Hematologic Pathophysiology Anemias Flashcards
(89 cards)
1
Q
Macrocytic refers to
A
larger than normal size cells
2
Q
Microcytic refers to
A
smaller than normal size cells
3
Q
Reticulocytes are
A
immature erythrocyte (day 1 or 2 in the blood stream)
4
Q
Hemoglobin is
A
four folded globin chains (2 alpha & 2 beta)
5
Q
Hemolytic anemia is
A
abnormal hemolysis (breakdown) of RBCs
6
Q
Primary function of RBC is to
A
transport hemoglobin
-transport O2 to tissue
7
Q
1 gm of hemoglobin can combine with
A
1.34 mLs of oxygen= 100% saturation
8
Q
Red blood cells are produced in
A
bone marrow
9
Q
Any condition that decreases oxygen transport to tissues will
A
stimulate erythropoietin- a glycoprotein formed in the kidneys
10
Q
Red blood cells contain
A
carbonic anhydrase- enzyme that catalyzes the reaction between CO2 & H2O to form carbonic acid H2CO3 transport CO2 (in the form of HCO3-) to lungs for removal
11
Q
RBC production and maturation occurs with
A
pluripotent stem cell–> proerythoblast–> erythroblast–> reticulocyte–> erythrocyte
12
Q
Causes of anemia include
A
blood loss, decreased production, & increased destruction
13
Q
Describe polycythemia
A
increase in circulating RBCs- main adverse effect is increased blood viscosity
14
Q
Anemia is the
A
reduced number of circulating RBCs
15
Q
The main adverse effect of anemia is
A
decreased oxygen-carrying capcaity
16
Q
WHO defines anemia as hemoglobin concentration less than
A
12 g/dL for women & less than 13 g/dL for men
17
Q
Anemia in pregnancy is due to
A
decreased Hct in relation to increase plasma volume
18
Q
With acute blood loss, the body replaces fluid portion of
A
plasma in 1-3 days- leaving a low concentration of RBCs
the RBC concentration usually returns to normal within 3-6 weeks
19
Q
Chronic blood loss anemia is when
A
cannot absorb enough iron from the gut to make hemoglobin as rapidly as it is lost
RBCs are then produced much smaller with little Hgb inside- microcytic hypochromic anemia
20
Q
Transfusion preoperatively in asymptomatic patients for elective surgery
A
are rare
21
Q
Describe the 10/30 rule.
A
transfuse if the hemoglobin level is <10 g/dL or the Hct is <30%
- no evidence that hemoglobin levels below this level mandate transfusion
22
Q
There is clear evidence that hemoglobin levels below
A
6 g/dL benefit from transfusion
23
Q
When deciding whether to transfuse for a procedure, we must take into account
A
patient’s medical history, ongoing bleeding, and risk of end-organ dysfunction
e.g. active coronary artery disease may require lower transfusion thresholds
24
Q
RBC transfusions can transmit
A
Hep B, Hep C, HIV
25
Immunomodulatory effects of transfusion include
cancer reoccurrence, bacterial infections, transfusion related acute lung injury, & hemolytic transfusion reactions
26
Describe estimated blood loss & transfusion thresholds.
EBL <15%- rarely requires transfusion
EBL 30% replacement w/ crystalloids/albumins
EBL 30-40%- RBC transfusion
EBL >50% massive transfusion protocol- may need accompanied FFP & platelets (1:1:1 ratio)
27
Describe types of anemia that are decreased production problems.
iron deficiency
| autoimmune
28
Describe types of anemia that are increased destruction (life span <120 days).
thalassemia, hemolytic anemia, sickle cell
29
Describe types of anemia that include blood loss.
acute & chronic
30
Describe types of anemia that fall under the infectious category.
