People who are admitted to the Intensive Care Unit (ICU) and receive mechanical ventilation are at risk of developing pneumonia. Many factors have been associated with an increased likelihood of developing this "ventilator-associated pneumonia" (VAP), including pre-existing respiratory disease, supine body positioning, and reduced consciousness level.

Clinicians in the ICU would like to prevent their patients from developing VAP, because it increases mortality, length of stay, and healthcare costs. Retention of airway secretions is thought to contribute to the development of the problem.

To combat this, physiotherapists use various respiratory techniques intended to promote the clearance of airway secretion and improve lung expansion. These techniques can include manual techniques applied to the chest wall, delivering larger volume breaths to the patient, and suction of the tube in the patient's airway that connects them to the ventilator.