Cardiopulmonary interaction during sleep

The Greek physician Miltus (570 BC) stated that pneuma, or breath, was the essence of all things (1). It took a millennium before we understood that its primary purpose is that of gas exchange. Assessments of lung function focus on defining the properties of the respiratory system. The respiratory muscles form part of the pump, together with the lungs and the chest wall (2). By contracting, they change the chest wall configuration, displacing its components, so that air can move in and out of the lungs (2). The respiratory muscles must overcome the mechanical properties of the pump for ventilation to be effective, at a bearable energy cost (2). In this chapter we will review lung function and respiratory mechanics that are relevant to pulmonary rehabilitation.