RRT CERTIFICATION EXAM PREP 2026 Updated
Practice Questions Comprehensive Respiratory Care
Review Detailed Explanations | Verified Answers |
Complete Success Workbook
QUESTION 1:
A 68-year-old male with a history of COPD presents with increased shortness of
breath. His arterial blood gas (ABG) reveals: pH 7.32, PaCO₂ 58 mmHg, PaO₂ 52
mmHg, HCO₃⁻ 30 mEq/L. What is the most appropriate interpretation of this
ABG?
A) Acute respiratory acidosis
B) Acute respiratory acidosis with metabolic compensation
C) Chronic respiratory acidosis with metabolic compensation
D) Metabolic alkalosis with respiratory compensation
Answer: C) Chronic respiratory acidosis with metabolic compensation
Rationale: This ABG shows respiratory acidosis (pH 7.32 < 7.35, PaCO₂ 58 > 45)
with metabolic compensation (HCO₃⁻ 30 > 26). The elevated bicarbonate indicates
renal compensation that occurs over days to weeks, suggesting chronic respiratory
acidosis. In acute respiratory acidosis, bicarbonate would be normal or only
slightly elevated. COPD patients often have chronic CO₂ retention with
compensatory metabolic alkalosis.
QUESTION 2:
What is the normal range for the A-a gradient on room air in a healthy 30-year-
old?
A) 0-5 mmHg
B) 5-15 mmHg
C) 15-25 mmHg
D) 25-35 mmHg
,Answer: B) 5-15 mmHg
Rationale: The alveolar-arterial (A-a) gradient normally increases with age. The
normal A-a gradient on room air is approximately 5-15 mmHg in young, healthy
adults. The formula to calculate expected A-a gradient is: (Age/4) + 4. For a 30-
year-old: (30/4) + 4 = 7.5 + 4 = 11.5 mmHg. An elevated A-a gradient indicates
ventilation-perfusion (V/Q) mismatch, shunting, or diffusion impairment.
QUESTION 3:
Which of the following breath sounds is characteristic of airway obstruction, such
as in asthma or COPD?
A) Crackles
B) Wheezes
C) Rhonchi
D) Pleural friction rub
Answer: B) Wheezes
Rationale: Wheezes are continuous, high-pitched musical sounds heard during
expiration (and sometimes inspiration) that indicate airway narrowing or
obstruction. They are characteristic of asthma, COPD, and bronchospasm. Crackles
(rales) are associated with fluid in the airways (pulmonary edema, pneumonia).
Rhonchi are low-pitched, snoring sounds suggesting secretions in larger airways.
Pleural friction rub indicates inflammation of the pleural surfaces.
QUESTION 4:
Calculate the PaO₂/FiO₂ (P/F) ratio for a patient on 40% oxygen (FiO₂ = 0.40) with
a PaO₂ of 80 mmHg.
A) 100
B) 150
C) 200
D) 320
,Answer: C) 200
Rationale: The P/F ratio is calculated as PaO₂ ÷ FiO₂. P/F = 80 ÷ 0.40 = 200. A
P/F ratio less than 300 indicates acute lung injury, and less than 200 indicates
ARDS (acute respiratory distress syndrome). This patient's P/F ratio of 200 meets
the criteria for ARDS (according to the Berlin Definition, which uses P/F ≤ 300
with bilateral infiltrates and no evidence of cardiogenic pulmonary edema).
QUESTION 5:
What is the most reliable indicator of adequate oxygenation in a patient receiving
mechanical ventilation?
A) Pulse oximetry (SpO₂)
B) Arterial blood gas PaO₂
C) End-tidal CO₂ (EtCO₂)
D) Respiratory rate
Answer: B) Arterial blood gas PaO₂
Rationale: While pulse oximetry (SpO₂) provides a non-invasive estimate of
oxygenation, the arterial blood gas PaO₂ is the most reliable and definitive
measurement. SpO₂ can be inaccurate in conditions such as carbon monoxide
poisoning, methemoglobinemia, poor perfusion, or dark skin pigmentation. PaO₂
directly measures the partial pressure of dissolved oxygen in arterial blood. EtCO₂
measures ventilation (CO₂ elimination), not oxygenation.
