ANSWER KEY Pathophysiology Focus in Acute Respiratory Conditions - Respiratory Therapist Reviewer

Acute Respiratory Distress Syndrome (ARDS)
 
1. Which of the following is the hallmark feature of ARDS?
A. Pulmonary hypertension
B. Diffuse alveolar damage with noncardiogenic pulmonary edema
C. Obstructive airway disease
D. Pleural effusion
Answer: B
Explanation: ARDS is characterized by diffuse alveolar damage leading to increased alveolar permeability and noncardiogenic pulmonary edema.
 
2. Which of the following is the most common cause of ARDS?
A. Sepsis
B. Aspiration pneumonia
C. Pulmonary embolism
D. Myasthenia gravis
Answer: A
Explanation: Sepsis is the most common cause of ARDS due to widespread inflammation and increased capillary permeability.
 
3. Which of the following is a key criterion in diagnosing ARDS?
A. Elevated left atrial pressure
B. PaO₂/FiO₂ ratio < 300 mmHg
C. Increased lung compliance
D. Normal chest X-ray
Answer: B
Explanation: A PaO₂/FiO₂ ratio < 300 mmHg indicates ARDS severity (mild: 200–300, moderate: 100–200, severe: <100).
 
4. Which ventilatory strategy is recommended for ARDS?
A. High tidal volume, low PEEP
B. Low tidal volume, high PEEP
C. Zero PEEP with high FiO₂
D. Inverse ratio ventilation
Answer: B
Explanation: Low tidal volume ventilation (6 mL/kg) with high PEEP reduces ventilator-induced lung injury in ARDS.
 
5. What is the primary goal of lung-protective ventilation in ARDS?
A. Maximize tidal volume
B. Prevent oxygen toxicity
C. Reduce ventilator-induced lung injury
D. Increase respiratory rate
Answer: C
Explanation: Lung-protective ventilation prevents barotrauma, volutrauma, and atelectrauma in ARDS patients.
 
6. Which of the following chest X-ray findings is characteristic of ARDS?
A. Hyperinflation with flattened diaphragms
B. Pleural effusion
C. Cavitary lesions in upper lobes
D. Bilateral diffuse infiltrates
Answer: D
Explanation: ARDS presents with bilateral diffuse infiltrates due to alveolar damage and pulmonary edema, without signs of heart failure.
 
7. What is the primary cause of refractory hypoxemia in ARDS?
A. Increased airway resistance
B. Ventilation-perfusion (V/Q) mismatch and shunting
C. Bronchospasm
D. Increased lung compliance
Answer: B
Explanation: Refractory hypoxemia in ARDS is caused by intrapulmonary shunting and V/Q mismatch due to alveolar collapse.
 
Acute Exacerbations of Chronic Respiratory Diseases
 
8. Which of the following is a common trigger for acute exacerbation of COPD?
A. Pulmonary embolism
B. Viral or bacterial infection
C. Pneumothorax
D. Lung cancer
Answer: B
Explanation: Respiratory infections (bacterial or viral) are the most common cause of COPD exacerbations.
 
9. Which arterial blood gas (ABG) pattern is expected in acute exacerbation of COPD?
A. Respiratory acidosis
B. Metabolic acidosis
C. Respiratory alkalosis
D. Metabolic alkalosis
Answer: A
Explanation: COPD exacerbations lead to respiratory acidosis due to CO₂ retention and impaired ventilation.
 
10. Which medication is the first-line treatment for acute COPD exacerbation?
A. Long-acting beta-agonist (LABA)
B. Inhaled corticosteroids
C. Short-acting beta-agonist (SABA)
D. Montelukast
Answer: C
Explanation: Short-acting beta-agonists (SABA) such as albuterol provide rapid bronchodilation during COPD exacerbations.
 
11. Which of the following is a hallmark feature of an asthma exacerbation?
A. FEV₁/FVC > 80%
B. Decreased airway resistance
C. Pulsus paradoxus
D. Hypercapnia at onset
Answer: C
Explanation: Pulsus paradoxus (drop in BP during inspiration) is a sign of severe asthma exacerbation.
 
12. Which intervention is most appropriate in severe asthma exacerbation unresponsive to bronchodilators?
A. Magnesium sulfate IV
B. Nebulized anticholinergics
C. Montelukast
D. Long-acting beta-agonist (LABA)
Answer: A
Explanation: Magnesium sulfate acts as a smooth muscle relaxant, reducing bronchospasm in refractory asthma.
 
13. Which of the following signs is a red flag in an acute COPD exacerbation?
A. Increased sputum production
B. Accessory muscle use and paradoxical breathing
C. Mild wheezing
D. Increased breath sounds
Answer: B
Explanation: Accessory muscle use and paradoxical breathing indicate respiratory distress and possible impending respiratory failure.
 
14. Which of the following medications is most effective in treating an acute asthma exacerbation?
A. Inhaled corticosteroids
B. Long-acting beta-agonists (LABA)
C. Short-acting beta-agonists (SABA)
D. Leukotriene receptor antagonists
Answer: C
Explanation: SABA (e.g., albuterol) provides rapid bronchodilation, making it the first-line treatment for asthma exacerbations.
 
15. Which of the following is NOT a common feature of a severe asthma attack?
A. Respiratory acidosis
B. Silent chest
C. Bradycardia
D. Hypercapnia
Answer: C
Explanation: Bradycardia is not common in asthma; tachycardia due to hypoxia and stress is expected. Bradycardia suggests impending respiratory failure.
 
