Grant: Travel Awards - Institute Community Support

Rationale: Chronic obstructive pulmonary disease (COPD) is associated with limb muscle atrophy and dysfunction, but studies of diaphragm morphology and function have yielded conflicting results. We assessed diaphragm morphology in living human subjects using computed tomography (CT scan), and hypothesized that diaphragm volume would be associated with COPD severity, inspiratory capacity, respiratory health status, and exercise capacity. Methods: CanCOLD is an on-going, population-based, longitudinal study of over 1,400 participants. Left hemi-diaphragm morphology was assessed in this population by reproducibly mapping the diaphragm area on contiguous axial CT images. Three-dimensional reconstruction of mapped areas yielded measures of hemi-diaphragm volume in the range of -150 to 150 Hounsfield units. Associations between diaphragm volume, expiratory flows, inspiratory capacity, respiratory health status, peak oxygen uptake per kg body weight (peak VO2), and peak work rate were assessed while adjusting for age, gender, height, body mass index, smoking status, and pack-years of the participants. Results: Left hemi-diaphragm morphology was assessed in 238 CanCOLD participants to date. A decrease in left hemi-diaphragm volume was associated with lower expiratory flows, inspiratory capacity, respiratory health status, peak VO2, and peak work rate. Conclusion: Diaphragm volume assessed by CT is associated with airflow obstruction, and lower inspiratory capacity, respiratory health status, and exercise capacity