Heme

Question 1

How are the mechanisms of unfractionated heparin and LWMH the same? Different?

Answer 1

Both bind ATIII

heparin-ATIII inhibits thrombin and Xa equally

LMWH-ATIII preferntially inhibits Xa

Question 2

What are the two types of HIT?

Answer 2

type I: mild, caused by platelet aggregation

type II: severe, caused by activated platelets that adhere, aggregate, and forms clots

Question 3

What are the vitamin K-dependent clotting factors affected by Coumadin?

Answer 3

II, VII, IX, and X

protein C and S

Question 4

How does DDAVP improve hemostasis?

Answer 4

increaes plasma levels of vWF and factor VIII

Question 5

What does cryoprecipitate contain?

Answer 5

vWF, factor VIII, factor XIII, and fibrinogen

Question 6

How should subsequent transfusion be managed when a patient has received emergency release whole blood?

Answer 6

After two units, the patient should continue to get type O blood because they will accumulate anti-A and anti-B antibodies.

Question 7

How does recombinant factor VII facilitate hemostasis?

Answer 7

It directly activates factor X on activated platelets (independent of factors VIII and IX) and causes a “thrombin burst” and a stable fibrin clot

Question 8

What are the three pedominant roles of vWF in hemostasis?

Answer 8

binding platelets to the subendothelium (via GPIb)

binding activated platelets to each other (via GPIIb/IIIa)

stabilizing carrier for inactive factor VIII

Question 9

What are the three types of von Willebrand’s disease?

Answer 9

type 1: mild deficiency of normal vWF

type 2: mutant vWF (mostly affecting multimerization)

type 3: severe deficiency of normal vWF

Question 10

What type of von Willebrand’s disease is responsive to ddAVP?

Answer 10

type 1

Question 11

What is the primary activator of factor X on the platelet surface?

Answer 11

complex of factors VIII and IX

Question 12

How does platelet aggregation occur?

Answer 12

GPIIb/IIIa receptors are exposed on activated platelets and crosslinked by vWF and fibrinogen

Question 13

What is the role of factor XIII in coagulation?

Answer 13

cross-polymerization of fibrin to form a firmer clot

Question 14

What is the role of factor V in coagulation?

Answer 14

co-factor for factor Xa to achieve thrombin activation

Question 15

What factors limit clot extension?

Answer 15

tissue factor pathway inhibitor blocks tissue factor actiation of factor X

protein C (and co-factor protein S) inactivate factor Va and factor VIIIa

tPA initiates fibrinolysis

Question 16

Why might patients with hemophilia A fail to respond to factor VIII infusion? How can they be managed?

Answer 16

30% will develop a neutralizing antibody

can treat with recombinant factor VII, IVIG, plasma exchange

Question 17

What are the indications for FFP?

Answer 17

factor deficiency

reversal of coumadin

ATIII deficiency

hereditary angioedema (if C1-esterase inhibitor unavailable)

massive transfusion

Question 18

Can TXA be used in patients with hemophilia A?

Answer 18

Yes, but only documented to be effective with minor bleeding

Question 19

What kinds of bleeding are best treated by recombinant factor VII?

Answer 19

bleeding confined to a few localized sites, not diffuse bleeding

Question 20

How long are factor VIII levels supplemented after surgery in patients with hemophilia A?

Answer 20

2-4 weeks

Question 21

What part of the hemoglobin molecule is affected by sickle cell anemia?

Answer 21

beta globin chain

Question 22

What are the four kinds of sickle cell crises?

Answer 22

vaso-occlusive

splenic sequestration

aplastic (usually parvovirus B19)

hemolytic (usually with G6PD deficiency)

Question 23

What is acute chest syndrome? How is it treated?

Answer 23

New infiltrate and pulmonary symptoms similar to PNA often following a vaso-occlusive crisis

Treat with antibiotics, bronchodilators, and exchange transfusion

Question 24

What are the pre-operative transfusion goals for sickle cell anemia?

Answer 24

Hgb > 8

Hgb A fraction > 40%

Question 25

What are the anesthetic considerations particular to sickle cell anemia?

Answer 25

maintain O₂ content

maintain normothermia

avoid acidosis

avoid touriquet use

avoid venous stasis

avoid hypovolemia