When the Nurse Is Analyzing the Results of a Patient's

When the nurse is analyzing the results of a patient's arterial blood gases (ABGs) , which finding indicates the need for most immediate action?

A) The arterial oxygen saturation (SaO₂) is 92%.
B) The partial pressure of oxygen in arterial blood (PaO₂) is 59 mm Hg.
C) The partial pressure of CO₂ in arterial blood (PaCO₂) is 31 mm Hg.
D) The bicarbonate level (HCO₃-) is 29 mEq/L.