malaria parasite destroys RBCs
Babesia (parasite usually spread by ticks) causes RBC hemolysis
parovirus ("fifth disease") virus inhibits erythropoiesis
31
Types of anemia based on morphology include:
microcytic, normocytic, & macrocytic/megaloblastic
32
Iron deficiency anemia is the result of
nutritional deficiency of iron- common in infants, small children, & developing countries
- depletion of iron stores (e.g. chronic GI bleeds or mensturation)
- pregnancy
33
Iron deficiency anemia results in pregnancy because
of the increased RBC mass required during gestation
34
Mild anemia may require
preop iron
| Hb 9-12 g/dL
35
Pica is
the drive to consume non foodstuff
| because they're not getting enough iron
36
Depletion of iron stores are due to
unable to absorb sufficient iron from the diet at the same rate as chronic loss
37
_______ is required for hemoglobin synthesis
Iron
38
Iron deficiency impairs
red cell maturation & diminishes red cell production
| -produces a microcytic hypochromic anemia
39
The most important adverse effect of anemia is
decreased O2 delivery
40
Treatment of iron deficiency includes:
oral iron--> if elective surgery can be postponed for 2-4 weeks to allow correction of the iron deficiency
should be continued for at least 1 year after the
source of blood loss has been corrected
IV iron--> urgent surgery within a few weeks
RBC transfusion
41
Hemolytic anemia is due to
accelerated destruction (hemolysis) of RBC's
- removed too quickly or lysed too early
often seen in immune disorders
42
RBC lifespan is
<120 days
43
Blood tests for hemolytic anemia include
increased immature erythrocytes (reticulocytes)
unconjugated hyperbilirubinemia/jaundice
increased lactate dehydrogenase (an enzyme release from lysed RBCs)
decreased haptoglobin (a plasma protein that binds free hemoglobin)
44
Sickle cell anemia is an
autosomal recessive disorder caused by a single amino acid substitution in B-globin that creates sickle hemoglobin
45
The most common sickle cell anemia is
familial hemolytic anemia
46
Sickle cell anemia is protective against
malaria in heterozygotes
| "aka carrier"
47
In sickle cell anemia, the mutation in B-globin leads to
polymerization of sickle hemoglobin into long, stiff chains when it is deoxygenated
- cell assumes an elongated sickle shape but it returns to its normal shape when oxygenated
48
The most important variable that determines whether HbS-containing red cells undergo sickling is the
intracellular concentration of other hemoglobins
HbA- normal hemoglobin
HbF- fetal hemoglobin
49
Newborns with sickle cell anemia are asymptomatic until
HbF falls at 5-6 months of age
50
Consequences of sickling of RBCs include:
chronic hemolytic anemia
Ischemic tissue damage with episodic pain
spleen auto infarction
51
Describe chronic hemolytic anemia as a result of sickling of RBCs
repeat sickling damages the red cell membrane, eventually producing irreversible sickled cells that are removed from circulation
52
Describe ischemic tissue damage with episodic pain as a result of sickling of RBCs.
Localized obstruction in the microvasculature
- acute chest syndrome
- joints
- strokes
- retinal damage
53
Describe the implications of spleen auto infarction.
increases the risk of sepsis with encapsulated bacteria
54
Treatment for sickle cell includes:
hydroxyurea
| stem cell transplants
55
Describe what hydroxyurea does to treat sickle cell.
raises HbF levels
anti-inflammatory
decreases the rate of acute chest syndrome & blood transfusions by 50%
56
Autoimmune anemia is also known as
autoimmune hemolytic anemia
57
Autoimmune anemia is due to
antibodies (IgG & IgM) directed against a person's own RBCs
| RBCs lifespan is severely decreased
58
Causes of autoimmune anemia include
idiopathic
leukemias
infections (i.e. mononucleosis)
drug-induced (i.e. penicillin, quinidine)
59
Treatment for autoimmune anemia is
immunosuppression & steroids
60
Hemolytic disease of the newborn is due to
incompatibility between the mother & the fetus- erythroblastosis fetalis
fetus inherits red cell antigenic determinants from the father that are foreign to the mother
61
Hemolytic disease of the newborn results when the fetus is
RhD-antigen positive and mother is RhD antigen negative
62
Fetal red cells can enter maternal circulation during 3rd semester and childbirth (fetomaternal bleed) which
sensitizes the mother to paternal red cell antigens and leads to production of IgG anti-D red cell antibodies that cross the placenta & cause hemolysis of fetal red cells
