NSG 320 Adult Health Nursing I — Exam 3
Comprehensive Assessment: Respiratory
Disorders, ABG Interpretation, Mechanical
Ventilation & Critical Care
Question 1 (MC — ABG Interpretation)
A 68-year-old male with COPD presents with increased dyspnea. ABG results: pH 7.32, PaCO₂ 58
mmHg, HCO₃⁻ 30 mEq/L, PaO₂ 62 mmHg. Using the ROME method, the nurse identifies which
acid-base disorder?
A. Uncompensated respiratory acidosis
B. Partially compensated respiratory acidosis
C. Fully compensated metabolic alkalosis
D. Partially compensated metabolic acidosis
[CORRECT: B]
Rationale: Using ROME: pH 7.32 (acidotic) and PaCO₂ 58 (elevated/acidic) move in opposite
directions → respiratory origin. HCO₃⁻ 30 is elevated (alkalotic) but pH remains abnormal at
7.32, indicating the kidneys have begun compensating but have not fully normalized the pH.
This is partially compensated respiratory acidosis. In COPD, chronic CO₂ retention drives renal
bicarbonate retention. The elevated HCO₃⁻ represents metabolic compensation, but because pH
is still outside normal range (7.35-7.45), compensation is incomplete. Full compensation would
show pH within normal limits (typically 7.35-7.39) with both PaCO₂ and HCO₃⁻ abnormal.
Question 2 (MC — ABG Interpretation)
A 24-year-old patient with diabetic ketoacidosis has the following ABG: pH 7.28, PaCO₂ 22
mmHg, HCO₃⁻ 14 mEq/L, PaO₂ 95 mmHg. What is the appropriate interpretation?
A. Uncompensated metabolic acidosis
B. Partially compensated metabolic acidosis
C. Fully compensated respiratory alkalosis
D. Combined metabolic and respiratory acidosis
[CORRECT: B]
,Rationale: ROME analysis: pH 7.28 (acidotic) and HCO₃⁻ 14 (low/acidotic) move in the same
direction → metabolic origin. PaCO₂ 22 is decreased (alkalotic), representing hyperventilation as
respiratory compensation. Because pH remains abnormal at 7.28, this is partially compensated
metabolic acidosis. In DKA, accumulated ketones consume bicarbonate (metabolic acidosis),
triggering Kussmaul respirations to blow off CO₂. The decreased PaCO₂ demonstrates the
respiratory system's attempt to compensate, but the pH has not returned to the normal range,
confirming partial rather than full compensation. Full compensation would require pH 7.35-
7.39.
Question 3 (SATA — ABG Interpretation)
A patient with severe vomiting for 3 days has ABG: pH 7.50, PaCO₂ 48 mmHg, HCO₃⁻ 36 mEq/L.
Which statements by the nurse indicate correct understanding of this ABG? Select all that
apply.
A. The primary disorder is metabolic alkalosis
B. The PaCO₂ elevation represents respiratory compensation
C. This is an example of fully compensated metabolic alkalosis
D. The pH and HCO₃⁻ move in the same direction, confirming metabolic origin
E. The elevated PaCO₂ indicates a concurrent respiratory acidosis
F. If this were fully compensated, the pH would be between 7.35 and 7.45
[CORRECT: A, B, D, F]
Rationale: pH 7.50 (alkalotic) and HCO₃⁻ 36 (elevated/alkalotic) move in the same direction →
metabolic alkalosis (A, D correct). PaCO₂ 48 is elevated as the respiratory system retains CO₂ to
compensate for the alkalosis (B correct). Because pH is still abnormal at 7.50, this is partially
compensated, not fully compensated (C incorrect). The elevated PaCO₂ is compensatory, not a
primary respiratory acidosis (E incorrect). Full compensation would show pH within normal
range with both values abnormal (F correct). Prolonged vomiting causes loss of gastric acid
(HCl), leading to metabolic alkalosis; the respiratory system compensates by hypoventilating to
retain CO₂.
Question 4 (Calculation-Based — ABG Interpretation)
A patient with acute-on-chronic respiratory failure has ABG: pH 7.37, PaCO₂ 58 mmHg, HCO₃⁻ 33
mEq/L, PaO₂ 68 mmHg. The nurse should document which acid-base status?
,A. Fully compensated respiratory acidosis
B. Fully compensated metabolic alkalosis
C. Partially compensated respiratory acidosis
D. Normal ABG
[CORRECT: A]
Rationale: pH 7.37 is within normal range (7.35-7.45) but on the acidotic side. PaCO₂ 58 is
elevated (respiratory acidosis), and HCO₃⁻ 33 is elevated (metabolic alkalosis/compensation).
