N. LeRoy Lapp

Physiological approaches to detection of small airway disease

Abstract Recent developments in the field of lung mechanics relating to the problem of obstructive airway disease and its detection are reviewed. The importance of studying the behavior of the intrapulmonary airways during the compressed as well as the noncompressed state is stressed. The role of premature “airway closure,” in contributing to the abnormalities of gas exchange associated with disease in the small peripheral airways is discussed. The possibility is explored that some alternative methods for detecting small airway disease other than frequency dependence of dynamic compliance may be developed. Some physiological approaches to studying the behavior of small peripheral airways in human subjects during life are presented.

ELECTRON MICROSCOPIC FINDINGS IN THE LUNGS OF MINERS

Tissue was obtained from the lungs of four subjects who had been exposed to bituminous coal dust in the course of their work. Three had been mainly underground coal miners; the fourth worked as a boiler repairman at a power plant that burned bituminous coal. Details regarding age, number of years’ exposure, and job classification, insofar as they could be determined, are presented in TABLE 1. In the case of each underground coal miner, the tissue was obtained at autopsy from an unfixed lung. Lung tissue from the boiler repairman was obtained by surgical biopsy at the time of an operation to replace a stenosed mitral valve, which had resulted from rheumatic fever at age 13. One portion of each tissue specimen was immediately placed in 7% collidine buffered glutaraldehyde solution for examination by the electron microscope. Another portion was placed in formalin solution and processed by routine methods for histologic examination by light microscopy in the Department of Pathology at West Virginia University Medical Center, Morgantown, West Virginia. The specimen in the glutaraldehyde solution to be examined by electron microscopy was air-mailed to California, where the tissue was post-fixed in 1 % osmium tetroxide for one hour, dehydrated in graded acetone, and embedded in Aralditea 502 resin. Sections were cut from the cured blocks with a diamond knife on a Porter-Blum I microtome, picked up on uncoated grids, and stained first with lead and then with uranyl acetate. These grids were then examined with a Philips 300 electron microscope. When possible, a chest x-ray taken prior to the time of obtaining lung tissue was selected; photographs of these x-rays are included in FIGURE la-d. Pulmonary function studies were performed on two of the subjects. For