ABG Sample TMC Practice Questions (Arterial Blood Gases)

An arterial blood gas (ABG) test measures oxygen and carbon dioxide levels in a patient’s blood. It is used to check the acid-base balance and oxygen saturation of arterial blood.

It should go without saying that respiratory therapists (and students) must be experts on the topic of ABG interpretation.

In this guide, we’ve listed some sample TMC practice questions on arterial blood gases. This can help you practice and prepare with questions similar to what you’ll see on the licensure exam offered by the NBRC.

ABG Sample TMC Practice Questions:

1. An adult patient with shortness of breath is admitted to the emergency department. An ABG has been collected and shows the following results:
pH 7.51
PaCO2 26 torr
PaO2 57 torr
HCO3- 24 mEq/L
Which of the following best describes the patient’s status?
A. The patient has a metabolic issue
B. The patient is hypoventilating
C. The primary concern is hypoxemia
D. The patient is in impending respiratory failure

2. The physician put in an order for an ABG that was not STAT. You weren’t busy so you went ahead and collected the sample. What is the best way to avoid analysis errors associated with running the sample?
A. Analyze the sample immediately
B. Place the sample in an ice slush
C. Use dry instead of liquid heparin
D. Uncap the syringe to remove any air

3. The physician ordered an ABG on a 41-year-old patient with COPD. Before drawing the sample from the radial artery, which of the following should be performed?
A. Check the patient’s oxygen saturation
B. Modified Allen test
C. Nail bed blanching
D. Blood pressure measurement

4. A 48-year-old female patient has been admitted to the emergency department with the following arterial blood gas results:
pH 7.54
PaCO2 29 torr
PaO2 86 torr
HCO3- 24 mEq/L
Which of the following is the best interpretation of these results?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis

5. You are needed to help with the treatment of a patient with pneumonia that is receiving oxygen via nasal cannula at 4 L/min. The physician asks for your suggestion of the best way to evaluate the patient’s overall ability to breathe. What should you recommend?
A. Performing pulse oximetry
B. Drawing an arterial blood sample for analysis
C. Performing a forced vital capacity measurement
D. Doing a full set of pulmonary function tests

6. A 56-year-old male patient’s status has gotten worse over the past 2 hours. He went from an air entrainment mask to a nonrebreather, and is now receiving positive pressure ventilation with the following settings:
Assist control rate of 12
Tidal volume 650 mL
FIO2 100%
PIP 40 cm H2O
Plateau pressure 35 cm H2
The patient’s arterial blood gas results are:
pH 7.42
PaCO2 35 torr
PaO2 54 torr
SpO2 84%
HCO3- 23 mEq/L
Which of the following best represents the status of this patient?
A. Cystic fibrosis
B. Acute metabolic alkalosis
C. Hypoventilation from fatigue
D. A significant intrapulmonary shunt

7. A 60-year-old female patient has been admitted to the emergency department with the following ABG results:
pH 7.48
PaCO2 41 torr
PaO2 98 torr
HCO3- 52 mEq/L
These results of this ABG can be interpreted as:
A. Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Metabolic acidosis

8. An ABG is drawn on 71-year-old patient with a history of chronic COPD. After reviewing the patient’s ABG results, which of the following values would be most reflective of the severity of the patient’s chronic condition?
A. pH
B. PaCO2
C. HCO3-
D. PaO2

9. A patient has been admitted to the emergency department with the following arterial blood gas results:
pH 7.24
PaCO2 29 torr
PaO2 81 torr
HCO3- 13 mEq/L
Which of the following best describes the given results?
A. Partially compensated metabolic alkalosis
B. Partially compensated metabolic acidosis
C. Uncompensated respiratory acidosis
D. Uncompensated respiratory alkalosis

10. The following ABG results were obtained on a 54-year-old female patient that is breathing room air:
pH 7.30
PaCO2 57 torr
PaO2 61 torr
HCO3- 24 mEq/L
Which of the following best describes the given results?
A. Normal blood gas with mild hypoxemia
B. Fully compensated metabolic acidosis with mild hypoxemia
C. Acute respiratory alkalosis with mild hypoxemia
D. Acute uncompensated respiratory acidosis with mild hypoxemia

11. A patient with acute respiratory acidosis would be expected to have a base excess in the range of which of the following?
A. + 6 mEq/L
B. – 6 mEq/L
C. +/- 2 mEq/L
D. +/- 8 mEq/L

12. Which of the following ABG results would you most likely see for a patient who is having a mild asthma attack?
A. pH = 7.30 PaCO2 = 49 torr PaO2 = 61 torr
B. pH = 7.41 PaCO2 = 51 torr PaO2 = 51 torr
C. pH = 7.45 PaCO2 = 42 torr PaO2 = 52 torr
D. pH = 7.47 PaCO2 = 30 torr PaO2 = 62 torr

