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63 Cards in this Set
- Front
- Back
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What are the indications for urokinase therapy?
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1. PE
2. coronary artery thrombosis 3. IV catheter clearance |
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What should you give a patient requiring urgent surgery to reverse the effects of urokinase?
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1. whole blood,
2. PRBCs and cryo, 3. FFP |
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What is the mechanism of urokinase and where is it produced?
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produced in the kidney and found in the urine, converts plasminogen to plasmin which degrades clots and increases fibrin degradation products
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What does a decreased retic count imply?
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inability to synthetize RBCs
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When do you see an isolated prolonged PTT?
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hemophilia A, B and von Willebrands disease
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When do you see isolated prolonged PT?
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vit K deficiency
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When do you see both PT and PTT prolonged?
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coumadin,
heparin, chronic severe liver disease |
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What are causes of inhibited platelet fxn?
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aspirin - irreversibly acetaylates COX
uremia, von Willebrands |
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How much platelets are lost after transfusion of one blood volume?
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60-65%, if two blood volumes are transfused than 85% of platelets will be lost
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What are causes of thrombocytopenia?
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"The platelets HID"
H - Hypersplenism (cirrhosis, lymphoma), I - ITP, D - Drugs (quinidine), D - Dilutional, D- DIC |
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What is the minimum platelet count required for surgery?
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>50,000
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How long do platelets survive?
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about 10 days
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What are the three components of coagulation?
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1. vascular component (responsible for vasoconstriction),
2. platelets (responsible for forming clot) 3. procoagulants (clotting pathway/factors) |
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What is the normal PT and PTT?
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PT 12-14s,
PTT 25-35s |
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Where is factor VIII synthetised?
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reticuloendothelial system
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What are the Vit K dependent factors? Why is vitamin K necessary?
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2, 7, 9, and 10
vit K is responsible for the production of gamma carboxyglutamic acid which is essential for the proper fxn of these factors |
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What factors are shared by both the extrinsic and intrinsic pathways?
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7, 9, and 12
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What is the procoagulant problem with von Willebrand disease?
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lack of protein important for function of factor 8 as well as platelet fxn
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How is hemophilia A and hemophilia B treated?
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A - factor 8 concentrate;
B - human purified and recombinant factor 9 (1st line) and FFP (2nd line) |
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what tests are abnormal in vWD?
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PTT (due to decreased factor 8)
prolonged bleeding time (bleeding time) |
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What is the treatment of vWD?
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- best treatment is humate-P (factor VIII concentrates) or DDAVP,
- Cryo can also be given but is less efficient (40u/kg), - also FFP; - monoclonal antibody purified factor VIII alone will not compensate because of the missing platelet factor, - platelet transfusion is also ineffective |
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When can you consider regional anesthesia in patients with vWD?
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when the level of the factors is clearly above 30%
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What is the mechanism of DDAVP in vWD?
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temporarily increases various moieties of the factor VIII:vWF complex by causing their release from endothelial cells
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How do you choose between DDAVP and humate for treatment of vWD?
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- many hospitals do not have humate,
- type 1 vWD are typically DDAVP responsive but not all patients are responsive to DDAVP - If hospital doesn't have Humate and pt is poorly responsive to DDAVP tx with Cryo and FFP |
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Where is vitamin K synthetized?
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in the gut with the help of intestinal flora and then absorbed with the help of bile salts
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How long does parenteral vitamin K take to work?
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3-6 hrs
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What can cause a lack of vitamin K in the body?
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1. lack of production of vitamin K - malnutrition or antibiotic induced elimination of intestinal flora,
2. lack of absorption which can be caused by obstructive jaundice due to lack of bile salts |
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How does heparin work?
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- indirectly by means of a cofactor,
- anti-thrombin III which neutralizes several anticoagulants (IX, X, XI) and inactivates thrombin-preventing its action on fibrinogen |
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what is the half life of heparin and how is it inactivated?
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1hr;
inactivated in both liver and the kidneys |
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How does protamine antagonize heparin?
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heparin is a strong acid and protamine is a strong base
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what is the appropriate dose of protamine to antagonize heparin?
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1mg protamine/100u heparin
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What can happen if too much protamine is given to reverse heparin?
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bleeding can worsen
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What are the 3 types of reactions to protamine?
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type 1-hypotension related to rapid drug administration;
type 2- anaphylactoid reactions; type 3-catastrophic pulm htn |
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What is the best initial treatment for a severe protamine reaction?
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epinephrine followed by fluids
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what is the mechanism of tranexamic acid?
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competitive inhibitor of plasminogen activation, inhibiting the breakdown of clot (10x more potent than aminocaproic acid)
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What is the mechanism of urokinase?
