Work of breathing in a nonlinear human lung model

Work of breathing (WOB) functions associated with the mechanics of breathing are identified, based on a nonlinear model of the human lung and using a Lagrangian approach. Total and dissipative WOB values are computed numerically for three spontaneous breathing maneuvers (tidal, panting and forced vital capacity) of the same subject. An additional simulation reveals the effect of changing lung tissue compliance on WOB. The energy analysis provides valuable insight into the mechanics of respiration, and, in particular, the significance of individual model components. It provides the basis for sensitivity and optimization studies of the respiratory function, especially in the context of evaluating ventilator-dependent patients.