With this background, what can we say about the article by Carteaux et al12 in this issue of CHEST (see page 367)? First, confirmation of the laboratory findings in a clinical study is unique and gives the results clinical meaning. The laboratory study uses a clinically relevant simulation of breathing patterns and leaks but is limited by using only a single set of lung mechanics, only one breathing pattern, and only one inspiratory and expiratory leak. Even here, the authors should be congratulated for modeling a system in which the inspiratory leak is greater than the expiratory leak, which is more indicative of the clinical situation than the fixed leak used in other studies. Moreover, any limits of the bench trial can be overlooked because of the clinical study, which enrolled subjects with a variety of respiratory mechanics, breathing patterns, and leaks. A criticism of the clinical study is the use of the BiPAP Vision ventilator (Philips Respironics), which is no longer commercially available and has been replaced with the V60 ventilator. However, evidence from the bench study suggests that the performance of the V60 is at least as good, if not better, than the Vision. In the clinical study, Carteaux et al12 used an oronasal mask, so the results may not be transferrable to other interfaces where mouth leak is likely to occur.