The quest for optimal positive end-expiratory pressure continues

With interest we have read the paper by Carvalho and colleagues, in which the authors report the results of their elegant study on the role of positive end-expiratory pressure (PEEP) in acute lung injury [1]. Carvalho and colleagues demonstrated in an acute respiratory distress syndrome (ARDS) model that alveolar hyperinflation and nonaerated areas may coincide during a stepwise reduction of PEEP. Their finding is in line with our findings in a mathematical ARDS model and with other studies [2,3], and emphasises that the PEEP at which the respiratory system compliance is maximal coincides with a compromise between hyperinflation and poor aeration [3].