What is a major factor predisposing to pulmonary infection in immobilized patients?

A major factor predisposing immobilized patients to pulmonary infection is the decreased ability to clear secretions from the airways. Immobility can lead to impaired cough reflex and reduced chest wall movement, resulting in stasis of secretions and increased risk of bacterial colonization and pneumonia. Additionally, prolonged bed rest can contribute to alterations in lung function and ventilation-perfusion mismatch, further exacerbating the risk of infection.