Using ROME: pH and PaCO₂ move in opposite directions if we consider the underlying disorder.
The pH is normal despite both values being abnormal, indicating full compensation. The
primary disorder is respiratory acidosis (elevated PaCO₂ drives the acidosis), with renal
compensation (elevated HCO₃⁻) having successfully returned pH to normal. This pattern is
classic in chronic COPD where renal compensation has had time to fully adjust. The nurse must
recognize that "normal" pH with abnormal PaCO₂ and HCO₃⁻ always indicates full compensation,
not a normal ABG.
Question 5 (MC — ABG Interpretation)
A trauma patient has ABG: pH 7.18, PaCO₂ 28 mmHg, HCO₃⁻ 10 mEq/L, PaO₂ 88 mmHg, lactate
6.2 mmol/L. Which interpretation is correct?
A. Partially compensated metabolic acidosis with adequate oxygenation
B. Uncompensated metabolic acidosis with concurrent respiratory alkalosis
C. Partially compensated metabolic acidosis with anion gap elevation
D. Combined respiratory and metabolic acidosis
[CORRECT: C]
Rationale: pH 7.18 and HCO₃⁻ 10 move in the same direction → metabolic acidosis. PaCO₂ 28 is
decreased, indicating respiratory compensation (Kussmaul breathing in shock). Because pH
remains severely abnormal, this is partially compensated metabolic acidosis. The elevated
lactate (6.2 mmol/L; normal <2.0) indicates lactic acidosis from tissue hypoperfusion. Anion gap
= Na⁺ − (Cl⁻ + HCO₃⁻); with HCO₃⁻ this low, the anion gap is elevated, confirming a high-anion-
gap metabolic acidosis. The PaO₂ of 88 mmHg is acceptable but does not reflect tissue
oxygenation status—lactate is the better indicator of perfusion. This pattern is classic in
hemorrhagic shock where tissue hypoxia generates lactic acid, consuming bicarbonate.
Sub-Topic 1.2: Oxygen Delivery Devices (3 Questions)
, Question 6 (MC — Oxygen Delivery)
A patient with COPD exacerbation has a SpO₂ of 84% on room air. The provider orders oxygen
titration to maintain SpO₂ 88-92%. Which delivery device should the nurse select to achieve
precise, controlled low-flow oxygen?
A. Simple face mask at 5 L/min
B. Nasal cannula at 2 L/min
C. Venturi mask at 24% FiO₂
D. Non-rebreather mask at 10 L/min
[CORRECT: C]
Rationale: The Venturi mask delivers the most precise, controlled FiO₂ (24-50%) regardless of
the patient's breathing pattern, making it ideal for COPD patients who are CO₂ retainers and
require careful titration to avoid suppressing hypoxic drive. The Venturi mechanism entrains
room air through specific port sizes to achieve exact oxygen concentrations. Nasal cannula (B)
delivers variable FiO₂ (approximately 24-44% at 1-6 L/min) depending on inspiratory flow rate
and breathing pattern. Simple mask (A) delivers 35-50% but is not precise. Non-rebreather (D)
delivers 60-90% and would be dangerous for a CO₂ retainer, potentially causing CO₂ narcosis by
removing the hypoxic stimulus to breathe. The target SpO₂ of 88-92% reflects the need to
balance oxygenation with preservation of hypoxic drive.
Question 7 (SATA — Oxygen Delivery)
A nurse is caring for a patient with acute hypoxemic respiratory failure (PaO₂ 54 mmHg) who
requires high-flow oxygen. Which statements about high-flow nasal cannula (HFNC) are correct?
Select all that apply.
A. HFNC can deliver up to 100% FiO₂ with flow rates up to 60 L/min
B. The high flow rates provide low-level positive end-expiratory pressure (PEEP)
C. HFNC is contraindicated in patients with facial trauma or basal skull fractures
D. HFNC reduces anatomical dead space by flushing CO₂ from the upper airway
E. HFNC requires a tightly sealed mask to prevent room air entrainment
F. HFNC improves mucociliary clearance through warmed, humidified gas
[CORRECT: A, B, D, F]
Rationale: HFNC delivers heated, humidified oxygen at flow rates of 20-60 L/min with FiO₂ up to
100% (A correct). The high flow generates approximately 2-6 cm H₂O of positive pressure,
Comprehensive Assessment: Respiratory
Disorders, ABG Interpretation, Mechanical
Ventilation & Critical Care
Question 1 (MC — ABG Interpretation)
A 68-year-old male with COPD presents with increased dyspnea. ABG results: pH 7.32, PaCO₂ 58
mmHg, HCO₃⁻ 30 mEq/L, PaO₂ 62 mmHg. Using the ROME method, the nurse identifies which
acid-base disorder?
