Human alveolar fractal dimension in normal and chronic obstructive pulmonary disease subjects

We have determined that fractal analysis of the alveolar perimeter (D(f)) changes with aging in human lung tissue in twenty-nine patients, age range of 25 hours to 76 years, who died of non-respiratory related causes. There was a very significant difference (p = 0.0004) in D(f) between the young (less than 16 years old, N=9, mean D(f) of 1.047 [0.01]) and adult (greater than 16 years old, N=20, mean D(f) of 1.093 [0.013]) groups. Furthermore, there was a significant difference in D(f) between the Adult group and the group of patients who died of chronic obstructive pulmonary disease (COPD, N=10) (p = 0.012). Additionally, the D(f) values for the COPD and cystic fibrosis (CF, N = 5) groups were virtually identical; 1.061 and 1.070, respectively. Regression analysis showed a significant (p = 0.0041) exponential relationship with a correlation coefficient of 0.59 between aging and D(f). We have demonstrated that the correlation between D(f) and aging in humans is an exponential function and that the end-stage pulmonary diseases of COPD and CF decrease D(f).