Acute respiratory failure and mechanical ventilation represent some of the most critical and frequently encountered clinical scenarios for Adult-Gerontology Acute Care Nurse Practitioners, making this topic area essential for AGACNP-BC certification exam success. The ability to rapidly assess, diagnose, and manage patients in respiratory distress is a cornerstone competency that distinguishes acute care practitioners from other advanced practice roles. Understanding the pathophysiology of respiratory failure, including the distinction between hypoxemic and hypercapnic failure, provides the foundation for making sound clinical decisions in high-stakes situations. Mechanical ventilation management requires mastery of complex concepts including ventilator modes, lung-protective strategies, and the interpretation of ventilator waveforms and pressures. The AGACNP-BC exam heavily emphasizes evidence-based practices such as the ARDSNet protocol for acute respiratory distress syndrome, which has revolutionized critical care outcomes through low tidal volume ventilation strategies. Candidates must be proficient in recognizing life-threatening complications of mechanical ventilation, including ventilator-associated pneumonia, barotrauma, and tension pneumothorax, as these scenarios frequently appear in exam questions. The principles of ventilator weaning, including the use of spontaneous breathing trials and objective criteria like the rapid shallow breathing index, are high-yield topics that assess both knowledge and clinical judgment. Understanding arterial blood gas interpretation in the context of mechanical ventilation allows practitioners to titrate ventilator settings appropriately and recognize when interventions are needed. The exam also tests knowledge of non-invasive ventilation strategies, which have become increasingly important in preventing intubation and reducing complications in select patient populations. Advanced concepts such as permissive hypercapnia, optimal PEEP strategies, and the management of ventilator dyssynchrony demonstrate the depth of understanding required for certification. These practice questions are designed to mirror the clinical reasoning and application-level thinking required on the actual AGACNP-BC exam, helping you develop both the knowledge base and critical thinking skills necessary for success in this challenging specialty.
Practice Questions
Question 1
A patient with ARDS is on mechanical ventilation. Which ventilator setting is most consistent with lung-protective strategies?
A. Tidal volume 10 mL/kg ideal body weight
B. Tidal volume 6 mL/kg ideal body weight
C. PEEP 2 cm H2O
D. FiO2 100%
Correct Answer: B
Explanation: Lung-protective ventilation for ARDS involves using low tidal volumes of 6 mL/kg ideal body weight to prevent ventilator-induced lung injury (volutrauma and barotrauma). This strategy, supported by the ARDSNet trial, has been shown to reduce mortality in ARDS patients. Higher tidal volumes (10 mL/kg) can cause overdistension and worsen lung injury. Adequate PEEP (typically 5-15 cm H2O) is also important to prevent atelectasis, and FiO2 should be titrated to the lowest level that maintains adequate oxygenation (typically SpO2 88-95%) to avoid oxygen toxicity.
Question 2
What is the primary indication for non-invasive positive pressure ventilation (NIPPV) in acute respiratory failure?
A. Severe hypoxemic respiratory failure with altered mental status
B. Acute exacerbation of COPD with respiratory acidosis
C. Cardiac arrest
D. Upper airway obstruction
Correct Answer: B
Explanation: NIPPV (BiPAP or CPAP) is most effective for acute exacerbations of COPD with hypercapnic respiratory failure and respiratory acidosis. It reduces the work of breathing, improves gas exchange, and can prevent the need for intubation. NIPPV is contraindicated in patients with altered mental status, inability to protect the airway, hemodynamic instability, or cardiac arrest. Severe hypoxemic respiratory failure often requires intubation and mechanical ventilation. Upper airway obstruction typically requires definitive airway management with intubation.
Question 3
A mechanically ventilated patient has a plateau pressure of 35 cm H2O. What is the most appropriate intervention?
A. Increase PEEP
B. Increase tidal volume
C. Decrease tidal volume
D. Increase respiratory rate
Correct Answer: C
Explanation: Plateau pressure reflects alveolar pressure and lung compliance. A plateau pressure above 30 cm H2O increases the risk of ventilator-induced lung injury and barotrauma. The most appropriate intervention is to decrease tidal volume to reduce plateau pressure while maintaining adequate minute ventilation. This is a key component of lung-protective ventilation. Increasing PEEP or tidal volume would further increase plateau pressure. While increasing respiratory rate might be needed to maintain minute ventilation after reducing tidal volume, it doesn’t directly address the elevated plateau pressure.
Question 4
Which arterial blood gas finding is most consistent with acute respiratory failure?
A. pH 7.38, PaCO2 42, PaO2 95, HCO3 24
B. pH 7.32, PaCO2 55, PaO2 58, HCO3 26
C. pH 7.48, PaCO2 32, PaO2 98, HCO3 24
D. pH 7.35, PaCO2 45, PaO2 88, HCO3 28
Correct Answer: B
Explanation: Acute respiratory failure is defined by PaO2 <60 mmHg (hypoxemic failure) or PaCO2 >50 mmHg with pH <7.35 (hypercapnic failure). Option B shows both hypoxemia (PaO2 58) and hypercapnia (PaCO2 55) with respiratory acidosis (pH 7.32), indicating acute respiratory failure. The HCO3 of 26 suggests minimal metabolic compensation, consistent with an acute process. Option A shows normal values, Option C shows respiratory alkalosis, and Option D shows compensated respiratory acidosis without severe hypoxemia.