A. Uncompensated respiratory acidosis
B. Partially compensated respiratory acidosis
C. Fully compensated metabolic alkalosis
D. Partially compensated metabolic acidosis
[CORRECT: B]
Rationale: Using ROME: pH 7.32 (acidotic) and PaCO₂ 58 (elevated/acidic) move in opposite
directions → respiratory origin. HCO₃⁻ 30 is elevated (alkalotic) but pH remains abnormal at
7.32, indicating the kidneys have begun compensating but have not fully normalized the pH.
This is partially compensated respiratory acidosis. In COPD, chronic CO₂ retention drives renal
bicarbonate retention. The elevated HCO₃⁻ represents metabolic compensation, but because pH
is still outside normal range (7.35-7.45), compensation is incomplete. Full compensation would
show pH within normal limits (typically 7.35-7.39) with both PaCO₂ and HCO₃⁻ abnormal.
Question 2 (MC — ABG Interpretation)
A 24-year-old patient with diabetic ketoacidosis has the following ABG: pH 7.28, PaCO₂ 22
mmHg, HCO₃⁻ 14 mEq/L, PaO₂ 95 mmHg. What is the appropriate interpretation?
A. Uncompensated metabolic acidosis
B. Partially compensated metabolic acidosis
C. Fully compensated respiratory alkalosis
D. Combined metabolic and respiratory acidosis
[CORRECT: B]
,Rationale: ROME analysis: pH 7.28 (acidotic) and HCO₃⁻ 14 (low/acidotic) move in the same
direction → metabolic origin. PaCO₂ 22 is decreased (alkalotic), representing hyperventilation as
respiratory compensation. Because pH remains abnormal at 7.28, this is partially compensated
metabolic acidosis. In DKA, accumulated ketones consume bicarbonate (metabolic acidosis),
triggering Kussmaul respirations to blow off CO₂. The decreased PaCO₂ demonstrates the
respiratory system's attempt to compensate, but the pH has not returned to the normal range,
confirming partial rather than full compensation. Full compensation would require pH 7.35-
7.39.
Question 3 (SATA — ABG Interpretation)
A patient with severe vomiting for 3 days has ABG: pH 7.50, PaCO₂ 48 mmHg, HCO₃⁻ 36 mEq/L.
Which statements by the nurse indicate correct understanding of this ABG? Select all that
apply.
A. The primary disorder is metabolic alkalosis
B. The PaCO₂ elevation represents respiratory compensation
C. This is an example of fully compensated metabolic alkalosis
D. The pH and HCO₃⁻ move in the same direction, confirming metabolic origin
E. The elevated PaCO₂ indicates a concurrent respiratory acidosis
F. If this were fully compensated, the pH would be between 7.35 and 7.45
[CORRECT: A, B, D, F]
Rationale: pH 7.50 (alkalotic) and HCO₃⁻ 36 (elevated/alkalotic) move in the same direction →
metabolic alkalosis (A, D correct). PaCO₂ 48 is elevated as the respiratory system retains CO₂ to
compensate for the alkalosis (B correct). Because pH is still abnormal at 7.50, this is partially
compensated, not fully compensated (C incorrect). The elevated PaCO₂ is compensatory, not a
primary respiratory acidosis (E incorrect). Full compensation would show pH within normal
range with both values abnormal (F correct). Prolonged vomiting causes loss of gastric acid
(HCl), leading to metabolic alkalosis; the respiratory system compensates by hypoventilating to
retain CO₂.
Question 4 (Calculation-Based — ABG Interpretation)
A patient with acute-on-chronic respiratory failure has ABG: pH 7.37, PaCO₂ 58 mmHg, HCO₃⁻ 33
mEq/L, PaO₂ 68 mmHg. The nurse should document which acid-base status?
,A. Fully compensated respiratory acidosis
B. Fully compensated metabolic alkalosis
C. Partially compensated respiratory acidosis
D. Normal ABG
[CORRECT: A]
Rationale: pH 7.37 is within normal range (7.35-7.45) but on the acidotic side. PaCO₂ 58 is
elevated (respiratory acidosis), and HCO₃⁻ 33 is elevated (metabolic alkalosis/compensation).
