hypoxia and cyanosis

Question 1

Reduction in oxygen saturation

Answer 1

HYPOXIA

Question 2

Factors that may bring about hypoxia

Answer 2

o Dysfunction of cardiovascular and respiratory
system.
o Inadequate inspired oxygen supply/gas
o Inadequate RBC and hemoglobin

Question 3

CAUSES AND TYPES OF HYPOXIA

Answer 3

• Anemic Hypoxia
• Carbon monoxide intoxication
• Respiratory hypoxia
• Hypoxia secondary to high altitude
• Hypoxia secondary to right to left extrapulmonary
shunting
• Specific organ hypoxia
• Increased O2 requirements
• Improper O2 utilization

Question 4

• Reduction in hemoglobin concentration

* Decline in oxygen carrying capacity

Answer 4

anemic hypoxia

Question 5

level of PaO2 in anemic hypoxia

Answer 5

Normal

Question 6

T or F
In anemic hypoxia, same quantity of oxygen is removed but with greater
degree of decline of PO2 in venous blood than
normal case.

Answer 6

True

Question 7

there is

accumulation of carboxyhemoglobin and this carboxyhemoglobin is unable to transport oxygen

Answer 7

Carbon monoxide intoxication

Question 8

if there is decrease transport of O2 the

haemoglobin oxygen dissociation curve is usually shifted to

Answer 8

left.

Question 9

T or F

CO has higher affinity to RBCs

Answer 9

T

Question 10

shift to left: Oxygen has _____ attachment to RBCs

Answer 10

increased

Question 11

T or F

There is a greater degree of tissue hypoxia in anemia than CO intoxication

Answer 11

F

Question 12

Alkalosis is associated with shift to the

Answer 12

left dissociation curve

Question 13

• Caused by pulmonary disease

* PaO2 declines in respiratory failure

Answer 13

RESPIRATORY HYPOXIA

Question 14

When respiratory failure is persistent, the hemoglobin-oxygen (Hb-O2)
dissociation curve is displaced to the

Answer 14

right

Question 15

are likely to be more
marked when depression of PaO2 results from
pulmonary disease than when the depression
occurs as the result of a decline in the fraction of
oxygen in inspired air (FIO2)

Answer 15

consequent cyanosis

Question 16

Normal FIO2

Answer 16

21

Question 17

Common findings in advanced pulmonary

disease:

Answer 17

o Ventilation-Perfusion mismatch or V-Q
mismatch

o Hypoventilation (elevated PaCO2

Question 18

PaCO2 falls secondary to anoxia-induced hyperventilation and the Hb-O2 curve is displaced to the

Answer 18

left

Question 19

High V-Q mismatch in the

Answer 19

upper lobe

Question 20

low V-Q mismatch in the

Answer 20

lower lobe

Question 21

These two forms (V/Q mismatch and
Hypoventilation) of respiratory hypoxia are
usually correctable by

Answer 21

inspiring 100% O2 for several minutes

Question 22

Respiratory locations where there is no gas

exchange

Answer 22

dead space - trachea

Question 23

conditions that may present with Shunting

Answer 23

atelectasis or AV connections in the lungs

Question 24

Main difference of V/Q mismatch and

shunting:

Answer 24

Shunting cannot be corrected by

100% oxygenation

Question 25

At higher altitude arterial saturation _______ | rapidly and symptoms becomes more serious

Answer 25

declines

Question 26

At 8,000 ft., the FIO2 is about

Answer 26

120 mmHg, alveolar PO2 is approx. 80 mmHg and SaO2 is normal.

Question 27

At 16,000 ft. FIO2 is

Answer 27

85 mmHg, alveolar PO2 is | 50 mmHg and SaO2 is 75%.

Question 28

At 5000m,

Answer 28

un-acclimatized individuals usually | cease to be able to function normally.

Question 29

o Develops in person with chronic hypoxemia secondary to prolonged residence at a high altitude (>13, 000 ft, 4200m)

Answer 29

• CHRONIC MOUNTAIN SICKNESS

Question 30

Manifestations of chronic mountain sickness

Answer 30

``` Blunted respiratory drive, decrease in ventilation, erythrocytosis, cyanosis, weakness, right ventricular enlargement secondary to pulmonary HPN and even stupor ```

Question 31

• Caused by congenital cardiac formation such as Tetralogy of Fallot, transposition of great arteries and Eisengmenger’s syndrome

Answer 31

HYPOXIA SECONDARY TO RIGHT & LEFT | EXTRAPULMONARY SHUNTING

Question 32

• PaO2 is normal but venous and tissue PO2 are reduced. • Reduced tissue perfusion and greater tissue O2 extraction • Pathophysiology leads to an increased arterialmixed venous O2 difference, or (A-V) gradient

Answer 32

Circulatory hypoxia

Question 33

conditions that may cause circulatory hypoxia

Answer 33

heart failure, shock

Question 34

specific organ hypoxia is usually brought about by:

Answer 34

``` Arterial obstruction (atherosclerosis) Raynaud’s phenomenon (vasoconstriction) ```

Question 35

• Venous obstruction and the resultant congestion and reduce arterial inflow • Edema (increases the distance of O2 diffusion) • Attempt to maintain adequate perfusion of vital organs in shock or heart failure. • Signs and symptoms of shock includes cold and clammy skin due to decrease in blood supply

Answer 35

specific organ hypoxia

Question 36

Elevated oxygen consumption without | corresponding increase in perfusion

Answer 36

INCREASED OXYGEN REQUIREMENTS

Question 37

manifestations: Increased oxygen requirements

Answer 37

• Skin is warm and flushed, cyanosis is absent | differs from other types of hypoxia

Question 38

• Reduced tissue perfusion, increased tissue | extraction of O2

Answer 38

INCREASED OXYGEN REQUIREMENTS

Question 39

MECHANISM OPERATING IN INCREASED OXYGEN | DEMAND

Answer 39

o Increased cardiac output and ventilation o Preferentially directing the blood to the exercising muscle o Increasing O2 extraction from the delivered blood o Reducing pH of the tissues and capillaries, shifting the Hb-O2curve to right

Question 40

IMPROPER OXYGEN UTILIZATION is also called

Answer 40

histotoxic hypoxia

Question 41

• Reduction of PaO2

Answer 41

o Cerebrovascular resistance decreases o Cerebral blood flow increases in an attempt to maintain O2 delivery to the brain

Question 42

However, when the reduction of PaO2 is | accompanied by hyperventilation,

Answer 42

There would be a reduction of PaCO, cerebrovascular resistance rises causing a fall in cerebral blood flow → tissue hypoxia intensifies

Question 43

o May cause impaired judgment and motor | incoordination maybe seen

Answer 43

• Acute Hypoxia

Question 44

o May cause fatigue, drowsiness, apathy, inattentiveness, delayed reaction time and reduced work capacity

Answer 44

• Longstanding Hypoxia