The National Institutes of Health Intermittent Positive-Pressure Breathing Trial: pathology studies. IV. The Destructive index.

A Destructive Index (DI) was recently devised by Saetta and coworkers (7), and their data suggest that the DI may be a better assessment of emphysema than the traditional indexes. We have applied the DI as well as conventional assessments of emphysema-panel grading (emphysema score), mean linear intercept (Lm), and internal surface area at a volume of 5 L (ISA5) - to the lungs of patients in the National Institutes of Health Intermittent Positive Pressure Breathing Trial, which admitted patients with moderate to severe chronic airflow obstruction. In the 41 patients with satisfactory morphologic material who died and were autopsied, the DI was significantly correlated with emphysema score (p less than 0.001), Lm (p less than 0.001), and ISA5 (p less than 0.001). There was a rapid increase in the DI between emphysema scores of 30 and 60; when the DI reached a score of about 90, it did not increase much further. A wide spread of the DI from 23.7 to 86.5 was present in lungs with a Lm of less than 0.55 mm. The DI was well related to the diffusing capacity for carbon monoxide (DLCO) (p less than 0.001) and %TLC (p less than 0.01), but not to %FEV1, slope of phase III (phase III), nor recoil pressure at 90% of TLC (P90). The correlations between emphysema score and either DLCO or %TLC were about the same as for the DI. Also, correlations were significant for %FEV1, phase III, and P90. Lesions of bronchioles had no correlation with the DI. We therefore conclude that the DI is related to conventional assessments of emphysema, but beyond an emphysema score of 55 or a Lm of 0.55 mm, it does not discriminate emphysema severity.(ABSTRACT TRUNCATED AT 250 WORDS)