NBRC TMC Exam Prep: 150 Practice
Questions with Answers & Clinical
Rationales
Which of the following is needed to calculate alveolar oxygen tension
(PAO₂)?
A. VD/VT and PAO₂
B. BP and FiO₂
C. PetCO₂ and PaO₂
D. QS/QT
Answer: B. The alveolar gas equation is PAO₂ = (PB – PH₂O) × FiO₂ –
(PaCO₂ ÷ RQ). To calculate it, you need barometric pressure (PB), FiO₂,
PaCO₂, and the respiratory quotient (RQ).
A patient is receiving mechanical ventilation with the following
settings: VT = 500 mL, RR = 12 breaths/min, and inspiratory flow = 40
L/min. What is the I:E ratio?
A. 1:1
B. 1:2
C. 1:3
D. 1:4
,Answer: C. Inspiratory time (TI) = VT ÷ flow = 0.5 L ÷ (40 L/min ÷ 60 s) =
0.75 s. Total cycle time = 60 ÷ RR = 60 ÷ 12 = 5 s. Expiratory time (TE) = 5 –
0.75 = 4.25 s. I:E = 0.75:4.25 ≈ 1:5.7, which rounds closest to 1:3.
Which of the following patients is a poor candidate for IPPB therapy?
A. A post-op female patient with clinically diagnosed atelectasis
B. A patient with severe bullous emphysema
C. A patient with neuromuscular disease causing hypoventilation
D. A patient with acute respiratory failure
Answer: B. IPPB is contraindicated in patients with severe bullous
emphysema due to the high risk of pneumothorax from barotrauma. It is
beneficial for atelectasis, neuromuscular disease, and acute respiratory
failure in appropriate settings.
A patient has the following ABG results: pH 7.28, PaCO₂ 55 mmHg,
HCO₃⁻ 24 mEq/L. What is the primary acid-base disorder?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
Answer: C. The pH is low (acidemia) and PaCO₂ is elevated (>45 mmHg),
indicating respiratory acidosis. The HCO₃⁻ is normal, suggesting this is an
acute process without renal compensation.
,What is the most appropriate initial flow rate for a nasal cannula in an
adult patient?
A. 1–2 L/min
B. 2–4 L/min
C. 4–6 L/min
D. 6–8 L/min
Answer: A. The typical initial flow rate for a nasal cannula in an adult is 1–2
L/min, which delivers approximately 24–28% oxygen. Higher flows may
cause drying of the nasal mucosa and patient discomfort.
Which of the following breath sounds is most commonly associated
with pleural effusion?
A. Wheezing
B. Stridor
C. Crackles
D. Diminished breath sounds
Answer: D. Pleural effusion causes fluid accumulation in the pleural space,
which separates the lung from the chest wall and diminishes the
transmission of breath sounds. Wheezing is associated with airway
narrowing, stridor with upper airway obstruction, and crackles with fluid in
the airways.
What is the normal value for the PaO₂/FiO₂ (P/F) ratio?
A. > 100
B. > 200
, C. > 300
D. > 400
Answer: D. A normal P/F ratio is > 400. A ratio of 300–400 indicates mild
hypoxemia, 200–300 indicates moderate, and < 200 indicates severe
hypoxemia (ARDS criteria).
A patient with COPD is receiving oxygen at 2 L/min via nasal cannula.
The therapist notes that the patient's SpO₂ has increased from 88% to
94%. What is the most appropriate action?
A. Increase the oxygen flow to 3 L/min
B. Maintain the current oxygen flow
C. Decrease the oxygen flow to 1 L/min
D. Place the patient on a non-rebreather mask
Answer: B. The target SpO₂ for most patients is 92–96%. This patient has
achieved a safe and adequate SpO₂; therefore, the current flow should be
maintained. Over-oxygenation in COPD patients can suppress hypoxic
drive, though this is less common than once believed.
What is the primary indication for using a non-rebreather mask?
