CCRN Acute Respiratory Failure 2 — Questions and Answers
Question 1: A patient has a PaO2 of 55 mmHg on room air with a normal PaCO2. This finding is most consistent with which type of respiratory failure?
- Type I (hypoxemic) respiratory failure (Correct answer)
- Type II (hypercapnic) respiratory failure
- Chronic compensated respiratory acidosis
- Metabolic alkalosis
Correct answer: Type I (hypoxemic) respiratory failure
Type I respiratory failure is defined by hypoxemia (PaO2 < 60 mmHg) with a normal or low PaCO2.
Question 2: Which arterial blood gas finding defines Type II respiratory failure?
- PaCO2 > 45 mmHg with hypoxemia (Correct answer)
- PaO2 > 80 mmHg with normal pH
- PaCO2 < 35 mmHg
- Normal A-a gradient
Correct answer: PaCO2 > 45 mmHg with hypoxemia
Type II (hypercapnic) failure is defined by alveolar hypoventilation with PaCO2 > 45 mmHg.
Question 3: A widened alveolar-arterial (A-a) oxygen gradient with hypoxemia suggests which mechanism?
- Ventilation-perfusion mismatch or shunt (Correct answer)
- Pure hypoventilation
- High altitude exposure
- Low inspired oxygen concentration
Correct answer: Ventilation-perfusion mismatch or shunt
A widened A-a gradient indicates a gas-exchange problem such as V/Q mismatch, shunt, or diffusion impairment.
Question 4: Which condition causes hypoxemia that does NOT correct with 100% supplemental oxygen?
- Intrapulmonary shunt (Correct answer)
- V/Q mismatch
- Hypoventilation
- Low FiO2
Correct answer: Intrapulmonary shunt
True shunt allows blood to bypass ventilated alveoli, so it responds poorly to increased FiO2.
Question 5: A patient with a COPD exacerbation has pH 7.28, PaCO2 68, HCO3 30. This represents:
- Acute-on-chronic respiratory acidosis (Correct answer)
- Acute respiratory alkalosis
- Pure metabolic acidosis
- Fully compensated respiratory acidosis
Correct answer: Acute-on-chronic respiratory acidosis
The elevated HCO3 shows chronic retention, while the low pH with high CO2 indicates an acute worsening.
Question 6: Which early clinical sign most reliably indicates impending respiratory failure in an alert patient?
- Increasing accessory muscle use with rising respiratory rate (Correct answer)
- Warm dry skin
- Bradycardia at rest
- Decreased urine output
Correct answer: Increasing accessory muscle use with rising respiratory rate
Escalating work of breathing and tachypnea signal that the patient is failing to maintain gas exchange.
Question 7: A patient's PaCO2 is rising and they are becoming somnolent despite supplemental oxygen. The priority intervention is:
- Provide ventilatory support (NIV or intubation) (Correct answer)
- Increase FiO2 to 100%
- Administer a diuretic
- Encourage incentive spirometry
Correct answer: Provide ventilatory support (NIV or intubation)
Rising CO2 with declining mental status reflects ventilatory failure requiring assisted ventilation, not just more oxygen.
CCRN Acute Respiratory Failure 2
A patient has a PaO2 of 55 mmHg on room air with a normal PaCO2.
This finding is most consistent with which type of respiratory failure?