhemoglobin dissociation curve to the right?
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Acidosis, 2,3-DPG, fever, elevated PCO(2)
(to the right means greater ability to
release the O(2) to the tissues)
What is the normal life of RBCs?
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120 days
What is the normal life of platelets?
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7 to 10 days
What factor is deficient in hemophilia A?
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Factor VIII
How can the clotting factor for hemophilia A be remembered?
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Think: “Eight” sounds like “A”
What is the preoperative treatment of hemophilia A?
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Factor VIII infusion to 100% normal preoperative levels
What coagulation study is elevated with hemophilia A?
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PTT
How do you remember which coagulation study is affected by the hemophilias?
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There are two major hemophilias and two t’s in PTT
What factor is deficient in hemophilia B?
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Factor IX
How do you remember which factors are deficient with hemophilia A and hemophilia B?
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Think alphabetically and chronologically:
A before B—8 before 9
Hemophilia A = factor VIII
Hemophilia B = factor IX
How are hemophilias A and B inherited?
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Sex-linked recessive
What is von Willebrand’s disease?
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Deficiency of von Willebrand factor (vWF) and factor VIII:C
How is von Willebrand’s disease inherited?
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Autosomal dominant
What is used to correct von Willebrand’s disease?
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DDAVP or cryoprecipitate
What coagulation is abnormal with the following disorders:
Hemophilia A
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PTT (elevated)
What coagulation is abnormal with the following disorders:
Hemophilia B
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PTT (elevated)
What coagulation is abnormal with the following disorders:
von Willebrand’s disease
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Bleeding time
What is the effect on the coagulation system if the
patient has a deficiency in protein C, protein S, or
antithrombin III?
P128
A hypercoagulable state
What is a “left shift” on a CBC?
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Juvenile polymorphonuclear leukocytes (bands); legend has it that the old counters for all the blood cells had the lever for bands on the LEFT of the counter
What is the usual “therapeutic” PT?
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With coumadin, usually shoot for an INR of 2.0–3.0
What is the acronym basis for the word WARFARIN?
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Wisconsin Alumni Research Foundation-ARIN
What is the most common inherited hypercoagulable
state?
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Factor V Leiden
Think: LEiden = LEader
What is Xigris®?
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Activated protein C, which is used in severe sepsis