Resistance measurements. Forced oscillations and plethysmography

Whether a subject breathes spontaneously or is artificially ventilated, the pressure which must be applied to the respiratory system to ventilate (Prs) includes two basic components: 1) a static or elastic component (Pel) to sustain the elastic recoil of the lung and chest wall, as described elsewhere in this book; 2) a dynamic or resistive component (Pres) to provide for energy losses by friction occurring in the airways and in the tissues.