Prone positioning is a life-saving treatment used in ARDS patients in order to improve oxygenation and reduce lung injury due to mechanical ventilation. The beneficial effects of this procedure are the result of complex mechanisms that cooperate in improving gas exchange and in reducing global \u201cstress\u201d and \u201cstrain\u201d of the lung. Prone positioning seems to be more effective in extrapulmonary form of ARDS, where the main feature of the disease is represented by compression atelectasis in dependent lung regions caused by the gain in lung weight due to pulmonary edema. To date, it is recommended in ARDS patients that maintain a PaO2/FiO2ratio lower than 150 mmHg even after optimization of mechanical ventilation. However, only...