Comprehensive Examination Guide: HESI Med-Surg I
Exam 2 (2026-2027) 200 Practice Questions Covering
Acid-Base, Electrolytes, Fluids, Neuro & Sensory
Module 1: Acid-Base Balance Fundamentals
Question 1
The nurse is reviewing arterial blood gas (ABG) results: pH 7.32, PaCO2 48 mmHg, HCO3- 24
mEq/L. Which condition does this indicate?
A) Uncompensated respiratory acidosis
B) Uncompensated metabolic acidosis
C) Fully compensated respiratory acidosis
D) Partially compensated metabolic acidosis
Answer: A
Explanation: The pH is below 7.35 (acidosis), PaCO2 is elevated above 45 mmHg (respiratory
cause), and HCO3- is normal (24 mEq/L). Since the HCO3- has not changed to compensate, this
represents uncompensated respiratory acidosis. The kidneys take 24-48 hours to begin
compensating, so this is an acute respiratory acidosis.
Question 2
A client with diabetic ketoacidosis (DKA) has the following ABG results: pH 7.28, PaCO2 30
mmHg, HCO3- 16 mEq/L. The nurse interprets these results as:
A) Uncompensated metabolic acidosis
B) Partially compensated metabolic acidosis
C) Fully compensated metabolic acidosis
D) Uncompensated respiratory acidosis
Answer: B
Explanation: The pH is below 7.35 (acidosis), HCO3- is below 22 mEq/L (metabolic cause), and
PaCO2 is below 35 mmHg (respiratory compensation). Since the pH is not normalized, this
represents partially compensated metabolic acidosis. The lungs are trying to blow off CO2 to
compensate, but the pH remains acidic.
1
,Question 3
A client with chronic obstructive pulmonary disease (COPD) has ABG results: pH 7.36, PaCO2 58
mmHg, HCO3- 32 mEq/L. Which interpretation is correct?
A) Uncompensated respiratory acidosis
B) Partially compensated respiratory acidosis
C) Fully compensated respiratory acidosis
D) Uncompensated metabolic alkalosis
Answer: C
Explanation: The pH is within normal range (7.35-7.45) despite the elevated PaCO2 (respiratory
acidosis) because the kidneys have retained bicarbonate (HCO3- 32 mEq/L) to compensate. This
represents fully compensated respiratory acidosis, commonly seen in chronic COPD patients
who have renal compensation.
Question 4
A client is hyperventilating due to anxiety. The nurse expects which ABG finding?
A) pH 7.50, PaCO2 28 mmHg, HCO3- 24 mEq/L
B) pH 7.30, PaCO2 52 mmHg, HCO3- 24 mEq/L
C) pH 7.35, PaCO2 45 mmHg, HCO3- 28 mEq/L
D) pH 7.45, PaCO2 40 mmHg, HCO3- 24 mEq/L
Answer: A
Explanation: Hyperventilation causes excessive CO2 elimination (PaCO2 < 35 mmHg), leading to
respiratory alkalosis (pH > 7.45). The HCO3- remains normal initially because this is an acute
respiratory process. This is a common finding in anxiety, panic attacks, and early salicylate
toxicity.
Question 5
A client with severe vomiting has ABG results: pH 7.50, PaCO2 44 mmHg, HCO3- 34 mEq/L.
Which condition does this indicate?
A) Uncompensated respiratory alkalosis
B) Uncompensated metabolic alkalosis
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,C) Partially compensated metabolic alkalosis
D) Fully compensated respiratory alkalosis
Answer: B
Explanation: Severe vomiting causes loss of gastric acid (HCl), leading to metabolic alkalosis.
The pH is elevated (>7.45), HCO3- is elevated (>26 mEq/L), and PaCO2 is normal (35-45 mmHg).
Since the PaCO2 is normal, this represents uncompensated metabolic alkalosis.
Question 6
The nurse is caring for a client with salicylate toxicity who is hyperventilating. Which ABG finding
is most consistent with the early stage of this condition?
A) pH 7.48, PaCO2 30 mmHg, HCO3- 22 mEq/L
B) pH 7.30, PaCO2 50 mmHg, HCO3- 28 mEq/L
C) pH 7.38, PaCO2 42 mmHg, HCO3- 24 mEq/L
D) pH 7.42, PaCO2 38 mmHg, HCO3- 26 mEq/L
Answer: A
Explanation: Early salicylate toxicity stimulates the respiratory center, causing hyperventilation
and respiratory alkalosis (pH > 7.45, PaCO2 < 35 mmHg). As toxicity progresses, metabolic
acidosis develops. HCO3- of 22 mEq/L is within normal range, consistent with an acute
respiratory process.
