Fig. 1

Print-screen, originally depicted from the Jaeger infant whole-body plethysmograph showing breath-by-breath tracings from which effective specific resistance (sR_eff), and its reciprocal value, the effective, specific airway conductance (sG_eff) are computed using the integral of the tidal flow-volume area (upper tracing) and the integral of the plethysmographic shift-volume versus tidal volume area, the latter representing the specific resistive work of breathing (middle tracing). The crossbar clearly demonstrates that the zero-flow points are perfectly in phase