Recent studies have shown that application of the ARDSNet low tidal volume strategy (i.e. allowing an increase in respiratory rate in order to minimize hypercapnia in those with low tidal volume) may generate consistent auto-PEEP (positive end-expiratory pressure), and this is not efficient in improving clearance of carbon dioxide. The present commentary deals with some of the recent controversies related to use of a low tidal volume strategy, as implemented in the ARDSNet trial, which has proved successful in reducing mortality rates in patients with acute respiratory distress syndrome. We emphasize the importance of basic physiological knowledge and sound respiratory monitoring.