Incidence of emphysema at necropsy as assessed by point-counting

The lungs from an unselected group of necropsies were fixed in inflation by boiling formaldehyde vapour, and the percentage of emphysema was determined by macroscopic point-counting. The emphysema was categorized into alveolar, centrilobular, bullous, and `mixed'. The term `mixed' emphysema was applied to cases which had a combination of two or all of the three forms.