Using ROME: pH and PaCO₂ move in opposite directions if we consider the underlying disorder.
The pH is normal despite both values being abnormal, indicating full compensation. The
primary disorder is respiratory acidosis (elevated PaCO₂ drives the acidosis), with renal
compensation (elevated HCO₃⁻) having successfully returned pH to normal. This pattern is
classic in chronic COPD where renal compensation has had time to fully adjust. The nurse must
recognize that "normal" pH with abnormal PaCO₂ and HCO₃⁻ always indicates full compensation,
not a normal ABG.
Question 5 (MC — ABG Interpretation)
A trauma patient has ABG: pH 7.18, PaCO₂ 28 mmHg, HCO₃⁻ 10 mEq/L, PaO₂ 88 mmHg, lactate
6.2 mmol/L. Which interpretation is correct?
A. Partially compensated metabolic acidosis with adequate oxygenation
B. Uncompensated metabolic acidosis with concurrent respiratory alkalosis
C. Partially compensated metabolic acidosis with anion gap elevation
D. Combined respiratory and metabolic acidosis
[CORRECT: C]
Rationale: pH 7.18 and HCO₃⁻ 10 move in the same direction → metabolic acidosis. PaCO₂ 28 is
decreased, indicating respiratory compensation (Kussmaul breathing in shock). Because pH
remains severely abnormal, this is partially compensated metabolic acidosis. The elevated
lactate (6.2 mmol/L; normal <2.0) indicates lactic acidosis from tissue hypoperfusion. Anion gap
= Na⁺ − (Cl⁻ + HCO₃⁻); with HCO₃⁻ this low, the anion gap is elevated, confirming a high-anion-
gap metabolic acidosis. The PaO₂ of 88 mmHg is acceptable but does not reflect tissue
oxygenation status—lactate is the better indicator of perfusion. This pattern is classic in
hemorrhagic shock where tissue hypoxia generates lactic acid, consuming bicarbonate.
Sub-Topic 1.2: Oxygen Delivery Devices (3 Questions)
, Question 6 (MC — Oxygen Delivery)
A patient with COPD exacerbation has a SpO₂ of 84% on room air. The provider orders oxygen
titration to maintain SpO₂ 88-92%. Which delivery device should the nurse select to achieve
precise, controlled low-flow oxygen?
A. Simple face mask at 5 L/min
B. Nasal cannula at 2 L/min
C. Venturi mask at 24% FiO₂
D. Non-rebreather mask at 10 L/min
[CORRECT: C]
Rationale: The Venturi mask delivers the most precise, controlled FiO₂ (24-50%) regardless of
the patient's breathing pattern, making it ideal for COPD patients who are CO₂ retainers and
require careful titration to avoid suppressing hypoxic drive. The Venturi mechanism entrains
room air through specific port sizes to achieve exact oxygen concentrations. Nasal cannula (B)
delivers variable FiO₂ (approximately 24-44% at 1-6 L/min) depending on inspiratory flow rate
and breathing pattern. Simple mask (A) delivers 35-50% but is not precise. Non-rebreather (D)
delivers 60-90% and would be dangerous for a CO₂ retainer, potentially causing CO₂ narcosis by
removing the hypoxic stimulus to breathe. The target SpO₂ of 88-92% reflects the need to
balance oxygenation with preservation of hypoxic drive.
Question 7 (SATA — Oxygen Delivery)
A nurse is caring for a patient with acute hypoxemic respiratory failure (PaO₂ 54 mmHg) who
requires high-flow oxygen. Which statements about high-flow nasal cannula (HFNC) are correct?
Select all that apply.
A. HFNC can deliver up to 100% FiO₂ with flow rates up to 60 L/min
B. The high flow rates provide low-level positive end-expiratory pressure (PEEP)
C. HFNC is contraindicated in patients with facial trauma or basal skull fractures
D. HFNC reduces anatomical dead space by flushing CO₂ from the upper airway
E. HFNC requires a tightly sealed mask to prevent room air entrainment
F. HFNC improves mucociliary clearance through warmed, humidified gas
[CORRECT: A, B, D, F]
Rationale: HFNC delivers heated, humidified oxygen at flow rates of 20-60 L/min with FiO₂ up to
100% (A correct). The high flow generates approximately 2-6 cm H₂O of positive pressure,
