What can contribute to hypoventilation in postoperative patients?

Hypoventilation in postoperative patients can be significantly influenced by factors that increase airway resistance. Increased airway resistance can stem from various issues, such as excessive secretions, bronchospasm, or obstruction caused by mucus. These conditions make it more difficult for patients to breathe effectively, leading to reduced tidal volume and inadequate ventilation, which can result in hypoventilation.

In contrast, deep breathing exercises and the use of incentive spirometry are both therapeutic measures designed to facilitate better lung expansion and improve ventilation. They help in clearing secretions and promoting deep, effective breathing, thereby reducing the risk of hypoventilation. Early ambulation also contributes positively by promoting lung function and preventing complications associated with immobility, such as atelectasis. Thus, the factor that leads to hypoventilation in this context is the increased airway resistance, making it the correct answer.