Prone ventilation refers to mechanical ventilation with the patient lying face-down (prone). It improves oxygenation in most patients with acute respiratory distress syndrome (ARDS) and improves mortality. The mechanism behind this effect is uncertain. Prone ventilation refers to mechanical ventilation with the patient lying face-down (prone). It improves oxygenation in most patients with acute respiratory distress syndrome (ARDS) and improves mortality. The mechanism behind this effect is uncertain. Prone ventilation may improve oxygenation by redistributing pulmonary blood flow, but some research has shown that this improved oxygenation is not accompanied by a change in survival.