Advanced Patient Assessment Practice Exam

In a patient with COPD, which gas exchange abnormality is most commonly observed?

1. Respiratory alkalosis

2. Metabolic acidosis

3. Respiratory acidosis

4. Normal respiration rates

The correct answer is: Respiratory acidosis

In patients with Chronic Obstructive Pulmonary Disease (COPD), respiratory acidosis is the most commonly observed gas exchange abnormality. This condition arises primarily due to the retention of carbon dioxide (CO2) as airflow becomes restricted and gas exchange is impaired. In obstructive lung diseases like COPD, patients often have difficulty expelling CO2, which leads to increased levels of this gas in the blood. As CO2 accumulates, it reacts with water in the body to form carbonic acid, which subsequently dissociates into bicarbonate and hydrogen ions, lowering the pH of the blood. This shift in the acid-base balance results in respiratory acidosis, characterized by a decrease in blood pH (acidosis) and an increase in arterial carbon dioxide levels. It's important to note that patients with COPD can sometimes demonstrate compensatory mechanisms, leading to a relative balance in severe cases, but the pathological foundation of the disease still predisposes them to chronic respiratory acidosis. Therefore, recognizing this common abnormality is vital for effective diagnosis and management of patients with COPD.