ARDS: Who Needs to be Pronated?

Abstract

Acute Distress Respiratory Syndrome (ARDS) is defined as a severe respiratory failure characterized by marked hypoxemia, bilateral infiltrates on the chest X-ray and the absence of signs of cardiogenic pulmonary edema. ARDS treatment remains primarily supportive and the use of mechanical ventilation with positive and expiratory pressure is required to maintain adequate gas exchange. Lung-protective mechanical ventilation strategy decreases mortality and increases ventilator free days. Prone positioning is considered a rescue therapy despite it improves gas exchange through resolution of dorsal atelectases with lung recruitment, better distribution of pulmonary perfusion and reduction of lung stress and strain. Nevertheless, several randomized controlled trials failed to demonstrate a reduction in mortality in pronated ARDS patients. Recent meta-analysis instead demonstrated a significant reduction of mortality in patients with most severe ARDS (PaO2/FiO2 ratio < 200) ventilated in prone position. These data were confirmed by the results of the PROSEVA study, published in June 2013 that reports a 16% reduction of mortality rate. The results of several meta-analysis and this large clinical trial suggest that prone positioning is a useful strategy that saves lives in more severely ill ARDS patients, when applied earlier and for at least 16 hours/day.