Fig. 3.

Cumulative pressure drop from generation 7 (corresponding to a bronchus serving the apneic unit 1% volume) to generation 23, as a function of the degree of diameter narrowing α (expressed in percent), given by ΔP(7)/(1−α/100)⁴.ΔP(z) is defined in the legend to Fig. 2. Pressure required for collapse (dashed line) is estimated in the text (Pressure drops associated with collapse) to be around 4 cmH₂O.