The resistance of collateral channels in excised human lungs

channels, Reol in incomplete interlobar fissures in eight normal and eight emphysematous excised human lungs. Similar measurements were also made from the basal segments to the superior segment of the lower lobe in three normal and five emphysematous lungs. The lobe or segments were inflated through a bronchial cannula; air leaked through collateral channels and out of the other lobe or segment through a pneumotachograph which measured flow. Catheters inserted directly into the lung through the pleural surface on either side of the collateral channels measured the alveolar pressure dif-ference producing collateral flow. Reo. is the ratio of this pressure difference to flow. By also measuring the in-flating pressure and the airway pressure at the pneumo-tachograph, we calculated the lobar or segmental air-way resistance, Raw,. In the normal lungs Rco. varied inversely with lung volume and was higher on inflation than on deflation. Raw was very small compared to R,0. which ranged from 260 to 3300 cm H20/liter per sec when the distending pressure was 20 cm H20. In the emphysematous lungs on the other hand, Rco. was markedly decreased and ranged from 5 to 20 cm H20/ liters per sec at the same distending pressure and was less than Raw. We conclude that collateral channels are important ventilatory pathways in emphysema. When many units within a lung are ventilated by these path-ways there may be disturbances of gas exchange and phase differences between normally and abnormally ventilated areas