A nurse is reviewing ABG results for a client who has COPD. Which of the following findings should the nurse expect?

Arterial blood gas interpretation in a client with Chronic obstructive pulmonary disease focuses on identifying chronic respiratory changes due to long-standing impaired ventilation and gas exchange. COPD is characterized by airflow obstruction that leads to CO₂ retention and varying degrees of hypoxemia. Over time, the kidneys may compensate for chronic respiratory acidosis by retaining bicarbonate. Understanding expected ABG patterns helps distinguish compensated from acute respiratory failure states. Rationale: A. A pH of 7.38 is within the normal range and may indicate full compensation, but it does not specifically reflect the expected primary abnormality in COPD. In COPD, the key abnormality is typically elevated PaCO₂ with possible renal compensation affecting pH. Therefore, pH alone is not the most characteristic finding. B. A PaCO₂ of 48 mm Hg is an expected finding in COPD due to impaired alveolar ventilation and CO₂ retention. Chronic airway obstruction leads to reduced gas exchange efficiency, resulting in elevated carbon dioxide levels in the blood. This reflects the respiratory component of the disorder and is a hallmark ABG change in COPD. C. A bicarbonate level of 25 mEq/L is within normal range and does not strongly reflect the chronic compensatory changes often seen in COPD. In long-standing disease, HCO₃⁻ is typically elevated as the kidneys retain bicarbonate to buffer chronic respiratory acidosis. Therefore, this value does not best represent expected COPD compensation. D. A PaO₂ of 85 mm Hg is within normal limits and does not reflect the typical oxygenation impairment seen in many COPD clients. While some individuals may maintain near-normal oxygen levels, COPD is often associated with varying degrees of hypoxemia. The more consistent abnormality is elevated PaCO₂ rather than normal oxygen tension.