Management of the intensive care patient afflicted by respiratory insufficiency requires knowledge of the pathophysiological basis for altered functions. The etiology and therapy of pulmonary diseases, such as acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD) are highly complex. While physiologists and pathophysiologists work prevalently with theoretical modes, clinicians employ sophisticated ventilation support technologies in the attempt to understand the pathophysiological mechanisms of the pulmonary diseases which can present with varying grades of severity. Despite the availability of advanced technologies it is common to personalize the treatment protocol according to the patient''s physiologic structure.Given the complexity and difficulties of treating respiratory disease, a strong collaboration between clinicians and physiologists is of fundamtental importance.