Download Chapter 5: Oxygenation Assessments MULTIPLE CHOICE 1. When

Chapter 5: Oxygenation Assessments
MULTIPLE CHOICE
1. When a sample of arterial blood is analyzed for the pressure of oxygen (PaO2) and carbon
dioxide (PaCO2) the value comes from the:
a. blood plasma.
b. leukocytes.
c. hemoglobin.
d. erythrocytes.
ANS: A
A blood gas analyzer measures the pressure of oxygen and carbon dioxide in the blood
plasma. Oxygen is chemically bound to the hemoglobin in the erythrocytes. Leukocytes do
not carry oxygen.
REF: p. 71
2. Oxygen consumption:
1. increases with exercise.
2. is the amount of oxygen used by the body.
3. is inversely related to carbon dioxide production.
4. is about 250 mL/min in the resting adult.
a. 1, 2
b. 3, 4
c. 2, 4
d. 1, 2, 4
ANS: D
Oxygen consumption is the amount of oxygen used by the body and increases with exercise.
At rest, an adult consumes about 250 mL/min. Oxygen use is not inversely related to carbon
dioxide production.
REF: p. 73
3. Your patient has been exposed to carbon monoxide during a house fire. How should the
patient’s PaO2 value be interpreted?
a. Accurate oxygenation reading
b. Higher than actual oxygenation reading
c. False normal oxygenation reading
d. It should match the CO2 value.
ANS: C
The patient’s plasma PaO2 value may be normal or high. This can mislead the respiratory
therapist because the patient’s total oxygen value is low. Remember that carbon monoxide
will prevent hemoglobin from carrying oxygen.
REF: p. 72
4. A person’s C(a-v)O2 increases in all of the following situations EXCEPT:
a. seizures.
b. peripheral shunting.
c. hyperthermia.
d. exercise.
ANS: B
Peripheral shunting decreases the C(a-v)O2 because less oxygen is extracted by the tissues.
All of the other listed options increase oxygen extraction and so will increase the C(a-v)O2.
REF: p. 73
5. A sample of blood has been taken from a patient’s pulmonary artery. What mixed venous
oxygen saturation value (SvO2) would indicate that the patient is normal?
a. 40 mm Hg
b. 95 mm Hg
c. 75%
d. 97%
ANS: C
A normal SvO2 is 75%. Normal PvO2 is 40 mm Hg. Normal arterial blood values for oxygen
are SaO2 of 97% and PaO2 of 95 mm Hg.
REF: p. 73
6. Polycythemia:
1. is a condition of too many red blood cells.
2. is a condition of too few red blood cells.
3. is caused by lack of iron in the diet.
4. is the body’s response to chronic hypoxemia.
a. 1, 2
b. 2, 3
c. 1, 4
d. 2, 4
ANS: C
The body’s response to chronic hypoxemia is to produce too many red blood cells; this is
polycythemia. Lack of iron in the diet could lead to anemia.
REF: pp. 75-76
7. Your patient has a chronic respiratory disorder and vasoconstriction of her pulmonary
vascular system. What is the chief control over this vasoconstriction?
a. Low PAO2
b. Low PaO2
c. High PaCO2
d. High pH
ANS: A
A low PAO2 (pressure of alveolar oxygen) is primarily responsible for pulmonary
vasoconstriction. Arterial oxygen and carbon dioxide values and pH are not causes.
REF: p. 76
8. An increased cardiac output causes the:
1. C(a-v)O2 to decrease.
2. SvO2 to increase.
3. Total O2 delivery to decrease.
4. O2ER to increase.
a. 1
b. 2, 3
c. 3, 4
d. 1, 2
ANS: D
As cardiac output increases, less oxygen is extracted from the blood. Because of this, the
C(a-v)O2 decreases and SvO2 increases. Increased cardiac output would also increase total
oxygen delivery and decrease the oxygen extraction ratio.
REF: p. 73
9. A condition that will cause hypoxic hypoxia is:
a. cyanosis.
b. decreased cardiac output or heart failure.
c. hypoventilation from an overdose of a sedative medication.
d. carbon monoxide poisoning.
ANS: C
Hypoventilation from any cause will cause hypoxic hypoxia because an inadequate amount
of oxygen is breathed in. Carbon monoxide poisoning will cause anemic hypoxia because
the hemoglobin cannot carry oxygen. Cyanide poisoning will cause histotoxic hypoxia
because the tissue cells will not be able to metabolize oxygen. Decreased cardiac output or
heart failure will cause circulatory hypoxia because the heart will not deliver enough blood
and oxygen to the tissues.
REF: p. 77
10. A condition that will cause anemic hypoxia is:
a. cyanide poisoning.
b. decreased cardiac output or heart failure.
c. polycythemia.
d. carbon monoxide poisoning.
ANS: D
Carbon monoxide poisoning will cause anemic hypoxia because the hemoglobin cannot
carry oxygen. Cyanide poisoning will cause histotoxic hypoxia because the tissue cells will
not be able to metabolize oxygen. Decreased cardiac output or heart failure will cause
circulatory hypoxia because the heart will not deliver enough blood and oxygen to the
tissues. Polycythemia does not cause hypoxia.
REF: p. 77