The purpose of this study was to quantify diaphragm muscle cell morphology, fiber size, and inflammatory cells in people with acute (ARD), acute and chronic (ARD/CRD), or no respiratory disease (NRD) post-mortem. Methods: Diaphragm biopsies and medical charts were examined from 28 subjects post-mortem: 10 people had ARD, 10 had ARD/CRD, and 8 had NRD. Diaphragm cross-sections, stained with hemotoxylin and eosin, were examined using computerized point counting to determine the area fractions (AA) of connective tissue, abnormal muscle tissue, and normal muscle tissue. White cells were counted from diaphragm cross-sections processed using immunohistochemical technique against the antigens, CD68, NP57, CD20 and CD8, to illustrate macrophages, neutrophils, B-lymphocytes, and T-lymphocytes, respectively.
Abnormal cytoplasm, and internalized nuclei were the most common morphologic abnormalities observed in the muscle fibers of the diaphragm. Patients with ARD only, and ARD/CRD had a greater AA of abnormal muscle tissue and a smaller AA of normal muscle tissue in the diaphragm than those with NRD (p<0.01). Macrophages were the most commonly observed leukocytes whereas neutrophils, B-lymphocytes, and T-lymphocytes were rare. White cell counts, including macrophages were not different between groups.
Acute respiratory disease with or without chronic respiratory disease is associated with morphologic changes which have possible links to diaphragm injury. The susceptibility of the diaphragm to injury should be considered while prescribing interventions that load this muscle such as weaning and inspiratory muscle training.
1Division of Physical Therapy
2The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, and the
3Respiratory Division of the University of British Columbia
4Pathology Departments at Vancouver Coastal and St. Paul's Hospital, Vancouver, British Columbia, Canada
Address correspondence to: Dr. W. Darlene Reid, Muscle Biophysics Laboratory, Vancouver Coastal Health Research Institute, Room 500 - 828 W. 10th Avenue, Vancouver, B.C. Canada V5Z 1L8, Ph: 604-875-4111 ext 66056, Fax: 604-875-4851 (email@example.com).