Collateral ventilation in excised human lungs

Abstract

Pressure-volume (PV) curves and single-breath nitrogen (SBN) washout traces were obtained in 32 excised human lungs. Comparison of the volumes at the onset of phage IV of the SBN traces (V phase IV) and the volumes at the inflection points (VIP) of the PV curves revealed V phase IV to be significantly larger than VIP. We postulated that V phase IV was caused by bulk airway closure and that the difference between V phase IV and VIP was due to collateral ventilation. To test this we correlated V phas IV -- VIP with age and emphysema grades of the lungs. Significant correlations were obtained, demonstrating that with increasing age and emphysema grade V phase IV -- VIP also increased. This is consistent with the documented evidence for decreased resistance to collateral ventilation with increasing age and emphysema. In addition, in a total of 86 lungs we demonstrated that with increasing age and emphysema there is an increasing incidence of total lack of sigmoid deviation in the PV curve.