Which factor most contributes to postoperative atelectasis?

• A. Early ambulation after surgery
• B. Incentive spirometry
• C. Adequate pain control allowing full inspiration
• D. Sedation with opioids causing shallow breathing

Answer: (D)

Postoperative atelectasis happens when ventilation is too shallow to keep all alveoli open, so some areas collapse and gas exchange decreases. When opioids are given after surgery, they can suppress the respiratory drive and lead to shallower breaths with smaller tidal volumes. This reduces diaphragmatic movement and overall lung expansion, making it easier for alveoli to collapse, especially in the dependent parts of the lungs where ventilation is naturally lower. The result is increased risk of atelectasis.

In contrast, strategies that promote deep breathing and alveolar reopening help prevent this complication. Early ambulation encourages full chest expansion and movement of secretions; incentive spirometry physically prompts deep breaths to re-expand collapsed areas; and adequately managing pain so that the patient can take long, full inspirations supports lung inflation rather than suppressing it. However, when pain control relies on opioids, the sedation effect can override those benefits by causing shallow breathing, which is why opioid-induced shallow respiration is the factor most associated with postoperative atelectasis.