A client with chronic obstructive pulmonary disease (COPD) presented with shortness of breath. Oxygen therapy was started at 2 liters/minute via nasal cannula. The arterial blood gas (ABG) results after treatment were: pH 7.36, PaO, 62 mm Hg, PaCO, 59 mm HG, and HCO, 33 mEq/L (33 mmol/L). Which statement describes the most likely cause of the simultaneous increase in both the PaO, and the PaCO2? Reference Range: PH [7.35 to 7.45] PaCO2 [35 to 45 mm Hg] HCO, [21 to 28 mEq/L (21 to 28 mmol/L)] PaO2 [80 to 100 mm Hg]