QUESTION 6:
Which of the following conditions is most likely to cause a rightward shift of the
oxyhemoglobin dissociation curve?
A) Alkalosis
B) Hypothermia
C) Increased 2,3-DPG
D) Decreased PaCO₂
, Answer: C) Increased 2,3-DPG
Rationale: A rightward shift of the oxyhemoglobin dissociation curve means
hemoglobin has a decreased affinity for oxygen, facilitating oxygen delivery to
tissues. Factors causing a rightward shift include: increased temperature, increased
2,3-DPG, acidosis (decreased pH), and increased CO₂ (Bohr effect). Leftward
shifts (increased affinity) occur with alkalosis, hypothermia, and decreased 2,3-
DPG.
QUESTION 7:
A patient has the following ABG results: pH 7.50, PaCO₂ 30 mmHg, HCO₃⁻ 24
mEq/L. This is consistent with:
A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis
D) Respiratory alkalosis
Answer: D) Respiratory alkalosis
Rationale: This ABG shows alkalemia (pH 7.50 > 7.45) with a low PaCO₂ (30 <
35), indicating respiratory alkalosis. The bicarbonate is within normal range,
suggesting this is an acute process without renal compensation yet. Respiratory
alkalosis is caused by hyperventilation from anxiety, pain, CNS disorders, or
hypoxemia. The expected compensation for acute respiratory alkalosis is a
decrease in HCO₃⁻ of 2 mEq/L for every 10 mmHg decrease in PaCO₂.
QUESTION 8:
In a patient with suspected pulmonary embolism, which of the following ABG
findings is most commonly seen?
A) Respiratory acidosis with hypoxemia
B) Respiratory alkalosis with hypoxemia
C) Metabolic acidosis with hypercapnia
D) Normal ABG
Practice Questions Comprehensive Respiratory Care
Review Detailed Explanations | Verified Answers |
Complete Success Workbook
QUESTION 1:
A 68-year-old male with a history of COPD presents with increased shortness of
breath. His arterial blood gas (ABG) reveals: pH 7.32, PaCO₂ 58 mmHg, PaO₂ 52
mmHg, HCO₃⁻ 30 mEq/L. What is the most appropriate interpretation of this
ABG?
A) Acute respiratory acidosis
B) Acute respiratory acidosis with metabolic compensation
C) Chronic respiratory acidosis with metabolic compensation
D) Metabolic alkalosis with respiratory compensation
Answer: C) Chronic respiratory acidosis with metabolic compensation
Rationale: This ABG shows respiratory acidosis (pH 7.32 < 7.35, PaCO₂ 58 > 45)
with metabolic compensation (HCO₃⁻ 30 > 26). The elevated bicarbonate indicates
renal compensation that occurs over days to weeks, suggesting chronic respiratory
acidosis. In acute respiratory acidosis, bicarbonate would be normal or only
slightly elevated. COPD patients often have chronic CO₂ retention with
compensatory metabolic alkalosis.
QUESTION 2:
What is the normal range for the A-a gradient on room air in a healthy 30-year-
old?
A) 0-5 mmHg
B) 5-15 mmHg
C) 15-25 mmHg
D) 25-35 mmHg
,Answer: B) 5-15 mmHg
Rationale: The alveolar-arterial (A-a) gradient normally increases with age. The
normal A-a gradient on room air is approximately 5-15 mmHg in young, healthy
adults. The formula to calculate expected A-a gradient is: (Age/4) + 4. For a 30-
year-old: (30/4) + 4 = 7.5 + 4 = 11.5 mmHg. An elevated A-a gradient indicates
ventilation-perfusion (V/Q) mismatch, shunting, or diffusion impairment.
