MSNC 505 WEEK 7: ADVANCED
PATHOPHYSIOLOGY AND CRITICAL
CARE QUESTIONS AND DETAILED
SOLUTIONS JUST RELEASED
1. A patient with ARDS is being treated with PEEP. What is the primary pathophysiological
mechanism by which PEEP improves oxygenation?
A. By decreasing the anatomical dead space in the upper airway.
B. By increasing the fraction of inspired oxygen reaching the tracheobronchial tree.
C. By decreasing the systemic vascular resistance and improving cardiac output.
D. By recruiting collapsed alveoli and increasing functional residual capacity.
Answer: D
Conceptual Explanation: PEEP (Positive End-Expiratory Pressure) functions by
preventing alveolar collapse at the end of expiration, recruiting previously collapsed units,
and increasing functional residual capacity (FRC), which reduces intrapulmonary shunting.
2. In the context of the oxyhemoglobin dissociation curve, which of the following conditions
would cause a ‘right shift’, thereby decreasing hemoglobin’s affinity for oxygen?
A. Hypothermia and alkalosis.
B. Hypocapnia and decreased 2,3-DPG.
,C. Hyperthermia, acidosis, and increased 2,3-DPG.
D. Severe carbon monoxide poisoning.
Answer: C
Conceptual Explanation: A right shift occurs in response to metabolic needs (exercise,
fever, acidosis), allowing oxygen to be released more easily to the tissues. Factors include
increased temperature, increased H+ ions (acidosis), and increased 2,3-DPG.
3. Which type of respiratory failure is characterized by a V/Q ratio of zero, representing a
condition where blood flows through the lungs without participating in gas exchange?
A. Anatomical dead space.
B. Alveolar dead space.
C. Intrapulmonary shunting.
D. Diffusion limitation.
Answer: C
Conceptual Explanation: Intrapulmonary shunting (V/Q = 0) occurs when blood passes
through pulmonary capillaries that are in contact with non-ventilated alveoli, such as in
pneumonia, pulmonary edema, or atelectasis.
4. During the fibroproliferative phase of ARDS, what is the primary structural change
occurring in the lung parenchyma?
A. Destruction of type I pneumocytes and hyaline membrane formation.
, B. Resolution of edema and restoration of surfactant production.
C. Massive influx of neutrophils and release of cytokines.
D. Disorganized collagen deposition and myofibroblast proliferation.
Answer: D
Conceptual Explanation: The fibroproliferative phase follows the initial exudative phase
and is characterized by the attempt to repair the lung, leading to collagen deposition,
fibrosis, and reduced lung compliance.
5. A patient presents with a pH of 7.25, PaCO2 of 55 mmHg, and HCO3 of 28 mEq/L. How
would you classify this acid-base disturbance?
A. Compensated metabolic acidosis.
B. Fully compensated respiratory alkalosis.
C. Uncompensated metabolic alkalosis.
D. Partially compensated respiratory acidosis.
Answer: D
Conceptual Explanation: The pH is low (acidosis), the PaCO2 is high (respiratory cause),
and the HCO3 is elevated (indicating the kidneys have started to compensate but haven’t
returned the pH to normal), making it partially compensated respiratory acidosis.
PATHOPHYSIOLOGY AND CRITICAL
CARE QUESTIONS AND DETAILED
SOLUTIONS JUST RELEASED
1. A patient with ARDS is being treated with PEEP. What is the primary pathophysiological
mechanism by which PEEP improves oxygenation?
A. By decreasing the anatomical dead space in the upper airway.
B. By increasing the fraction of inspired oxygen reaching the tracheobronchial tree.
C. By decreasing the systemic vascular resistance and improving cardiac output.
D. By recruiting collapsed alveoli and increasing functional residual capacity.
Answer: D
Conceptual Explanation: PEEP (Positive End-Expiratory Pressure) functions by
preventing alveolar collapse at the end of expiration, recruiting previously collapsed units,
and increasing functional residual capacity (FRC), which reduces intrapulmonary shunting.
2. In the context of the oxyhemoglobin dissociation curve, which of the following conditions
would cause a ‘right shift’, thereby decreasing hemoglobin’s affinity for oxygen?
A. Hypothermia and alkalosis.
B. Hypocapnia and decreased 2,3-DPG.
,C. Hyperthermia, acidosis, and increased 2,3-DPG.
D. Severe carbon monoxide poisoning.
Answer: C
Conceptual Explanation: A right shift occurs in response to metabolic needs (exercise,
fever, acidosis), allowing oxygen to be released more easily to the tissues. Factors include
increased temperature, increased H+ ions (acidosis), and increased 2,3-DPG.
3. Which type of respiratory failure is characterized by a V/Q ratio of zero, representing a
condition where blood flows through the lungs without participating in gas exchange?
A. Anatomical dead space.
B. Alveolar dead space.
C. Intrapulmonary shunting.
D. Diffusion limitation.
Answer: C
Conceptual Explanation: Intrapulmonary shunting (V/Q = 0) occurs when blood passes
through pulmonary capillaries that are in contact with non-ventilated alveoli, such as in
pneumonia, pulmonary edema, or atelectasis.
4. During the fibroproliferative phase of ARDS, what is the primary structural change
occurring in the lung parenchyma?
A. Destruction of type I pneumocytes and hyaline membrane formation.
, B. Resolution of edema and restoration of surfactant production.
C. Massive influx of neutrophils and release of cytokines.
D. Disorganized collagen deposition and myofibroblast proliferation.
Answer: D
Conceptual Explanation: The fibroproliferative phase follows the initial exudative phase
and is characterized by the attempt to repair the lung, leading to collagen deposition,
fibrosis, and reduced lung compliance.
5. A patient presents with a pH of 7.25, PaCO2 of 55 mmHg, and HCO3 of 28 mEq/L. How
would you classify this acid-base disturbance?
A. Compensated metabolic acidosis.
B. Fully compensated respiratory alkalosis.
C. Uncompensated metabolic alkalosis.
D. Partially compensated respiratory acidosis.
Answer: D
Conceptual Explanation: The pH is low (acidosis), the PaCO2 is high (respiratory cause),
and the HCO3 is elevated (indicating the kidneys have started to compensate but haven’t
returned the pH to normal), making it partially compensated respiratory acidosis.
