ABSTRACT
In acute respiratory distress syndrome, the role of positive end-expiratory pressure (PEEP) to prevent ventilator-induced lung injury is controversial. Randomized trials comparing higher versus lower PEEP strategies failed to demonstrate a clinical benefit. This may depend on the inter-individually variable potential for lung recruitment (i.e. recruitability), which would warrant PEEP individualization to balance alveolar recruitment and the unavoidable baby lung overinflation produced by high pressure. Many techniques have been used to assess recruitability, including lung imaging, multiple pressure-volume curves and lung volume measurement. The Recruitment-to-Inflation ratio (R/I) has been recently proposed to bedside assess recruitability without additional equipment. R/I assessment is a simplified technique based on the multiple pressure-volume curve concept: it is measured by monitoring respiratory mechanics and exhaled tidal volume during a 10-cmH