Lobar pressure-volume characteristics of excised human lungs.

The pressure-volume (P-V) characteristics were investigated in 14 excised left human lungs and their individual lobes. Comparison of the upper and lower lobar P-V curves of the emphysema-free and emphysematous lungs showed no significant difference when plotted as per cent lobar volume at a transpulmonary pressure (PL) of 30 cm H2O (V30). However, when in the emphysematous lungs the more severely involved lobes were compared with the less severely involved lobes, significant differences in the PL 60-90% V30 were found, the more severely involved lungs exhibited a higher PL. The mean linear intercepts were identical in the upper and lower lobes of the emphysema-free lungs indicating equal distension and validating expression of the P-V data as per cent V30. However, in he emphysematous lungs, in which the upper lobes were more severely involved, the linear intercepts tended to be larger in the upper lobes and the ratio of upper to lower lobe V30 tended to be larger than in the emphysema-free lungs. Thus, in the emphysematous lungs, comparison of the lobar P-V curves expressed as per cent V30 may not be valid.