Question 7
A client with renal failure has ABG results: pH 7.30, PaCO2 32 mmHg, HCO3- 18 mEq/L. The
nurse recognizes that the PaCO2 is low because:
A) The kidneys are excreting excess bicarbonate
B) The lungs are compensating by blowing off CO2
C) The client is hypoventilating
D) The kidneys are retaining CO2
Answer: B
Explanation: In metabolic acidosis, the lungs compensate by increasing the rate and depth of
respirations (Kussmaul respirations) to blow off CO2. This lowers PaCO2. The kidneys are unable
to compensate effectively in renal failure because they cannot excrete hydrogen ions or
reabsorb bicarbonate.
3
, Question 8
A client is experiencing respiratory acidosis. Which assessment finding would the nurse expect?
A) Hyperventilation with deep, rapid respirations
B) Hypoventilation with shallow, slow respirations
C) Kussmaul respirations
D) Cheyne-Stokes respirations
Answer: B
Explanation: Respiratory acidosis results from hypoventilation, which causes CO2 retention.
Causes include COPD, sedative overdose, neuromuscular disorders, and chest wall injury.
Hyperventilation (A) would cause respiratory alkalosis. Kussmaul respirations (C) are seen in
metabolic acidosis.
Question 9
The nurse is monitoring a client's ABG results after administering sodium bicarbonate. Which
finding indicates the treatment is effective?
A) pH increasing toward normal
B) PaCO2 increasing
C) HCO3- decreasing
D) pH decreasing
Answer: A
Explanation: Sodium bicarbonate is administered to treat metabolic acidosis by increasing the
serum bicarbonate level, which should raise the pH toward normal. PaCO2 would decrease as
the lungs compensate, and HCO3- would increase, not decrease. If pH continues to decrease,
the treatment is not effective.
Question 10
A client with sepsis has ABG results: pH 7.25, PaCO2 28 mmHg, HCO3- 14 mEq/L. Which
condition does this represent?
A) Uncompensated respiratory acidosis
B) Partially compensated metabolic acidosis
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Exam 2 (2026-2027) 200 Practice Questions Covering
Acid-Base, Electrolytes, Fluids, Neuro & Sensory
Module 1: Acid-Base Balance Fundamentals
Question 1
The nurse is reviewing arterial blood gas (ABG) results: pH 7.32, PaCO2 48 mmHg, HCO3- 24
mEq/L. Which condition does this indicate?
A) Uncompensated respiratory acidosis
B) Uncompensated metabolic acidosis
C) Fully compensated respiratory acidosis
D) Partially compensated metabolic acidosis
Answer: A
Explanation: The pH is below 7.35 (acidosis), PaCO2 is elevated above 45 mmHg (respiratory
cause), and HCO3- is normal (24 mEq/L). Since the HCO3- has not changed to compensate, this
represents uncompensated respiratory acidosis. The kidneys take 24-48 hours to begin
compensating, so this is an acute respiratory acidosis.
Question 2
A client with diabetic ketoacidosis (DKA) has the following ABG results: pH 7.28, PaCO2 30
mmHg, HCO3- 16 mEq/L. The nurse interprets these results as:
A) Uncompensated metabolic acidosis
B) Partially compensated metabolic acidosis
C) Fully compensated metabolic acidosis
D) Uncompensated respiratory acidosis
Answer: B
Explanation: The pH is below 7.35 (acidosis), HCO3- is below 22 mEq/L (metabolic cause), and
PaCO2 is below 35 mmHg (respiratory compensation). Since the pH is not normalized, this
represents partially compensated metabolic acidosis. The lungs are trying to blow off CO2 to
compensate, but the pH remains acidic.
1
,Question 3
A client with chronic obstructive pulmonary disease (COPD) has ABG results: pH 7.36, PaCO2 58
mmHg, HCO3- 32 mEq/L. Which interpretation is correct?
A) Uncompensated respiratory acidosis
B) Partially compensated respiratory acidosis
C) Fully compensated respiratory acidosis
D) Uncompensated metabolic alkalosis
Answer: C
Explanation: The pH is within normal range (7.35-7.45) despite the elevated PaCO2 (respiratory
acidosis) because the kidneys have retained bicarbonate (HCO3- 32 mEq/L) to compensate. This
represents fully compensated respiratory acidosis, commonly seen in chronic COPD patients
who have renal compensation.
