Now that Dr Gattinoni and I have had a chance to examine our respective arguments, it is obvious that the terms “low” and “all” were not specific enough attributes of tidal volume (Vt) and patients, respectively, on which to base our debate. Whereas I1 have focused on the merits of lowering Vt relative to historic norms for all patients, meaning even those without lung injury, Dr Gattinoni2 has emphasized that not all patients with injured lungs should get the same low Vt (ie, 6 mL/kg predicted body weight (PBW) as recommended by the ARDS Network).3 I could not agree more! Indeed, our group has recently put forth the very same argument.4 The only nuance on which Dr Gattinoni and I may differ relates to the “fuzziness” in the cause and effect relationship between strain, as defined by him, and lung injury.5 Whereas I favor the use of the Vt to total lung capacity (TLC) ratio (Vt/TLC) to quantify lung deformation, Dr Gattinoni favors strain, defined as the difference between the volume at end inspiration and that at zero end-expiratory pressure (VZEEP), normalized by VZEEP. Before I explain why I believe that my way of approaching the issue is more intuitive and useful, I want to underscore the shared premise, namely, that scaling Vt to the size of the injured lung is important. Predicted body weight scales with the size of the healthy lung (ie, the number of recruitable alveoli), but not with the capacity of a diseased lung. Given the large variability in disease-related unit drop-out, a “one size fits all” approach would expose the sickest patients, those with the “smallest lungs,” to the largest deforming stresses. Therefore, the size of the injured, as opposed to that of the healthy, lung needs to be considered when arriving at patient-protective ventilator settings. One way of doing so is to measure VZEEP using a gas dilution method, as proposed by Chiumello et al.6 How this information is used is where Dr Gattinoni and I differ.