63
Rhesus (Rh) factors is a
protein found on the surface of RBCs
| -its genetically inherited
64
________ antigen is the most immunogenic of all the non-ABO antigens
Rh(D)
65
Rh(D) status of an individual is normally described with
a positive or negative suffix after the ABO type (e.g. someone who is A positive has the A antigen and the Rh(D) antigen, whereas someone who is A negative lacks the Rh(D) antigen
66
Generally, the first-antigen incompatible pregnancy
does not produce disease because the mother does not produce anti-red cell IgG antibodies (the type that cross the placenta) before delivery
67
When an Rho(D) incompatibility is detected, the mother receives an
injection at 28 weeks gestation and at birth to avoid the development of antibodies towards the fetus
68
The vast majority of Rh disease is preventable in modern antenatal care by injections of
IgG anti-D antibodies (Rho(D) immune globulin) aka RhoGAM
69
G6PD deficiency is an _______
X linked genetic disease
70
G6PD is a
metabolic enzyme involve in the pentose phosphate pathway which is important in RBC metabolism
71
The half life of erythrocytes in G6PD is approximately
60 days
72
G6PD can be precipitated by
infection, DKA, medications, fava beans
73
In G6PD, ________ occurs due to inability of G6PD deficient RBCs to protect itself from
hemolysis; oxidative damage
74
G6PD deficiency peripheral smears appear to have
"bite" cells, red cells with severely damaged membranes that have portions "bitten off" by macrophages removing patches of membrane with associated hemoglobin precipitates known as Heinze bodies leading to intravascular hemolysis
75
In G6PD, the hemolysis is often transient, even with persistent infection or drug exposure, because
lysis of older cells leaves younger cells with higher levels of G6PD that are resistant to oxidant stress
76
For patients with G6PD, avoiding risk of hemolysis includes
```
not exposing the patient to oxidative drugs such as:
metoclopramide
penicillin & sulfa
methylene blue
hypothermia
acidosis
hyperglycemia
infection
```
77
Treatment of G6PD deficiency includes
no cure
avoid triggers
treat hemolytic episodes with: hydration & blood transfusions
78
Polycythemia is the result of
sustained hypoxia which results in compensatory increase in RBC mass & Hct
increases blood viscosity which slows blood flow & decreases oxygen delivery
79
Polycythemia is significant when
Hct >55-60%
- threatens vital organ perfusion
- at risk for venous/arterial thromboses
80
Relative polycythemia is also known as ____ and can be a result of
concentrated
| -dehydration, diuretics, & vomiting
81
Physiologic polycythemia occurs in
natives who live at altitudes of 14,000 to 17,000 feet
| some evidence of heritable genetic adaptation- Tibet in Asia, Andes of the Americas, Ethiopia in Africa
82
Polycythemia vera is a
stem cell (or myeloproliferative) disorder in which Hct may be as high as 60-70% instead of the normal 40-55%
83
Polycythemia vera is due to the mutation of the
Jak2 gene which doesn't stop the production of RBC when there are already too many present
-tyrosine kinase JAK2 is a signaling molecule in pathways downstream of the erythropoietin receptor & other growth factor receptors
84
Most symptoms of polycythemia vera appear in the
6th & 7th decade of life & include cyanosis, HA, dizziness, GI symptoms, hematemesis, & melena
85
With polycythemia vera, there are excess erythrocytes and possibly
platelets & leukocytes
86
Without treatment for polycythemia vera,
death from vascular complications occurs within months
- minimize risk of thrombus
- phlebotomy- helps extend survival by 10 years
- myelosuppressive drugs (e.g. hydroxyurea)
87
Anesthetic considerations for patients with polycythemia vera include
at risk for thrombosis- reduce Hct prior to surgery- phlebotomy & hydration
Hydration- NPO status vs. IV fluids
continue hydroxyurea (cytoreductive agent)
88
Effects of polycythemia vera include
total blood volume increases--> hepatic, coronary or cerebral thrombosis is common presenting sign
viscous & engorged vessels--> increases viscosity
blood passes sluggishly through skin capillaries & a greater amount becomes deoxygenated resulting in a bluish/ruddy skin appearance
Marrow fibrosis (the marrow is replaced by fibroblasts & collagen)
89
30% of patients with polycythemia vera will die from
```
cancer-leukemia (30%)
thrombotic complications (30%)
```