QUESTION 3:
Which of the following breath sounds is characteristic of airway obstruction, such
as in asthma or COPD?
A) Crackles
B) Wheezes
C) Rhonchi
D) Pleural friction rub
Answer: B) Wheezes
Rationale: Wheezes are continuous, high-pitched musical sounds heard during
expiration (and sometimes inspiration) that indicate airway narrowing or
obstruction. They are characteristic of asthma, COPD, and bronchospasm. Crackles
(rales) are associated with fluid in the airways (pulmonary edema, pneumonia).
Rhonchi are low-pitched, snoring sounds suggesting secretions in larger airways.
Pleural friction rub indicates inflammation of the pleural surfaces.
QUESTION 4:
Calculate the PaO₂/FiO₂ (P/F) ratio for a patient on 40% oxygen (FiO₂ = 0.40) with
a PaO₂ of 80 mmHg.
A) 100
B) 150
C) 200
D) 320
,Answer: C) 200
Rationale: The P/F ratio is calculated as PaO₂ ÷ FiO₂. P/F = 80 ÷ 0.40 = 200. A
P/F ratio less than 300 indicates acute lung injury, and less than 200 indicates
ARDS (acute respiratory distress syndrome). This patient's P/F ratio of 200 meets
the criteria for ARDS (according to the Berlin Definition, which uses P/F ≤ 300
with bilateral infiltrates and no evidence of cardiogenic pulmonary edema).
QUESTION 5:
What is the most reliable indicator of adequate oxygenation in a patient receiving
mechanical ventilation?
A) Pulse oximetry (SpO₂)
B) Arterial blood gas PaO₂
C) End-tidal CO₂ (EtCO₂)
D) Respiratory rate
Answer: B) Arterial blood gas PaO₂
Rationale: While pulse oximetry (SpO₂) provides a non-invasive estimate of
oxygenation, the arterial blood gas PaO₂ is the most reliable and definitive
measurement. SpO₂ can be inaccurate in conditions such as carbon monoxide
poisoning, methemoglobinemia, poor perfusion, or dark skin pigmentation. PaO₂
directly measures the partial pressure of dissolved oxygen in arterial blood. EtCO₂
measures ventilation (CO₂ elimination), not oxygenation.
QUESTION 6:
Which of the following conditions is most likely to cause a rightward shift of the
oxyhemoglobin dissociation curve?
A) Alkalosis
B) Hypothermia
C) Increased 2,3-DPG
D) Decreased PaCO₂
, Answer: C) Increased 2,3-DPG
Rationale: A rightward shift of the oxyhemoglobin dissociation curve means
hemoglobin has a decreased affinity for oxygen, facilitating oxygen delivery to
tissues. Factors causing a rightward shift include: increased temperature, increased
2,3-DPG, acidosis (decreased pH), and increased CO₂ (Bohr effect). Leftward
shifts (increased affinity) occur with alkalosis, hypothermia, and decreased 2,3-
DPG.
QUESTION 7:
A patient has the following ABG results: pH 7.50, PaCO₂ 30 mmHg, HCO₃⁻ 24
mEq/L. This is consistent with:
A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis
D) Respiratory alkalosis
Answer: D) Respiratory alkalosis
Rationale: This ABG shows alkalemia (pH 7.50 > 7.45) with a low PaCO₂ (30 <
35), indicating respiratory alkalosis. The bicarbonate is within normal range,
suggesting this is an acute process without renal compensation yet. Respiratory
alkalosis is caused by hyperventilation from anxiety, pain, CNS disorders, or
hypoxemia. The expected compensation for acute respiratory alkalosis is a
decrease in HCO₃⁻ of 2 mEq/L for every 10 mmHg decrease in PaCO₂.
QUESTION 8:
In a patient with suspected pulmonary embolism, which of the following ABG
findings is most commonly seen?
A) Respiratory acidosis with hypoxemia
B) Respiratory alkalosis with hypoxemia
C) Metabolic acidosis with hypercapnia
D) Normal ABG
