NCLEX Practice Test

The nurse is reviewing new arterial blood gas results for a client with an exacerbation of chronic obstructive pulmonary disease. The client's serum pH is 7.45. Which result noted by the nurse is a priority to report to the health care provider?

1. HCO3− of 35 mEq/L (35 mmol/L)

2. Hemoglobin of 19 g/dL (190 g/L)

3. PaCO2 of 67 mm Hg (8.91 kPa)

4. PaO2 of 52 mm Hg (6.92 kPa)

The correct answer is: HCO3− of 35 mEq/L (35 mmol/L)

In this scenario, the most critical result to report is the elevated PaCO2 level of 67 mm Hg. In patients with chronic obstructive pulmonary disease (COPD), an exacerbation often leads to hypoventilation, resulting in increased levels of carbon dioxide. This condition typically causes respiratory acidosis, which may subsequently lead to compensatory metabolic alkalosis, evidenced by a normal or slightly elevated serum pH, as seen here at 7.45. While HCO3− levels may also be elevated due to compensation for chronic respiratory acidosis, the marked increase in PaCO2 indicates significant respiratory distress and potential for respiratory failure. It reflects the inability of the lungs to adequately remove carbon dioxide, which can exacerbate acidosis and lead to serious complications. Although the other results are noteworthy—a high hemoglobin level indicates possible polycythemia related to chronic hypoxia, while a low PaO2 suggests severe hypoxemia—they are not as immediately life-threatening as the elevated PaCO2, which indicates a critical failure in gas exchange that requires urgent intervention. Therefore, the priority is to address the inappropriate elevation of carbon dioxide to improve the client’s respiratory status.