Question 5
What is the primary purpose of PEEP in mechanical ventilation?
A. To increase tidal volume
B. To prevent alveolar collapse and improve oxygenation
C. To decrease respiratory rate
D. To eliminate CO2
Correct Answer: B
Explanation: Positive End-Expiratory Pressure (PEEP) maintains positive pressure in the airways at the end of expiration, preventing alveolar collapse (atelectasis) and recruiting collapsed alveoli. This increases functional residual capacity and improves oxygenation by increasing the surface area available for gas exchange. PEEP is particularly important in conditions like ARDS where alveolar collapse is common. While PEEP can affect other ventilator parameters, its primary purpose is to maintain alveolar recruitment and improve oxygenation. Excessive PEEP can decrease cardiac output by reducing venous return.
Question 6
A patient on mechanical ventilation develops sudden hypoxemia, hypotension, and absent breath sounds on the right side. What is the most likely diagnosis?
A. Pulmonary embolism
B. Tension pneumothorax
C. Mucus plugging
D. Ventilator malfunction
Correct Answer: B
Explanation: The triad of sudden hypoxemia, hypotension, and unilateral absent breath sounds in a mechanically ventilated patient is classic for tension pneumothorax. This is a life-threatening emergency requiring immediate needle decompression followed by chest tube placement. Positive pressure ventilation increases the risk of pneumothorax, especially with high airway pressures. Other signs may include tracheal deviation away from the affected side, jugular venous distension, and hyperresonance to percussion. While pulmonary embolism and mucus plugging can cause hypoxemia, they don’t typically present with unilateral absent breath sounds and acute hypotension.
Question 7
Which mode of mechanical ventilation provides full ventilatory support with a set tidal volume and respiratory rate?
A. Pressure Support Ventilation (PSV)
B. Assist-Control (AC) mode
C. Continuous Positive Airway Pressure (CPAP)
D. Synchronized Intermittent Mandatory Ventilation (SIMV)
Correct Answer: B
Explanation: Assist-Control (AC) mode, also called Volume Control, delivers a preset tidal volume at a set respiratory rate. The ventilator will deliver the set rate, but if the patient initiates a breath, the ventilator will assist by delivering the full tidal volume. This provides complete ventilatory support and is commonly used for patients who cannot maintain adequate ventilation independently. PSV provides pressure support only when the patient initiates a breath. CPAP maintains constant positive pressure but doesn’t deliver breaths. SIMV delivers set breaths but allows spontaneous breathing between mandatory breaths.
Question 8
What is the target SpO2 range for most mechanically ventilated patients to avoid oxygen toxicity while maintaining adequate oxygenation?
A. 75-80%
B. 82-87%
C. 88-95%
D. 96-100%
Correct Answer: C
Explanation: The target SpO2 for most mechanically ventilated patients is 88-95%, which corresponds to a PaO2 of approximately 55-80 mmHg. This range provides adequate tissue oxygenation while minimizing the risk of oxygen toxicity from excessive FiO2. Higher oxygen levels (96-100%) may lead to absorption atelectasis, oxidative stress, and pulmonary toxicity. Lower levels risk inadequate tissue oxygenation. Exceptions include patients with carbon monoxide poisoning or severe anemia who may require higher targets, and COPD patients who may tolerate lower levels.
Question 9
A patient is being weaned from mechanical ventilation. Which parameter indicates readiness for extubation?
A. Rapid shallow breathing index (RSBI) >105
B. Negative inspiratory force (NIF) less negative than -20 cm H2O
C. Minute ventilation >15 L/min
D. Rapid shallow breathing index (RSBI) <105
Correct Answer: D
Explanation: The Rapid Shallow Breathing Index (RSBI), calculated as respiratory rate divided by tidal volume in liters, is a predictor of successful extubation. An RSBI <105 indicates a higher likelihood of successful weaning and extubation. Other criteria for extubation readiness include: adequate oxygenation (PaO2/FiO2 >150-200), hemodynamic stability, ability to protect airway, adequate cough, resolution of underlying cause, NIF more negative than -20 to -30 cm H2O, and minute ventilation <10-15 L/min. An RSBI >105 suggests rapid, shallow breathing and predicts weaning failure.
Question 10
Which complication is most associated with prolonged mechanical ventilation?
A. Ventilator-associated pneumonia (VAP)
B. Pulmonary embolism
C. Myocardial infarction
D. Acute kidney injury
Correct Answer: A
Explanation: Ventilator-associated pneumonia (VAP) is one of the most common and serious complications of prolonged mechanical ventilation, typically developing 48 hours or more after intubation. Risk factors include aspiration of oropharyngeal secretions, biofilm formation on the endotracheal tube, and impaired mucociliary clearance. Prevention strategies include elevating the head of bed to 30-45 degrees, daily sedation vacations and spontaneous breathing trials, oral care with chlorhexidine, and maintaining endotracheal tube cuff pressure. While PE, MI, and AKI can occur in critically ill patients, VAP is most directly associated with mechanical ventilation itself.
