Clinical Manifestations And Assessment 7th Edition of Respiratory Disease by Terry Des Jardins – Test Bank

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Chapter 05: Oxygenation Assessments

Des Jardins: Clinical Manifestations and Assessment of Respiratory Disease, 7th Edition

MULTIPLE CHOICE

1.When a sample of arterial blood is analyzed for the pressure of oxygen (PaO₂), the value comes from the:

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 and is measured by an oximeter as the saturation, not as a partial pressure. Leukocytes do not carry oxygen.

REF: p. 70

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.

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. 74

3.A patient has been exposed to carbon monoxide during a house fire. An ABG result shows a normal PaO₂. How should the patient’s PaO₂ value be interpreted?

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 (CaO₂) is low. Remember that carbon monoxide will prevent hemoglobin from carrying oxygen.

REF: p. 78

4.A person’s C(a-v)O₂ increases in all of the following situations EXCEPT:

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. 76

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?

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. 74

6.Polycythemia is:

1. a condition of too many red blood cells.

2. a condition of too few red blood cells.

3. caused by lack of iron in the diet.

4. the body’s response to chronic hypoxemia.

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. 77-78

7.A patient has a chronic respiratory disorder and vasoconstriction of her pulmonary vascular system. What is the chief control over this vasoconstriction?

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: pp. 77-78

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.

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. 76

9.A condition that will cause hypoxic hypoxia is:

ANS: C

Hypoventilation from any cause will cause hypoxic hypoxia because an inadequate amount of oxygen is breathed in. 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. Carbon monoxide poisoning will cause anemic hypoxia because the hemoglobin cannot carry oxygen.

REF: pp. 77-78

10.A condition that will cause anemic hypoxia is:

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: pp. 77-78

11.The respiratory therapist is evaluating a patient in the intensive care unit who shows signs of tissue hypoxia. Laboratory results reveal the following: HgB 14.8 grams, CaO₂ 19.6 vol. %, PaO₂ 102 mm Hg, a-v difference 9.8 vol. %, PvO₂ 24 mm Hg. Based on these results, which of the following types of hypoxia does this patient have?

ANS: C

An increase in the a-v difference is due to a decrease in cardiac output (circulatory hypoxia). The cardiac output and a-v difference are inversely related, and an a-v difference of 9.9 vol. % is evidence of the inadequacy of the cardiac output.

REF: pp. 77-78

12.The respiratory therapist is reviewing a patient’s electronic medical record to try to verify if the patient has tissue hypoxia. Which of the following laboratory values is MOST likely to correlate with tissue hypoxia?

ANS: A

When hypoxia exists, alternate anaerobic mechanisms are activated in the tissues that produce dangerous metabolites—such as lactic acid—as waste products. Lactic acid is a nonvolatile acid and causes the pH to decrease, resulting in metabolic acidosis.

REF: p. 77

13.A patient is mildly hypoxemic. Which of the following signs would the respiratory therapist expect to find in this patient?

ANS: A

Clinically, the presence of mild hypoxemia generally stimulates the oxygen peripheral chemoreceptors to increase the patient’s breathing rate and heart rate; consequently blood pressure may slightly increase, not decrease. Cardiac dysrhythmias would not be expected with mild hypoxemia. Anemia is unrelated to mild hypoxemia.

REF: p. 77