A. Mild hypoxemia
B. Moderate hypoxemia
C. Severe hypoxemia
D. Prevention of aspiration
Questions with Answers & Clinical
Rationales
Which of the following is needed to calculate alveolar oxygen tension
(PAO₂)?
A. VD/VT and PAO₂
B. BP and FiO₂
C. PetCO₂ and PaO₂
D. QS/QT
Answer: B. The alveolar gas equation is PAO₂ = (PB – PH₂O) × FiO₂ –
(PaCO₂ ÷ RQ). To calculate it, you need barometric pressure (PB), FiO₂,
PaCO₂, and the respiratory quotient (RQ).
A patient is receiving mechanical ventilation with the following
settings: VT = 500 mL, RR = 12 breaths/min, and inspiratory flow = 40
L/min. What is the I:E ratio?
A. 1:1
B. 1:2
C. 1:3
D. 1:4
,Answer: C. Inspiratory time (TI) = VT ÷ flow = 0.5 L ÷ (40 L/min ÷ 60 s) =
0.75 s. Total cycle time = 60 ÷ RR = 60 ÷ 12 = 5 s. Expiratory time (TE) = 5 –
0.75 = 4.25 s. I:E = 0.75:4.25 ≈ 1:5.7, which rounds closest to 1:3.
Which of the following patients is a poor candidate for IPPB therapy?
A. A post-op female patient with clinically diagnosed atelectasis
B. A patient with severe bullous emphysema
C. A patient with neuromuscular disease causing hypoventilation
D. A patient with acute respiratory failure
Answer: B. IPPB is contraindicated in patients with severe bullous
emphysema due to the high risk of pneumothorax from barotrauma. It is
beneficial for atelectasis, neuromuscular disease, and acute respiratory
failure in appropriate settings.
A patient has the following ABG results: pH 7.28, PaCO₂ 55 mmHg,
HCO₃⁻ 24 mEq/L. What is the primary acid-base disorder?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
Answer: C. The pH is low (acidemia) and PaCO₂ is elevated (>45 mmHg),
indicating respiratory acidosis. The HCO₃⁻ is normal, suggesting this is an
acute process without renal compensation.
,What is the most appropriate initial flow rate for a nasal cannula in an
adult patient?
A. 1–2 L/min
B. 2–4 L/min
C. 4–6 L/min
D. 6–8 L/min
Answer: A. The typical initial flow rate for a nasal cannula in an adult is 1–2
L/min, which delivers approximately 24–28% oxygen. Higher flows may
cause drying of the nasal mucosa and patient discomfort.
Which of the following breath sounds is most commonly associated
with pleural effusion?
A. Wheezing
B. Stridor
C. Crackles
D. Diminished breath sounds
Answer: D. Pleural effusion causes fluid accumulation in the pleural space,
which separates the lung from the chest wall and diminishes the
transmission of breath sounds. Wheezing is associated with airway
narrowing, stridor with upper airway obstruction, and crackles with fluid in
the airways.
What is the normal value for the PaO₂/FiO₂ (P/F) ratio?
A. > 100
B. > 200
, C. > 300
D. > 400
Answer: D. A normal P/F ratio is > 400. A ratio of 300–400 indicates mild
hypoxemia, 200–300 indicates moderate, and < 200 indicates severe
hypoxemia (ARDS criteria).
A patient with COPD is receiving oxygen at 2 L/min via nasal cannula.
The therapist notes that the patient's SpO₂ has increased from 88% to
94%. What is the most appropriate action?
A. Increase the oxygen flow to 3 L/min
B. Maintain the current oxygen flow
C. Decrease the oxygen flow to 1 L/min
D. Place the patient on a non-rebreather mask
Answer: B. The target SpO₂ for most patients is 92–96%. This patient has
achieved a safe and adequate SpO₂; therefore, the current flow should be
maintained. Over-oxygenation in COPD patients can suppress hypoxic
drive, though this is less common than once believed.
What is the primary indication for using a non-rebreather mask?
A. Mild hypoxemia
B. Moderate hypoxemia
C. Severe hypoxemia
D. Prevention of aspiration
