NCLEX Acid-Base Balance and Arterial Blood Gas Interpretation 2 — Questions and Answers
Question 1: A client's ABG shows pH 7.32, PaCO2 48 mm Hg, HCO3 25 mEq/L. How should the nurse interpret these results?
- Partially compensated respiratory acidosis
- Uncompensated respiratory acidosis (Correct answer)
- Uncompensated metabolic acidosis
- Fully compensated respiratory acidosis
Correct answer: Uncompensated respiratory acidosis
Low pH with high PaCO2 and a normal HCO3 means respiratory acidosis with no renal compensation yet.
Question 2: ABG results: pH 7.37, PaCO2 30 mm Hg, HCO3 17 mEq/L. Which interpretation is correct?
- Fully compensated respiratory alkalosis
- Partially compensated metabolic acidosis
- Fully compensated metabolic acidosis (Correct answer)
- Uncompensated respiratory alkalosis
Correct answer: Fully compensated metabolic acidosis
pH is normal but on the acidic side of 7.40, and the low HCO3 matches it, so this is metabolic acidosis fully compensated by a low PaCO2.
Question 3: A client has pH 7.50, PaCO2 47 mm Hg, HCO3 34 mEq/L. What is the interpretation?
- Uncompensated metabolic alkalosis
- Partially compensated respiratory acidosis
- Fully compensated metabolic alkalosis
- Partially compensated metabolic alkalosis (Correct answer)
Correct answer: Partially compensated metabolic alkalosis
High pH and high HCO3 show metabolic alkalosis, and the raised PaCO2 means the lungs are compensating, but pH is still abnormal.
Question 4: ABG results: pH 7.30, PaCO2 55 mm Hg, HCO3 30 mEq/L. How does the nurse classify this?
- Partially compensated respiratory acidosis (Correct answer)
- Partially compensated metabolic alkalosis
- Fully compensated respiratory acidosis
- Uncompensated metabolic acidosis
Correct answer: Partially compensated respiratory acidosis
Acidic pH with high PaCO2 shows respiratory acidosis; the high HCO3 is renal compensation that has not yet normalized the pH.
Question 5: Which statement correctly describes compensation for a primary respiratory acid-base disorder?
- The lungs compensate within minutes
- The kidneys compensate over hours to days (Correct answer)
- The liver compensates by producing bicarbonate within minutes
- The kidneys compensate within minutes
Correct answer: The kidneys compensate over hours to days
Respiratory disorders are compensated by the kidneys retaining or excreting HCO3 and H+, which takes hours to days.
Question 6: A client's ABG shows pH 7.48, PaCO2 30 mm Hg, HCO3 23 mEq/L. What is the interpretation?
- Uncompensated metabolic alkalosis
- Partially compensated respiratory alkalosis
- Uncompensated respiratory alkalosis (Correct answer)
- Fully compensated metabolic acidosis
Correct answer: Uncompensated respiratory alkalosis
High pH with low PaCO2 and a normal HCO3 means respiratory alkalosis with no metabolic compensation.
Question 7: ABG results: pH 7.43, PaCO2 50 mm Hg, HCO3 33 mEq/L. Which interpretation is most accurate?
- Fully compensated metabolic alkalosis (Correct answer)
- Fully compensated respiratory acidosis
- Partially compensated metabolic alkalosis
- Normal ABG
Correct answer: Fully compensated metabolic alkalosis
pH is normal but on the alkaline side of 7.40, so the high HCO3 is the primary problem and the high PaCO2 is full respiratory compensation.