13. The following ABG results were obtained on a 28-year-old female patient:
pH 7.28
PaCO2 22 torr
HCO3 12 mEq/L
BE -13
PaO2 111 torr
Her ABG results indicate which of the following?
A. Acute metabolic alkalosis
B. Partially compensated metabolic acidosis
C. Partially compensated respiratory alkalosis
D. Acute respiratory acidosis

14. A 61-year-old female patient with a history of COPD was admitted to the emergency department for an acute case of suspected pneumonia. Her ABG results are as follows:
pH = 7.19
PCO2 = 66 torr
HCO3 = 26 mEq/L
PaO2 = 41 torr
P(A-a)O2 = 43 torr
Which of the following best describes the patient’s condition?
A. Acute hypercapnic respiratory failure
B. Chronic hypercapnic respiratory failure
C. Acute hypoxemic respiratory failure
D. Combined hypercapnic and hypoxemic respiratory failure

15. A 48-year-old male patient is receiving volume-control SIMV with 40% oxygen and has the following ABG results:
pH 7.51
PaCO2 27 torr
PaO2 85 torr
HCO3 24 mEq/L
BE -1
The patient’s blood gas results indicate which of the following?
A. Acute respiratory alkalosis
B. Acute respiratory acidosis
C. Acute metabolic alkalosis
D. Acute hypoxemic failure

16. Which of the following problems is most likely associated with a patient whose ABG results show respiratory alkalosis?
A. Hypoxemia
B. Hypothermia
C. CNS depression
D. Opiate overdose

17. A 54-year-old female patient on the general floor has the following ABG results:
pH = 7.53
pCO2 = 44 torr
HCO3 = 34 mEq/L
Which of the following is the best interpretation of these results?
A. Acute respiratory alkalosis
B. Acute metabolic alkalosis
C. Compensated respiratory alkalosis
D. Combined respiratory and metabolic alkalosis

18. While interpreting a patient’s ABG results, you note a PaCO2 of 24 torr, a Base Excess of -11 mEq/L, and a pH of 7.36. How would you interpret these results?
A. Acute respiratory alkalosis
B. Acute metabolic acidosis
C. Compensated respiratory alkalosis
D. Compensated metabolic acidosis

19. A 69-year-old male patient in the ICU displays the following ABG results:
pH = 7.43
pCO2 = 21 torr
HCO3 = 13 mEq/L
His ABG results can be interpreted as which of the following?
A. Acute respiratory alkalosis
B. Partially compensated respiratory alkalosis
C. Fully compensated respiratory alkalosis
D. Combined respiratory and metabolic alkalosis

20. A patient’s ABG results show that she has a pH of 7.56 and a PaCO2 of 48 torr. Based on the results given, how would you interpret the patient’s status?
A. Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Metabolic alkalosis

21. You were just called by the physician for a STAT ABG. Before entering the patient’s room, you must first gather all the necessary supplies. Which of the following is required in order to perform an arterial puncture?
A. Sterile gloves
B. Lancet
C. Local anesthetic
D. Anticoagulant

22. There is an order to obtain a blood sample from a neonate. It is determined that you should obtain the sample from a capillary instead of the artery. Which of the following is true regarding a capillary blood gas sample?
A. To obtain the sample, you need to milk the puncture site
B. The sample must be drawn from the first drop of surface blood
C. The pH and PCO2 correlate well with arterial blood
D. The puncture normally is performed on the ball of the foot

23. Which of the following infection control procedures is to be used when drawing an arterial blood gas?
A. Hand washing and gloves only
B. Gown and protective eyewear
C. Mask and protective eyewear
D. All CDC standard precautions

24. After collecting an ABG sample, you are about the analyze the sample using a point-of-care analyzer. During the process, the device flags the PaCO2 results. Which of the following should you do at this time?
A. Send the sample to the central lab for analysis
B. Repeat the analysis using a fresh sample and the same cartridge
C. Repeat analysis using a fresh sample and new cartridge
D. Repeat the analysis using the same sample and same cartridge

25. A patient in the emergency department is receiving oxygen via a nonrebreather at 15 L/min. There ABG results are as follows:
pH 7.21
PaCO2 38 torr
PaO2 569 torr
SpO2 100%
HCO3 23 mEq/L
BE -1
Which of the following is the best interpretation for these results?
A. Respiratory acidosis
B. Metabolic acidosis
C. Laboratory error
D. Large physiologic shunt

26. A 51-year-old patient on room air has the following ABG results:
pH 7.43
PaCO2 47 torr
PaO2 169 torr
Which of the following is the best action to take?
A. Report the results to the attending physician
B. Report the results to the patient’s nurse
C. Discard the sample and obtain a new one
D. Give the patient a bronchodilator treatment

