A patient with an acute exacerbation of chronic obstructive pulmonary disease (COPD) has an Arterial Blood Gas (ABG) analysis that confirms respiratory acidosis. The nurse anticipates that this acid-base imbalance will most likely cause which corresponding electrolyte disturbance?

1. A

   Hyponatremia

2. B

   Hypercalcemia

3. C

   Hypokalemia

4. D

   Hyperkalemia

Appeared in: NORCET 9 Prelims-2025

Explanation

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• In respiratory acidosis, the body has an excess of hydrogen ions (H+) in the blood.
• To buffer the acid, H+ ions move from the blood into the body's cells.
• To maintain electrical neutrality, potassium (K+) ions shift out of the cells and into the blood.
• This cellular exchange results in an elevated serum potassium level, known as hyperkalemia.
• The patient's condition of acute COPD exacerbation leads to CO2 retention, causing the initial respiratory acidosis.

Why Other Options Were Wrong

• Option A: Hyponatremia (low sodium) is primarily an issue of water and sodium balance, not directly caused by the acid-base shifts seen in respiratory acidosis.
• Option B: Hypercalcemia (high calcium) is not a typical finding in respiratory acidosis. Its causes are usually related to bone metabolism or endocrine disorders.
• Option C: Hypokalemia (low potassium) is the opposite of what occurs in acidosis. It is associated with alkalotic states.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Electrolyte imbalance associated with respiratory acidosis helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Nurses must monitor serum potassium levels closely in patients with acute respiratory acidosis, as hyperkalemia can lead to life-threatening cardiac dysrhythmias.
• Recognizing the link between acidosis and hyperkalemia allows for proactive cardiac monitoring (e.g., placing the patient on a telemetry monitor) and preparation for potential interventions.
• What if? If the patient's ABG showed respiratory alkalosis (e.g., from hyperventilation due to anxiety), the nurse would anticipate the opposite effect: hypokalemia, as potassium would shift into the cells.

How to Approach the Question

• First, identify the primary problem from the question stem: 'acute exacerbation of COPD' leading to 'respiratory acidosis'.
• Recall the body's primary buffering mechanism for acute acidosis.
• Remember the inverse relationship between hydrogen ions (H+) and potassium ions (K+) in terms of their location across the cell membrane during acid-base shifts.
• Visualize the process: Acidosis means high H+ in the blood. To lower blood acidity, H+ moves into cells. To keep the cell's charge balanced, a positive ion must leave. That ion is potassium (K+).
• Conclude that the movement of K+ out of cells into the blood will increase the serum potassium level, leading to hyperkalemia.
• Evaluate the options and eliminate those associated with other conditions (alkalosis, fluid imbalance) to confirm the correct answer.

Concept Tested & Keywords

• Concept Tested: Electrolyte imbalance associated with respiratory acidosis
• Stem keywords: COPD, respiratory acidosis, ABG, electrolyte disturbance
• Lead-in keywords: most likely cause
• Clinical cues: Acute exacerbation of COPD is a key cue for respiratory acidosis due to CO2 retention.

Question ID

QP67QmXB4EROv1hHgAvvPU

Copy ID

Reference Book

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 56-58

E6 Nursing Fundamentals Taylor p. 779-781

E6 Medicine Harrison 22e Part 1 p. 416-418