CCRN - Review Acute Respiratory Failure Questions and Answers 1 — Questions and Answers
Question 1: A patient is admitted with pneumonia and sepsis. Their arterial blood gas (ABG) on 60% FiO2 shows: pH 7.48, PaCO2 32 mmHg, PaO2 55 mmHg, HCO3 24 mEq/L. Which type of acute respiratory failure is this patient experiencing?
- Hypoxemic respiratory failure (Correct answer)
- Hypercapnic respiratory failure
- Acute-on-chronic respiratory failure
- Ventilatory failure
Correct answer: Hypoxemic respiratory failure
The patient's PaO2 is less than 60 mmHg, which is the defining characteristic of hypoxemic (Type 1) respiratory failure. The PaCO2 is low, and the pH is alkalotic, indicating the patient is hyperventilating to compensate for the hypoxemia, which is inconsistent with hypercapnic (Type 2) failure where PaCO2 would be elevated (>50 mmHg).
Question 2: A 68-year-old male with a history of COPD is brought to the emergency department with increased shortness of breath, wheezing, and purulent sputum. His ABG reveals: pH 7.28, PaCO2 65 mmHg, PaO2 58 mmHg, HCO3 28 mEq/L. Which intervention should the critical care nurse anticipate as the most appropriate initial treatment?
- Immediate endotracheal intubation and mechanical ventilation
- Administration of high-flow oxygen via a non-rebreather mask
- Non-invasive positive pressure ventilation (NIPPV) (Correct answer)
- Intravenous sodium bicarbonate administration
Correct answer: Non-invasive positive pressure ventilation (NIPPV)
Non-invasive positive pressure ventilation (NIPPV) is the recommended first-line therapy for hypercapnic respiratory failure secondary to a COPD exacerbation. It helps decrease the work of breathing, improve gas exchange, and has been shown to reduce the need for intubation and mortality. Immediate intubation is reserved for patients who fail NIPPV, have contraindications, or are in respiratory arrest. High-flow oxygen could worsen hypercapnia, and sodium bicarbonate does not address the underlying ventilatory problem.
Question 3: A patient is intubated and mechanically ventilated for Acute Respiratory Distress Syndrome (ARDS). The ventilator settings are: FiO2 0.8, PEEP 12 cm H2O, Tidal Volume 350 mL, and Respiratory Rate 22 breaths/min. The most recent PaO2 is 70 mmHg. What is the patient's PaO2/FiO2 (P/F) ratio?
- 112
- 87.5 (Correct answer)
- 250
- 314
Correct answer: 87.5
The PaO2/FiO2 (P/F) ratio is calculated by dividing the PaO2 by the FiO2 (expressed as a decimal). In this case, PaO2 = 70 mmHg and FiO2 = 0.8. Therefore, the calculation is 70 / 0.8 = 87.5. This value indicates severe ARDS.
Question 4: Which of the following is a primary cause of hypercapnic (Type II) acute respiratory failure?
- Pulmonary embolism
- Cardiogenic pulmonary edema
- Pneumonia
- Neuromuscular disease (Correct answer)
Correct answer: Neuromuscular disease
Hypercapnic respiratory failure is characterized by inadequate ventilation and carbon dioxide removal. Neuromuscular diseases, such as Myasthenia Gravis or Guillain-Barré syndrome, directly impair the function of the respiratory muscles (the 'pump'), leading to hypoventilation and a rise in PaCO2. The other options (pulmonary embolism, pulmonary edema, pneumonia) are primary causes of hypoxemic respiratory failure due to V/Q mismatch or shunting.
Question 5: A critical care nurse is caring for a patient with severe ARDS who has been placed in a prone position. The nurse understands that the primary goal of this intervention is to:
- Decrease the patient's sedation requirements.
- Improve secretion clearance and prevent ventilator-associated pneumonia.
- Increase lung compliance and functional residual capacity.
- Improve oxygenation by recruiting dependent alveoli and improving V/Q matching. (Correct answer)
Correct answer: Improve oxygenation by recruiting dependent alveoli and improving V/Q matching.
The main physiological rationale for prone positioning in ARDS is to improve oxygenation. It does so by recruiting collapsed alveoli in the dependent (posterior) lung regions, promoting more uniform lung inflation, improving ventilation-perfusion (V/Q) matching, and facilitating the drainage of secretions. While it may help with secretion clearance, its primary purpose is to enhance gas exchange.
Question 6: Which arterial blood gas finding is the hallmark of acute hypercapnic respiratory failure?
- PaO2 < 60 mmHg
- PaCO2 > 50 mmHg with a pH < 7.35 (Correct answer)
- SaO2 < 90% on room air
- HCO3 < 22 mEq/L
Correct answer: PaCO2 > 50 mmHg with a pH < 7.35
The defining characteristic of acute hypercapnic (Type II) respiratory failure is an elevated partial pressure of arterial carbon dioxide (PaCO2 > 50 mmHg) accompanied by acidemia (pH < 7.35). This indicates an acute failure of ventilation, where CO2 is produced faster than it can be eliminated. While hypoxemia (PaO2 < 60 mmHg) is often present, the primary derangement is the hypercapnia and resulting respiratory acidosis.
CCRN - Review Acute Respiratory Failure Questions and Answers 1
A patient is admitted with pneumonia and sepsis.
Their arterial blood gas (ABG) on 60% FiO2 shows: pH 7.48, PaCO2 32 mmHg, PaO2 55 mmHg, HCO3 24 mEq/L.
Which type of acute respiratory failure is this patient experiencing?