27. A patient with a flail chest arrives to the emergency department and is hyperventilating. Which of the following ABG results would you expect to find for this patient?
A. Increased pH and decreased SaO2
B. Increased pH and increased SaO2
C. Decreased pH and decreased SaO2
D. Decreased pH and increased SaO2

28. After drawing an ABG sample, you notice that the blood appears to be darker in color. You suspect that obtained sample is actually venous blood. Which of the following would be the best way to confirm this suspicion?
A. Get a second opinion from the attending physician
B. Compute the alveolar-arterial O2 gradient
C. Compute the patient’s P/F ratio
D. Cross-check the results against the patient’s SpO2

29. A 176 lb male patient is intubated and receiving volume control A/C ventilation. His settings are as follows: 40% FiO2 at a rate of 12/min and a VT of 550 mL. A blood gas was drawn and bedside measurements display the following results:

Which of the following actions would be appropriate at this time?
A. Place the patient on a 40% T-tube and monitor closely
B. Switch the patient to SIMV at a rate of 5/minute
C. Place the patient on 5 cm H2O CPAP and monitor closely
D. Maintain the current ventilator settings and re-evaluate later

30. A 57-year-old female patient with emphysema has the following ABG results:
pH 7.34
PaCO2 65 torr
PaO2 47 torr
HCO3 31 mEq/L
BE +6
She is showing signs of shortness and has inspiratory crackles on auscultation. Which of the following would you recommend for this patient?
A. Nonrebreathing mask at 10 L/min
B. Air-entrainment mask at 28%
C. Albuterol via a small-volume nebulizer
D. Nasal cannula at 4 L/min

31. A 61-year-old male patient is post-abdominal surgery and has been on a high-flow nasal cannula at 20 L/min for three days. The patient’s ABG results are as follows:
pH 7.39
PaCO2 43 torr
PaO2 157 torr
SaO2 99%
HCO3 24 mEq/L
BE +2
Which of the following is the best action to take at this time?
A. Decrease the flow
B. Decrease the FiO2
C. Decrease the flow and FiO2 together
D. Switch to standard nasal cannula

32. A 74 kg male patient is intubated and receiving volume control A/C ventilation with the following settings: FiO2 of 50%, a set rate of 15, and a tidal volume of 550 mL. The patient’s total respiratory rate is 29 breaths/min. His ABG results are as follows:
pH 7.53
PaCO2 27 torr
HCO3 23 mEq/L
BE -2
PaO2 82 torr
SaO2 97%
Which of the following is the best action to take at this time?
A. Increase the FiO2
B. Increase the ventilator rate
C. Increase the tidal volume
D. Add mechanical deadspace

33. A 58-year-old female is receiving volume control A/C ventilation at a rate of 12/min with a tidal volume of 450 mL and an FiO2 of 40%. Her ABG results are as follows:
pH 7.35
PaCO2 44 torr
HCO3 22 mEq/L
BE 0
PaO2 91 torr
SaO2 97%
Based on this information, you should recommend which of the following?
A. Decrease the minute ventilation
B. Discontinue mechanical ventilation
C. Administer IV bicarbonate
D. Maintain the current settings

34. You are monitoring a stable patient that is receiving mechanical ventilation. His ABG results are as follows:
pH 7.49
PaCO2 29 mm Hg
HCO3 24 mEq/L
BE +1
PaO2 87 mm Hg
SaO2 96%
Based on the results, which of the following actions should you take at this time?
A. Add 10 cm H2O PEEP
B. Increase the minute ventilation
C. Decrease the tidal volume
D. Maintain the current settings

35. A patient is intubated and is receiving mechanical ventilation on the pressure control A/C mode at a rate of 10/min and peak pressure of 35 cm H2O. Her ABG results are as follows:
pH 7.31
PaCO2 49 torr
SaO2 96%
HCO3 23 mEq/L
BE -2 mEq/L
Which of the following actions should you take at this time?
A. Increase the FiO2
B. Increase the rate
C. Change the patient to CPAP
D. Make no changes at this time

Final Thoughts

As previously mentioned, respiratory therapists (and students) must be experts on the topic of arterial blood gases. Hopefully, this guide with sample TMC questions can help you prepare for the NBRC board exam.

If you do want to increase your chances of passing the TMC exam on your first (or next) attempt, be sure to check out some of our other helpful resources:

• How to Prepare for (and Pass) the TMC Exam
• TMC Test Bank (Practice Questions)
• Daily Practice Questions via Email
• TMC Bundle Package (Biggest Savings 💰)

You can join thousands of our other previous students who passed both board exams to earn their RRT credentials. Best of luck, and thanks for reading!