Hematologic Disorders

Question 1

The transfussion trigger

Answer 1

A loss of more than 30% - 40% requires RBC transfusion to restore oxygen-carrying capacity

Question 2

In the case of massive transfusion (>50% blood volume replaced w/in 24 hrs) RBC may need to be accompanied with FFP and platelets in what ratio?

Answer 2

1:1:1

Question 3

A hct of 28-30% may be appropriate transfusion trigger in what patients?

Answer 3

Unstable coronary syndromes

Question 4

In what ways does Thalassemia differ from IDA?

Answer 4

Presence of a family hx of thalassemia;
Iron stores & ferritin are normal or increased;
RBC production is maintained or even disproportionately high

Question 5

How do you confirm the diagnosis of Thalassemia?

Answer 5

Hb electrophoresis which determines the types of globin chains present

Question 6

What is the result of the inability of a G6PD deficient RBC to protect itself from oxidative damage

Answer 6

Hemolysis

Question 7

Events that precipitate new or aggravate preexisting hemolysis in G6PD deficiency include:

Answer 7

Infection, metabolic conditions like DKA, certain drugs, & ingestion of fava beans

Question 8

Anesthetic risk is largely a funciton of the _________ and _____ of G6PD deficiency anemia

Answer 8

Severity & acuity

Question 9

Primary causes of macrocytic anemia in adults

Answer 9

Folic acid & B12 deficiency

Question 10

Folic acid & B12 are essential for?

Answer 10

DNA synthesis

Question 11

What is affected first by folic acid and B12 deficiency

Answer 11

High-turnover tissues such as bone marrow (unable to complete cell division. The marrow becomes megaloblasitc & macrocytic red cells are released into the circulation)

Question 12

Sustained exposure to _________ can produce an impairment of vitamin B12 activity

Answer 12

Nitrous oxide

Question 13

Sustained hypoxia results in?

Answer 13

Compensatory increase in RBC mass and Hct

Question 14

Tissue oxygen delivery is maximal at Hct of _____ & Hgb of ____

Answer 14

33%- 36%; 11-12

Question 15

How do higher Hcts with polycythemia affect oxygen delivery?

Answer 15

Increase in blood viscosity slows blood flow and decreases oxygen delivery

Question 16

When Hct rises above ______, whole-blood viscosity increases exponentially affecting blood flow especially in small blood vessels sucha s capillaries with low flow/shear rates

Answer 16

55%- 60%

Question 17

Prior to surgery, pts with hemophilia A, factor VIII level must be brought close to normal with an infusion of ________. This should be given ______ prior to surgery

Answer 17

DDAVP; 30-90 min

Question 18

One unit of single-donor apheresis platelets is equivalent to a random-donor pool of ______ units of platelets

Answer 18

4-8

Question 19

Random and single donor platelets do not need to be _____ compatible

Answer 19

ABO

Question 20

The differential diagnosis of thrombocytopenia is best organized according to the physiology of:

Answer 20

1. Platelet production;
2. Distribution in the circulation;
3. Platelet destruction

Question 21

Platelet production disorders may be caused by _________ or _________ in the bone marrow

Answer 21

Megakaryocyte hypoplasia or aplasia

Question 22

Inherited autosomal recessive;
The thrombocytopenia initially severe (<30,000 platelets) but gradually improves to normal by 2;
Often have bilateral radial anomalies & abnormalities of other bones may occur

Answer 22

Congenital hypoplastic thrombocytopenia with absent radii (TAR syndrome)

Question 23

Immune-mediated HIT occurs b/w days ______ of heparin use

Answer 23

5 and 10

Question 24

4Ts system for diagnosing HIT:

Answer 24

The degree of Thrombocytopenia;
The Timing of the platelet reduciton;
The presence of Thrombosis or other sequlae;
The presence of other causes of Thrombocytopenia

Question 25

What are the 2 types of HIT?

Answer 25

Early onset that occurs in pts exposed to heparin w/in the previous 3 months;
Delayed onset that appears after heparin is discontinued

Question 26

Thrombocytopenia unrelated to drug exposure, infection, or autoimmune disease.
High level of platelet destruction tht is balanced by high marrow production of platelets that have better-than-normal funciton

Answer 26

Autoimmune idiopathic thrombocytopenic purpura (ITP)

Question 27

Because platelets are dysfuncitonal, the ___________ does not predict bleeding risk

Answer 27

Absolute platelet number

Question 28

Tx with ______ may imporve a mild to moderate platelet defect, especially if the risk of bleeding is relatively minor

Answer 28

Desmopressin

Question 29

As a general rule, sufficient platelet transfusions to increase the percentage of normally functioning platelets to about _______ of all platelets should be sufficient to provide adequate overall platelt function for surgery

Answer 29

10% - 20%