CO 2 is produced by cell metabolism in large daily quantities.

Expired CO 2 kinetics integrates relevant pathophysiological information of high interest for monitoring. Clinicians have difficulties in detecting VILI, particularly cyclic overdistension at the bedside, since routine monitoring of gas exchange and lung mechanics are relatively insensitive to this mechanism of VILI. Theoretically, healthier lung regions are submitted to a larger stress and cyclic deformation and thus at high risk for developing VILI. Of major concern is cyclic overdistension, affecting those lung segments receiving a proportionally higher tidal volume in an overall reduced lung volume. The ARDS lung is characterized by diffuse and heterogeneous lung damage and is particularly prone to suffer the consequences of an excessive mechanical stress imposed by higher airway pressures and volumes during MV. However, MV can contribute to a worsening of the primary lung injury, known as ventilation-induced lung injury (VILI), which could have an important impact on outcome. Mechanical ventilation (MV) is a lifesaving supportive intervention in the management of acute respiratory distress syndrome (ARDS), buying time while the primary precipitating cause is being corrected. 8Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina.7Hospital Clinic, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.6Department of Anesthesiology and Critical Care, Hospital Clinic, Barcelona, Spain.5Keenan Research Center at the Li Ka Shing Knowledge Institute, St.Negrín, Las Palmas de Gran Canaria, Spain 4Multidisciplinary Organ Dysfunction Evaluation Research Network (MODERN), Research Unit, Hospital Universitario Dr.3Department of Surgical Sciences, Anesthesiology & Critical Care, Hedenstierna Laboratory, Uppsala University Hospital, Uppsala, Sweden.2Intensive Care Unit, Hospital Universitario La Princesa, Madrid, Spain.1CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.Fernando Suárez-Sipmann 1,2,3*† Jesús Villar 1,4,5† Carlos Ferrando 1,6,7† Juan A.

Volume of dead space in lungs