title: The "baby lung" became an adult.
abstract: The baby lung was originally defined as the fraction of lung parenchyma that, in acute respiratory distress syndrome (ARDS), still maintains normal inflation. Its size obviously depends on ARDS severity and relates to the compliance of the respiratory system. CO2 clearance and blood oxygenation primarily occur within the baby lung. While the specific compliance suggests the intrinsic mechanical characteristics to be nearly normal, evidence from positron emission tomography suggests that at least a part of the well-aerated baby lung is inflamed. The baby lung is more a functional concept than an anatomical one; in fact, in the prone position, the baby lung "shifts" from the ventral lung regions toward the dorsal lung regions while usually increasing its size. This change is associated with better gas exchange, more homogeneously distributed trans-pulmonary forces, and a survival advantage. Positive end expiratory pressure also increases the baby lung size, both allowing better inflation of already open units and adding new pulmonary units. Viewed as surrogates of stress and strain, tidal volume and plateau pressures are better tailored to baby lung size than to ideal body weight. Although less information is available for the baby lung during spontaneous breathing efforts, the general principles regulating the safety of ventilation are also applicable under these conditions.
authors.affiliation: Dipartimento di Anestesia, Rianimazione ed Emergenza Urgenza, Fondazione IRCCS Cà Granda-Ospedale Maggiore Policlinico, Milan, Italy. gattinon@policlinico.mi.it.|Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Via Francesco Sforza 35, 20122, Milan, Italy. gattinon@policlinico.mi.it.
authors.forename: Luciano
authors.initials: L
authors.lastname: Gattinoni
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Saint Paul, MN, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Marini
authors.affiliation: Dipartimento di Anestesia, Rianimazione ed Emergenza Urgenza, Fondazione IRCCS Cà Granda-Ospedale Maggiore Policlinico, Milan, Italy.|Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Via Francesco Sforza 35, 20122, Milan, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pesenti
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Göttingen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Quintel
authors.affiliation: Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Mancebo
authors.affiliation: Keenan Research Centre, Li Ka Shing Knowledge Insitute, Critical Care Department, St. Michael's Hospital, Toronto, ON, Canada.|Interdepartmental Division of Critical Care Medicine, Toronto, ON, Canada.
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
mesh_terms: D001784:Blood Gas Analysis; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D011175:Positive-Pressure Respiration; D016684:Prone Position / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology; D012720:Severity of Illness Index; D013990:Tidal Volume / Q000502:physiology
keywords: ARDS; Baby lung; Prone position; Stress and strain; Transpulmonary pressure