Which condition is defined by inadequate gas exchange causing abnormal arterial oxygen or carbon dioxide levels?

• A. Respiratory Distress
• B. Respiratory Failure
• C. Respiratory Arrest
• D. Apnea

Answer: (B)

Inadequate gas exchange means the body isn’t able to oxygenate the blood or remove carbon dioxide effectively. When this happens, arterial oxygen levels fall and/or arterial carbon dioxide levels rise. That state is respiratory failure—the point at which breathing no longer sustains the body's metabolic needs, so values like PaO2 become low and PaCO2 becomes high. Patients may show fatigue, confusion, cyanosis, or changes in breathing despite effort, and blood gases would reflect hypoxemia and/or hypercapnia. Respiratory distress involves breathing difficulty but still effective gas exchange at first; respiratory arrest or apnea means breathing stops entirely, with no gas exchange occurring. The description given matches respiratory failure because it centers on a lapse in maintaining adequate oxygenation and ventilation leading to abnormal arterial gas levels.