NURS 120: Acid-Base Balance Disorders - High Level Assessment (2026
Update) 2026 |WCU
1. A patient presents with arterial blood gas (ABG) results: pH 7.28, PaCO2 55
mmHg, and HCO3 28 mEq/L. Which acid-base imbalance is occurring?
A. Uncompensated Respiratory Acidosis
B. Fully Compensated Respiratory Acidosis
C. Partially Compensated Respiratory Acidosis
D. Partially Compensated Metabolic Acidosis
Answer: C
Rationale: The pH is low (acidosis), the PaCO2 is high (respiratory cause), and the HCO3 is
elevated, indicating the kidneys are attempting to compensate but haven’t returned the pH
to normal yet.
2. Which physiological mechanism is the first line of defense against pH changes
in the extracellular fluid?
A. Renal excretion of hydrogen ions
B. Respiratory rate adjustment
C. Chemical buffer systems
D. Renal reabsorption of bicarbonate
Answer: C
Rationale: Chemical buffers (like bicarbonate, phosphate, and proteins) react within
seconds, making them the first line of defense. Respiratory and renal systems follow.
,3. A patient with prolonged nasogastric (NG) suctioning is most at risk for which
acid-base imbalance?
A. Metabolic Alkalosis
B. Respiratory Alkalosis
C. Metabolic Acidosis
D. Respiratory Acidosis
Answer: A
Rationale: NG suctioning removes gastric hydrochloric acid, leading to a loss of hydrogen
ions and an excess of base, resulting in metabolic alkalosis.
4. What is the expected compensation for a patient in Metabolic Acidosis?
A. Hypoventilation to retain CO2
B. Hyperventilation to blow off CO2
C. Decreased renal reabsorption of HCO3
D. Increased renal excretion of HCO3
Answer: B
Rationale: In metabolic acidosis, the lungs compensate by increasing the rate and depth of
respirations (Kussmaul breathing) to reduce PaCO2 levels.
5. Which clinical finding is specifically associated with High Anion Gap Metabolic
Acidosis?
A. Diabetic Ketoacidosis (DKA)
B. Severe diarrhea
C. Renal Tubular Acidosis
D. Excessive intake of normal saline
Answer: A
Rationale: DKA involves the accumulation of ketoacids (unmeasured anions), which
increases the anion gap. Diarrhea typically results in a normal anion gap metabolic acidosis.
, 6. How does the oxyhemoglobin dissociation curve shift in a patient with acute
Respiratory Acidosis?
A. No shift occurs
B. Shift to the left
C. Shift to the right
D. The curve flattens completely
Answer: C
Rationale: Acidosis and high PaCO2 cause a ‘right shift’ (Bohr effect), decreasing
hemoglobin’s affinity for oxygen and facilitating oxygen unloading to tissues.
7. A patient with COPD has the following ABGs: pH 7.36, PaCO2 58 mmHg, HCO3
32 mEq/L. How should the nurse interpret these results?
A. Fully Compensated Respiratory Acidosis
B. Acute Respiratory Acidosis
C. Partially Compensated Metabolic Alkalosis
D. Chronic Metabolic Acidosis
Answer: A
Rationale: The pH is within the normal range but on the acidic side (7.36). Both PaCO2 and
HCO3 are high, indicating chronic respiratory acidosis that has been fully compensated by
the kidneys.
8. Which electrolyte imbalance is most commonly observed during the initial
phase of Metabolic Acidosis?
A. Hypokalemia
B. Hyperkalemia
C. Hypercalcemia
D. Hyponatremia
Answer: B
Update) 2026 |WCU
1. A patient presents with arterial blood gas (ABG) results: pH 7.28, PaCO2 55
mmHg, and HCO3 28 mEq/L. Which acid-base imbalance is occurring?
A. Uncompensated Respiratory Acidosis
B. Fully Compensated Respiratory Acidosis
C. Partially Compensated Respiratory Acidosis
D. Partially Compensated Metabolic Acidosis
Answer: C
Rationale: The pH is low (acidosis), the PaCO2 is high (respiratory cause), and the HCO3 is
elevated, indicating the kidneys are attempting to compensate but haven’t returned the pH
to normal yet.
2. Which physiological mechanism is the first line of defense against pH changes
in the extracellular fluid?
A. Renal excretion of hydrogen ions
B. Respiratory rate adjustment
C. Chemical buffer systems
D. Renal reabsorption of bicarbonate
Answer: C
Rationale: Chemical buffers (like bicarbonate, phosphate, and proteins) react within
seconds, making them the first line of defense. Respiratory and renal systems follow.
,3. A patient with prolonged nasogastric (NG) suctioning is most at risk for which
acid-base imbalance?
A. Metabolic Alkalosis
B. Respiratory Alkalosis
C. Metabolic Acidosis
D. Respiratory Acidosis
Answer: A
Rationale: NG suctioning removes gastric hydrochloric acid, leading to a loss of hydrogen
ions and an excess of base, resulting in metabolic alkalosis.
4. What is the expected compensation for a patient in Metabolic Acidosis?
A. Hypoventilation to retain CO2
B. Hyperventilation to blow off CO2
C. Decreased renal reabsorption of HCO3
D. Increased renal excretion of HCO3
Answer: B
Rationale: In metabolic acidosis, the lungs compensate by increasing the rate and depth of
respirations (Kussmaul breathing) to reduce PaCO2 levels.
5. Which clinical finding is specifically associated with High Anion Gap Metabolic
Acidosis?
A. Diabetic Ketoacidosis (DKA)
B. Severe diarrhea
C. Renal Tubular Acidosis
D. Excessive intake of normal saline
Answer: A
Rationale: DKA involves the accumulation of ketoacids (unmeasured anions), which
increases the anion gap. Diarrhea typically results in a normal anion gap metabolic acidosis.
, 6. How does the oxyhemoglobin dissociation curve shift in a patient with acute
Respiratory Acidosis?
A. No shift occurs
B. Shift to the left
C. Shift to the right
D. The curve flattens completely
Answer: C
Rationale: Acidosis and high PaCO2 cause a ‘right shift’ (Bohr effect), decreasing
hemoglobin’s affinity for oxygen and facilitating oxygen unloading to tissues.
7. A patient with COPD has the following ABGs: pH 7.36, PaCO2 58 mmHg, HCO3
32 mEq/L. How should the nurse interpret these results?
A. Fully Compensated Respiratory Acidosis
B. Acute Respiratory Acidosis
C. Partially Compensated Metabolic Alkalosis
D. Chronic Metabolic Acidosis
Answer: A
Rationale: The pH is within the normal range but on the acidic side (7.36). Both PaCO2 and
HCO3 are high, indicating chronic respiratory acidosis that has been fully compensated by
the kidneys.
8. Which electrolyte imbalance is most commonly observed during the initial
phase of Metabolic Acidosis?
A. Hypokalemia
B. Hyperkalemia
C. Hypercalcemia
D. Hyponatremia
Answer: B
