What effect does proning have on patients with severe ARDS?

Proning, or placing a patient in a face-down position, has been shown to have significant benefits for patients with severe Acute Respiratory Distress Syndrome (ARDS). One of the primary effects is the reduction of shunting and improvement of the ventilation-perfusion ratio. In ARDS, consolidated lung regions may not participate effectively in gas exchange, leading to areas of shunting where blood flows through poorly ventilated regions. By changing a patient’s position to prone, gravity assists in recruiting collapsed or fluid-filled alveoli in the posterior regions of the lungs, facilitating better ventilation and improving overall gas exchange. This positioning optimally distributes blood flow and ventilation, which enhances the ventilation-perfusion ratio, making it more efficient for oxygenation.

Proning can lead to improved oxygenation indices and reduce the need for higher levels of supplemental oxygen or mechanical ventilation, thereby addressing some of the underlying pathophysiological features of ARDS. While other concerns regarding the risks, such as pressure ulcers or the potential impacts on oxygen demand, may arise with this intervention, the primary and documented physiological benefit is the improvement in lung mechanics and gas exchange.