Grieco DL, et al. - Researchers report the existence of airway closure among obese patients undergoing general anesthesia. Within the procedures of a clinical trial during gynecological surgery, respiratory/lung mechanics and lung volume were assessed in obese patients both before and after pneumoperitoneum, in the supine and Trendelenburg positions, respectively. Comparisons were performed between patients showing airway closure vs controls enrolled in the same trial and matched in 1:1 ratio by body mass index. They found obese patients frequently developed complete airway closure during anesthesia, which was worsened by Trendelenburg pneumoperitoneum, which raises airway opening pressure and alveolar pressure: besides preventing alveolar derecruitment, this causes respiratory mechanics to be misinterpreted and generates a pressure threshold to inflate the lung that can reach high values, widening concerns regarding the safety of pressure-controlled modes in this setting.