title: Dynamic respiratory mechanics in acute lung injury/acute respiratory distress syndrome: research or clinical tool?
abstract: OBJECTIVE
  Classic static measurements of lung mechanics have been used mainly for research purposes, but have not gained widespread clinical acceptance. Instead, dynamic measurements have been used, but interpretation of results has been hampered by lack of clear definitions. The review provides an overview of possible definitions and a description of methods for evaluating lung mechanics in acute lung injury/acute respiratory distress syndrome patients.
  
  
  RESULTS
  Compliance measured using static techniques is significantly higher compared to measurements during ongoing ventilation. This indicates that lung mechanic properties depend on flow velocity during inflation and the time allowed for equilibration of viscoelastic forces. Thus, methods for evaluating lung mechanics should be clearly defined in terms of whether they are classically static, i.e. excluding resistance to flow and equilibration of viscoelastic forces, or truly dynamic, i.e. including flow resistance and unequilibrated viscoelastic forces. New techniques have emerged which make it possible to monitor lung mechanics during ongoing, therapeutic ventilation, 'functional lung mechanics', where the impact of flow resistance on tube and airway resistance has been eliminated, providing alveolar pressure/volume curves.
  
  
  CONCLUSIONS
  Functional lung mechanics obtained during ongoing ventilator treatment have the potential to provide information for optimizing ventilator management in critically ill patients.
authors.affiliation: Department of Anesthesia and Intensive Care, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Ola
authors.initials: O
authors.lastname: Stenqvist
authors.forename: Helena
authors.initials: H
authors.lastname: Odenstedt
authors.forename: Stefan
authors.initials: S
authors.lastname: Lundin
mesh_terms: D006801:Humans; D008168:Lung / Q000503:physiopathology*; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial / Q000009:adverse effects / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology*; D015656:Respiratory Mechanics; D013990:Tidal Volume