Question 4
A client is hyperventilating due to anxiety. The nurse expects which ABG finding?
A) pH 7.50, PaCO2 28 mmHg, HCO3- 24 mEq/L
B) pH 7.30, PaCO2 52 mmHg, HCO3- 24 mEq/L
C) pH 7.35, PaCO2 45 mmHg, HCO3- 28 mEq/L
D) pH 7.45, PaCO2 40 mmHg, HCO3- 24 mEq/L
Answer: A
Explanation: Hyperventilation causes excessive CO2 elimination (PaCO2 < 35 mmHg), leading to
respiratory alkalosis (pH > 7.45). The HCO3- remains normal initially because this is an acute
respiratory process. This is a common finding in anxiety, panic attacks, and early salicylate
toxicity.
Question 5
A client with severe vomiting has ABG results: pH 7.50, PaCO2 44 mmHg, HCO3- 34 mEq/L.
Which condition does this indicate?
A) Uncompensated respiratory alkalosis
B) Uncompensated metabolic alkalosis
2
,C) Partially compensated metabolic alkalosis
D) Fully compensated respiratory alkalosis
Answer: B
Explanation: Severe vomiting causes loss of gastric acid (HCl), leading to metabolic alkalosis.
The pH is elevated (>7.45), HCO3- is elevated (>26 mEq/L), and PaCO2 is normal (35-45 mmHg).
Since the PaCO2 is normal, this represents uncompensated metabolic alkalosis.
Question 6
The nurse is caring for a client with salicylate toxicity who is hyperventilating. Which ABG finding
is most consistent with the early stage of this condition?
A) pH 7.48, PaCO2 30 mmHg, HCO3- 22 mEq/L
B) pH 7.30, PaCO2 50 mmHg, HCO3- 28 mEq/L
C) pH 7.38, PaCO2 42 mmHg, HCO3- 24 mEq/L
D) pH 7.42, PaCO2 38 mmHg, HCO3- 26 mEq/L
Answer: A
Explanation: Early salicylate toxicity stimulates the respiratory center, causing hyperventilation
and respiratory alkalosis (pH > 7.45, PaCO2 < 35 mmHg). As toxicity progresses, metabolic
acidosis develops. HCO3- of 22 mEq/L is within normal range, consistent with an acute
respiratory process.
Question 7
A client with renal failure has ABG results: pH 7.30, PaCO2 32 mmHg, HCO3- 18 mEq/L. The
nurse recognizes that the PaCO2 is low because:
A) The kidneys are excreting excess bicarbonate
B) The lungs are compensating by blowing off CO2
C) The client is hypoventilating
D) The kidneys are retaining CO2
Answer: B
Explanation: In metabolic acidosis, the lungs compensate by increasing the rate and depth of
respirations (Kussmaul respirations) to blow off CO2. This lowers PaCO2. The kidneys are unable
to compensate effectively in renal failure because they cannot excrete hydrogen ions or
reabsorb bicarbonate.
3
, Question 8
A client is experiencing respiratory acidosis. Which assessment finding would the nurse expect?
A) Hyperventilation with deep, rapid respirations
B) Hypoventilation with shallow, slow respirations
C) Kussmaul respirations
D) Cheyne-Stokes respirations
Answer: B
Explanation: Respiratory acidosis results from hypoventilation, which causes CO2 retention.
Causes include COPD, sedative overdose, neuromuscular disorders, and chest wall injury.
Hyperventilation (A) would cause respiratory alkalosis. Kussmaul respirations (C) are seen in
metabolic acidosis.
Question 9
The nurse is monitoring a client's ABG results after administering sodium bicarbonate. Which
finding indicates the treatment is effective?
A) pH increasing toward normal
B) PaCO2 increasing
C) HCO3- decreasing
D) pH decreasing
Answer: A
Explanation: Sodium bicarbonate is administered to treat metabolic acidosis by increasing the
serum bicarbonate level, which should raise the pH toward normal. PaCO2 would decrease as
the lungs compensate, and HCO3- would increase, not decrease. If pH continues to decrease,
the treatment is not effective.
Question 10
A client with sepsis has ABG results: pH 7.25, PaCO2 28 mmHg, HCO3- 14 mEq/L. Which
condition does this represent?
A) Uncompensated respiratory acidosis
B) Partially compensated metabolic acidosis
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