NCLEX-PN® ExaminationReduction of Risk PotentialMedium
A licensed practical nurse (LPN) is reviewing the arterial blood gas (ABG) results for a client with chronic obstructive pulmonary disease (COPD). The results are: pH 7.32, PaCO2 55 mmHg, HCO3 28 mEq/L, PaO2 78 mmHg. Which acid-base imbalance does this indicate?
- ARespiratory alkalosis, uncompensated
- BRespiratory acidosis, partially compensated
- CMetabolic alkalosis
- DMetabolic acidosis
Show answer & explanationAnswer & explanation
Correct answer: B. Respiratory acidosis, partially compensated
The pH of 7.32 indicates acidosis. The elevated PaCO2 (normal 35-45 mmHg) indicates a respiratory cause. The elevated HCO3 (normal 22-26 mEq/L) suggests renal compensation, making it partially compensated.
Why the other options are wrong
- A. Respiratory alkalosis would show a high pH and low PaCO2.
- C. Metabolic alkalosis would show a high pH and high HCO3.
- D. Metabolic acidosis would show a low pH and low HCO3.
ABG Interpretation
Systematic analysis of arterial blood gas values (pH, PaCO2, HCO3) to determine acid-base status and compensation.
- pH indicates acidosis (<7.35) or alkalosis (>7.45).
- PaCO2 reflects respiratory component (acidic if high, alkaline if low).
- HCO3 reflects metabolic component (acidic if low, alkaline if high).
Memory trick: pH: 'Power' (acid/base); PaCO2: 'Puffs' (lungs); HCO3: 'Hydration' (kidneys)