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converts plasminogen to plasmin, plasmin then degrades clot increasing the amount of fibrin degradation products
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When is urokinase contraindicated?
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1. active internal bleeding,
2. hx of CVA, 3. recent intracranial surgery, 4. trauma, 5. known bleeding diathesis |
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What is the mechanism of aprotinin?
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trypsin inhibitor which inhibits plasmins fibrinolytic activity
- shown to reduce periop blood loss |
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What is determined with a type and screen?
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1. ABO and Rh status
2. presence of most commonly encountered antibodies and (Pt serum combined with Type O red cells and then antibody screen performed) |
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What is the risk of an adverse reaction after blood is type and screened?
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1:1,000
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What does a type and crossmatch tell you and what is the risk of an adverse reaction?
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1. ABO and Rh,
2. reaction to even low incidence antigens; 1:10,000 |
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How is a type and cross done?
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Two parts:
1. screen (type O red cells with known antigens) are mixed with patient serum; 2. cross - donor red cells are mixed with patient serum |
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What is the normal red cell lifetime?
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120 days
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What is the normal half life of blood stored in CPD-A and ACD?
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- CPD-A: 35 days
- ACD: 21 days |
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How much does one unit of platelets increase platelet count?
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10,000
- An 8 pack is needed to measurably increase platelet count |
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What size filters should you use when giving blood?
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-macrofilters are sufficient (200 microns),
-no difference in outcome when compared with micro filters (25-50 microns) |
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What should you do if a patient has an urticarial rxn during a blood transfusion?
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This is among the MC transfusion reactions.
If urticaria and pruritis are the only signs, usually do not have to stop the transfusion |
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What should you suspect if temperature rises 1 degree centigrade during a blood transfusion? How should you treat it?
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- febrile nonhemolytic reaction should be suspected
- give antipyretics and diphenhydramine - leukocytes are thought to be the culprit so you can give washed RBCs - consider other causes (ie febrile hemolytic reaction) |
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What are signs of a febrile hemolytic transfusion reaction?
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- may occur following infusion of only a few cc's of blood with exhaustion of haptoglobin binding capacity and lysis of cells
- fever, hypotension, hemoglobinuria, and DIC |
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An anaphylactic reaction in a pt who has been previously transfused is most often due to what?
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IgA deficiency
- usually associated with wheezing and hypotension |
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How do you treat blood transfusion reactions besides urticarial reactions?
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1. stop transfusion and support oxygenation, ventilation, and circulation (drugs i.e. epi)
2. maintain urine output (fluids, mannitol, lasix, NaHCO3) 3. send blood samples to the lab to detect free hemoglobin and for re-crossmatch, 4. check PT, PTT, platelets, and fibrinogen -If blood is desperately needed during this time O- should be used |
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what are indications for leukocyte reduced RBCs?
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1. IgA deficient patients,
2. reduces incidence of febrile, urticarial, and certain types of anaphylactic reactions |
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What are leukocyte reduced RBCs?
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washing process removes 1. plasma proteins, 2. microaggregates, 3. platelets, and 4. leukocytes
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What blood should you give in emergency situations when a full cross match isn't practical (45min)?
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1. type specific partial cross match
2. type specific uncross matched 3. O- |
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Why should you not dilute blood with LR?
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Ca in LR when combined with citrate in blood can form microclots (citrate is the anticoagulant found in donor PRBCs)
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What can happen with citrate intoxication?
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hypocalcemia with its associated problems of seizures, tetany, laryngospasm, hypotension, narrow pulse pressure, QT prolongation, elevated end diastolic pressure and CVP
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What are the indications for giving FFP?
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1. replacement of isolated factor deficiencies
2. replacement of antithrombin III deficiency, 3. documented deficiencies of factors V or VIII (less than 25%) 4. thrombotic thrombocytopenic purpura |
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What are signs of a hemolytic transfusion reaction under anesthesia? In the awake pt?
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1. hemoglobinuria
2. hypotension 3. bleeding diathesis -Awake pt: fever, fever w/ chills, nausea, flushing, dyspnea, chest and flank pain |
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What are consumed in DIC?
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1. clotting factors (esp 5 and 8)
2. Platelets 3. Fibrinogen (precursor to fibrin) |
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What are lab findings suggestive of DIC?
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1. PT > 15 s,
2. fibrinogen <150 (nml fibrinogen 150-200 (not pregnant), >300 in pregnant pt), 3. platelet count <150,000 |
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What are causes of DIC?
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SATT:
S = sepsis, A = amniotic fluid embolism, T = trauma, T = transfusion reaction |
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What is cryo used for?
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1. replace factor VIII,
2. fibrinogen, 3. fibronectin 4. von willebrands factor |
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what is the problem with commercially prepared fibrinogen?
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high incidence of associated hepatitis
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