NURS 120 | Acid-Base Balance Disorders | 2026/2027 Update WCU
1. A patient’s ABG results are pH 7.25, PaCO2 50 mmHg, and HCO3 24 mEq/L.
Which acid-base imbalance is present?
A. Metabolic Alkalosis
B. Metabolic Acidosis
C. Respiratory Alkalosis
D. Respiratory Acidosis
Answer: D
Rationale: The pH is low (acidosis), the PaCO2 is high (respiratory component), and the
HCO3 is normal, indicating uncompensated respiratory acidosis.
2. Which clinical condition is most likely to lead to metabolic alkalosis?
A. Severe diarrhea
B. Salicylate overdose
C. Renal failure
D. Prolonged vomiting or NG suctioning
Answer: D
Rationale: Loss of gastric acid through vomiting or NG suctioning leads to a loss of
hydrogen ions, resulting in metabolic alkalosis.
,3. A patient with a pH of 7.48, PaCO2 of 30 mmHg, and HCO3 of 20 mEq/L is
showing which type of compensation?
A. Uncompensated respiratory alkalosis
B. Fully compensated metabolic acidosis
C. Partially compensated metabolic alkalosis
D. Partially compensated respiratory alkalosis
Answer: D
Rationale: The pH is alkaline, PaCO2 is low (respiratory), and the HCO3 is low
(compensatory metabolic attempt), but pH is not back to normal, indicating partial
compensation.
4. What is the primary compensation mechanism for metabolic acidosis?
A. Lungs increasing the rate and depth of respirations
B. Kidneys retaining bicarbonate
C. Lungs decreasing the respiratory rate
D. Kidneys excreting hydrogen ions
Answer: A
Rationale: The lungs compensate for metabolic acidosis by blowing off excess CO2 through
Kussmaul respirations (hyperventilation).
5. Calculate the anion gap given the following: Sodium 140 mEq/L, Chloride 105
mEq/L, Bicarbonate 20 mEq/L.
A. 10 mEq/L
B. 35 mEq/L
C. 25 mEq/L
D. 15 mEq/L
Answer: D
Rationale: Anion Gap = Sodium - (Chloride + Bicarbonate). 140 - (105 + 20) = 15 mEq/L.
, 6. In a patient with chronic COPD, which ABG finding suggests fully
compensated respiratory acidosis?
A. pH 7.28, PaCO2 60, HCO3 26
B. pH 7.36, PaCO2 55, HCO3 32
C. pH 7.46, PaCO2 35, HCO3 24
D. pH 7.31, PaCO2 40, HCO3 20
Answer: B
Rationale: Full compensation means the pH is within the normal range (7.35-7.45) but
slightly on the acidic side, while PaCO2 and HCO3 remain abnormal.
7. Which electrolyte imbalance is most commonly associated with metabolic
acidosis?
A. Hypokalemia
B. Hyponatremia
C. Hyperkalemia
D. Hypocalcemia
Answer: C
Rationale: In acidosis, hydrogen ions move into the cells and potassium moves out to
maintain electrical neutrality, leading to hyperkalemia.
8. A patient is hyperventilating due to extreme anxiety. Which ABG result
should the nurse expect?
A. pH 7.30, PaCO2 50
B. pH 7.35, PaCO2 40
C. pH 7.50, PaCO2 25
D. pH 7.45, PaCO2 45
Answer: C
Rationale: Hyperventilation causes excessive loss of CO2, leading to respiratory alkalosis
(high pH, low PaCO2).
1. A patient’s ABG results are pH 7.25, PaCO2 50 mmHg, and HCO3 24 mEq/L.
Which acid-base imbalance is present?
A. Metabolic Alkalosis
B. Metabolic Acidosis
C. Respiratory Alkalosis
D. Respiratory Acidosis
Answer: D
Rationale: The pH is low (acidosis), the PaCO2 is high (respiratory component), and the
HCO3 is normal, indicating uncompensated respiratory acidosis.
2. Which clinical condition is most likely to lead to metabolic alkalosis?
A. Severe diarrhea
B. Salicylate overdose
C. Renal failure
D. Prolonged vomiting or NG suctioning
Answer: D
Rationale: Loss of gastric acid through vomiting or NG suctioning leads to a loss of
hydrogen ions, resulting in metabolic alkalosis.
,3. A patient with a pH of 7.48, PaCO2 of 30 mmHg, and HCO3 of 20 mEq/L is
showing which type of compensation?
A. Uncompensated respiratory alkalosis
B. Fully compensated metabolic acidosis
C. Partially compensated metabolic alkalosis
D. Partially compensated respiratory alkalosis
Answer: D
Rationale: The pH is alkaline, PaCO2 is low (respiratory), and the HCO3 is low
(compensatory metabolic attempt), but pH is not back to normal, indicating partial
compensation.
4. What is the primary compensation mechanism for metabolic acidosis?
A. Lungs increasing the rate and depth of respirations
B. Kidneys retaining bicarbonate
C. Lungs decreasing the respiratory rate
D. Kidneys excreting hydrogen ions
Answer: A
Rationale: The lungs compensate for metabolic acidosis by blowing off excess CO2 through
Kussmaul respirations (hyperventilation).
5. Calculate the anion gap given the following: Sodium 140 mEq/L, Chloride 105
mEq/L, Bicarbonate 20 mEq/L.
A. 10 mEq/L
B. 35 mEq/L
C. 25 mEq/L
D. 15 mEq/L
Answer: D
Rationale: Anion Gap = Sodium - (Chloride + Bicarbonate). 140 - (105 + 20) = 15 mEq/L.
, 6. In a patient with chronic COPD, which ABG finding suggests fully
compensated respiratory acidosis?
A. pH 7.28, PaCO2 60, HCO3 26
B. pH 7.36, PaCO2 55, HCO3 32
C. pH 7.46, PaCO2 35, HCO3 24
D. pH 7.31, PaCO2 40, HCO3 20
Answer: B
Rationale: Full compensation means the pH is within the normal range (7.35-7.45) but
slightly on the acidic side, while PaCO2 and HCO3 remain abnormal.
7. Which electrolyte imbalance is most commonly associated with metabolic
acidosis?
A. Hypokalemia
B. Hyponatremia
C. Hyperkalemia
D. Hypocalcemia
Answer: C
Rationale: In acidosis, hydrogen ions move into the cells and potassium moves out to
maintain electrical neutrality, leading to hyperkalemia.
8. A patient is hyperventilating due to extreme anxiety. Which ABG result
should the nurse expect?
A. pH 7.30, PaCO2 50
B. pH 7.35, PaCO2 40
C. pH 7.50, PaCO2 25
D. pH 7.45, PaCO2 45
Answer: C
Rationale: Hyperventilation causes excessive loss of CO2, leading to respiratory alkalosis
(high pH, low PaCO2).