Respiratory Failure (Hypoxemic and Hypercapnic)
 
16. Which ABG finding is characteristic of Type 1 (hypoxemic) respiratory failure?
A. PaO₂ < 60 mmHg, PaCO₂ > 50 mmHg
B. PaO₂ < 60 mmHg, PaCO₂ normal or low
C. PaO₂ > 80 mmHg, PaCO₂ > 50 mmHg
D. PaO₂ < 80 mmHg, PaCO₂ < 40 mmHg
Answer: B
Explanation: Type 1 respiratory failure is defined as low PaO₂ (<60 mmHg) with normal or low PaCO₂.
 
17. Which condition is a common cause of hypercapnic (Type 2) respiratory failure?
A. Pulmonary embolism
B. Asthma
C. Opioid overdose
D. Pneumonia
Answer: C
Explanation: Opioid overdose leads to hypoventilation, causing CO₂ retention and hypercapnic respiratory failure.
 
18. Which non-invasive intervention is preferred for a COPD patient in hypercapnic respiratory failure?
A. High-flow nasal cannula
B. Invasive mechanical ventilation
C. Non-invasive positive pressure ventilation (NIPPV)
D. Supplemental oxygen alone
Answer: C
Explanation: NIPPV (e.g., BiPAP) supports ventilation and reduces CO₂ retention in COPD patients with respiratory failure.
 
19. What is the hallmark of impending respiratory failure in an asthmatic patient?
A. Wheezing
B. Tachycardia
C. Hyperventilation
D. Silent chest
Answer: D
Explanation: Silent chest indicates severe airway obstruction and impending respiratory collapse.
 
20. What is the main cause of hypoxemia in ARDS?
A. Hypoventilation
B. Ventilation-perfusion mismatch
C. Airway obstruction
D. Hypercapnia
Answer: B
Explanation: V/Q mismatch due to alveolar damage and fluid accumulation leads to severe hypoxemia in ARDS.
 
21. Which laboratory test helps distinguish between cardiogenic and noncardiogenic pulmonary edema?
A. Brain natriuretic peptide (BNP)
B. D-dimer
C. Troponin
D. C-reactive protein
Answer: A
Explanation: BNP is elevated in cardiogenic pulmonary edema (heart failure) but normal in noncardiogenic causes like ARDS.
 
22. What is the preferred method of oxygen therapy for a patient with COPD and mild hypoxemia?
A. High-flow nasal cannula
B. Venturi mask
C. Non-rebreather mask
D. Simple face mask
Answer: B
Explanation: A Venturi mask delivers precise FiO₂ levels, preventing excessive oxygenation and CO₂ retention in COPD patients.
 
23. A patient in respiratory failure has a pH of 7.28, PaCO₂ of 65 mmHg, and HCO₃⁻ of 27 mEq/L. What is the diagnosis?
A. Metabolic acidosis
B. Acute respiratory alkalosis
C. Metabolic alkalosis
D. Acute respiratory acidosis
Answer: D
Explanation: Respiratory acidosis is characterized by elevated PaCO₂ and decreased pH, indicating hypoventilation.
 
24. Which of the following is a sign of impending respiratory failure?
A. Tachycardia
B. Bradypnea and lethargy
C. Mild dyspnea
D. Normal oxygen saturation
Answer: B
Explanation: Bradypnea and lethargy suggest CO₂ retention and exhaustion, indicating impending respiratory failure.
 
Miscellaneous Acute Respiratory Conditions
 
25. Which of the following is an early sign of acute respiratory failure?
A. Bradycardia
B. Confusion and agitation
C. Cyanosis
D. Hypotension
Answer: B
Explanation: Altered mental status (confusion, agitation) is an early indicator of respiratory failure.
 
26. Which of the following oxygen delivery methods provides the highest FiO₂?
A. Non-rebreather mask
B. Simple face mask
C. Nasal cannula
D. Venturi mask
Answer: A
Explanation: Non-rebreather masks deliver FiO₂ up to 90%, making them useful in acute hypoxemia.
 
27. Which of the following conditions causes an increased A-a gradient (alveolar-arterial oxygen difference)?
A. Hypoventilation
B. High altitude exposure
C. Pulmonary embolism
D. Opioid overdose
Answer: C
Explanation: A pulmonary embolism causes impaired perfusion, leading to an increased A-a gradient and V/Q mismatch.
 
28. Which of the following signs suggests a tension pneumothorax?
A. Bilateral wheezing
B. Bilateral crackles
C. Increased tactile fremitus
D. Tracheal deviation away from the affected side
Answer: D
Explanation: Tension pneumothorax causes tracheal deviation away from the affected lung due to increased pressure.
 
29. A patient with acute dyspnea and pleuritic chest pain has a PaO₂ of 55 mmHg on room air. Which condition is most likely?
A. Asthma
B. Pulmonary embolism
C. Bronchiectasis
D. Pleural effusion
Answer: B
Explanation: Pulmonary embolism causes acute hypoxemia, pleuritic chest pain, and dyspnea due to blocked pulmonary circulation.
 
30. Which test confirms the diagnosis of a pulmonary embolism?
A. Chest X-ray
B. Electrocardiogram (ECG)
C. Spirometry
D. CT pulmonary angiography
Answer: D
Explanation: CT pulmonary angiography is the gold standard for diagnosing pulmonary embolism by detecting intravascular thrombi.