🩺 Nursing Question of the Day

Challenge yourself with one exam-style nursing question every day.

✅ Think carefully • ✅ Choose your answer • ✅ Then scroll down to check the explanation.

🫁 COPD and High-Flow Oxygen Therapy

✅ Answer: (C) Increased PaCO₂

📖 What is COPD?

Chronic = Long-term
Obstructive = Airflow blockage
Pulmonary Disease = Lung disease

👉 COPD is a chronic lung disease (mainly chronic bronchitis and emphysema) that causes persistent airflow limitation and difficulty in breathing.

📖 What is PaCO₂?

PaCO₂ = Partial Pressure of Carbon Dioxide in Arterial Blood.

👉 Normal value: 35–45 mmHg

An increased PaCO₂ indicates carbon dioxide retention (hypercapnia).

🩺 Why is Option (C) Correct?

Some patients with severe COPD have chronic CO₂ retention and rely partly on low oxygen levels (hypoxic drive) to stimulate breathing.

If excessive oxygen is administered:

• ✔ Ventilation may decrease in susceptible patients
• ✔ Carbon dioxide begins to accumulate
• ✔ PaCO₂ rises (hypercapnia)
• ✔ The patient may become drowsy, confused, or difficult to arouse (CO₂ narcosis)

👉 Therefore, the expected ABG finding is increased PaCO₂.

❌ Why Other Options Are Wrong?

(A) Decreased PaCO₂
❌ Incorrect. High-flow oxygen in susceptible COPD patients tends to increase, not decrease, PaCO₂.

(B) Increased PaO₂ Only
❌ Oxygen therapy raises PaO₂, but the key clinical concern in this scenario is the accompanying rise in PaCO₂.

(D) Increased pH
❌ Increased PaCO₂ causes respiratory acidosis, so the pH usually decreases, not increases.

📝 ABG Changes in Oxygen-Induced Hypercapnia

📌 Exam Tip: In COPD, oxygen should be administered carefully and titrated to a target oxygen saturation of about 88–92% in patients at risk of hypercapnic respiratory failure. Excessive oxygen may lead to oxygen-induced hypercapnia, characterized by increased PaCO₂ and drowsiness.