Question 11
What is the definition of ARDS based on the Berlin criteria?
A. Acute onset, bilateral infiltrates, PaO2/FiO2 <300, no cardiac cause B. Chronic dyspnea, unilateral infiltrate, PaO2/FiO2 <200 C. Acute onset, unilateral infiltrate, PaO2/FiO2 <400 D. Chronic onset, bilateral infiltrates, PaO2/FiO2 <100
Correct Answer: A
Explanation: The Berlin definition of ARDS requires: (1) acute onset within one week of known clinical insult, (2) bilateral opacities on chest imaging not fully explained by effusions or nodules, (3) respiratory failure not fully explained by cardiac failure or fluid overload, and (4) impaired oxygenation with PaO2/FiO2 ratio ≤300 mmHg with PEEP ≥5 cm H2O. ARDS is further classified by severity: mild (200-300), moderate (100-200), and severe (<100). The bilateral nature of infiltrates and exclusion of cardiogenic causes are key distinguishing features from other causes of respiratory failure.
Question 12
Which ventilator setting adjustment would most effectively improve CO2 elimination in a patient with hypercapnia?
A. Increase FiO2
B. Increase PEEP
C. Increase respiratory rate or tidal volume
D. Decrease inspiratory time
Correct Answer: C
Explanation: CO2 elimination is determined by minute ventilation, which equals tidal volume multiplied by respiratory rate. To improve CO2 elimination and reduce hypercapnia, you must increase minute ventilation by increasing either the respiratory rate or tidal volume (within lung-protective limits). Increasing FiO2 improves oxygenation but doesn’t affect CO2 elimination. PEEP primarily affects oxygenation by preventing alveolar collapse. Decreasing inspiratory time affects the inspiratory-to-expiratory ratio but doesn’t directly increase minute ventilation. In patients requiring lung-protective ventilation, increasing respiratory rate is often preferred over increasing tidal volume.
Question 13
What is the most appropriate initial FiO2 setting when intubating a patient in acute respiratory distress?
A. 0.21 (21%)
B. 0.40 (40%)
C. 0.60 (60%)
D. 1.0 (100%)
Correct Answer: D
Explanation: During emergency intubation for acute respiratory distress, the initial FiO2 should be set at 1.0 (100%) to ensure adequate oxygenation during this critical period. Once the patient is stabilized and arterial blood gases are obtained, the FiO2 should be titrated down to the lowest level that maintains adequate oxygenation (typically SpO2 88-95% or PaO2 55-80 mmHg) to minimize the risk of oxygen toxicity. Starting with 100% oxygen provides a safety margin during the high-risk intubation period and immediate post-intubation stabilization. Rapid weaning of FiO2 should follow once stability is achieved.
Question 14
A patient on mechanical ventilation has peak inspiratory pressure of 45 cm H2O and plateau pressure of 25 cm H2O. What does this indicate?
A. Decreased lung compliance
B. Increased airway resistance
C. Pneumothorax
D. ARDS
Correct Answer: B
Explanation: The difference between peak inspiratory pressure (PIP) and plateau pressure reflects airway resistance. A large gradient (>10-15 cm H2O) indicates increased airway resistance, which can be caused by bronchospasm, mucus plugging, endotracheal tube obstruction, or kinked tubing. In this case, the gradient is 20 cm H2O (45-25), indicating high airway resistance. Decreased lung compliance would cause both PIP and plateau pressure to be elevated with a normal gradient. The plateau pressure of 25 cm H2O is within acceptable limits, suggesting the lungs themselves are relatively compliant. Treatment should focus on addressing the cause of increased airway resistance.
Question 15
Which patient population would benefit most from permissive hypercapnia during mechanical ventilation?
A. Patients with increased intracranial pressure
B. Patients with ARDS requiring lung-protective ventilation
C. Patients with severe metabolic acidosis
D. Patients with pulmonary hypertension
Correct Answer: B
Explanation: Permissive hypercapnia is a strategy used in ARDS patients receiving lung-protective ventilation with low tidal volumes (6 mL/kg IBW). By accepting higher PaCO2 levels (typically 50-70 mmHg) and lower pH (as low as 7.20-7.25), clinicians can avoid increasing tidal volumes that would cause ventilator-induced lung injury. This strategy prioritizes preventing barotrauma and volutrauma over normalizing CO2. Permissive hypercapnia is contraindicated in patients with increased intracranial pressure (hypercapnia causes cerebral vasodilation and increased ICP), severe metabolic acidosis (would worsen acidemia), and pulmonary hypertension (hypercapnia can worsen pulmonary vasoconstriction).
Key Concepts for AGACNP-BC Success
– Master the ARDSNet protocol and lung-protective ventilation strategies
– Understand the differences between ventilator modes and when each is appropriate
– Practice interpreting arterial blood gases in the context of mechanical ventilation
– Know the criteria for extubation readiness and weaning parameters
– Recognize life-threatening complications of mechanical ventilation immediately
– Understand the role of PEEP in oxygenation and potential hemodynamic effects