A nurse reviews ABG results for a client with respiratory acidosis. Which finding is most consistent with this condition?

• A. HCO3- 30 meq/L
• B. PaCO2 50 mmHg
• C. pH 7.45
• D. Potassium 3.3 meq/L

Answer: (C)

When respiration is failing, CO2 accumulates and drives acidemia. The body can compensate by retaining bicarbonate (HCO3-) through the kidneys. In acute respiratory acidosis, pH drops with rising CO2; in chronic cases, the pH may stay near normal because the kidneys have increased bicarbonate to buffer the acid.

Here, the PaCO2 is elevated at 50 mmHg, showing CO2 retention. The bicarbonate is also elevated at 30 mEq/L, indicating renal compensation. The pH is 7.45, which is at the high end of normal or mildly alkalemic, consistent with compensation rather than an ongoing acidemia. Taken together, this pattern points to chronic respiratory acidosis with metabolic compensation. The low potassium is not specific to this pattern and doesn’t define the disorder.