Computed tomography reveals hypertrophic remodelling of the diaphragm in cystic fibrosis but not in COPD

Fatemeh Ostadan; Adamo A Donovan; Elias Matouk; Francois Gabriel David; Dylan Marchand; Caroline Reinhold; Dao Nguyen; Peter Goldberg; Andrea Benedetti; Benjamin M Smith; Basil J Petrof

doi:10.1183/23120541.00282-2023

Computed tomography reveals hypertrophic remodelling of the diaphragm in cystic fibrosis but not in COPD

ERJ Open Res. 2023 Sep 25;9(5):00282-2023. doi: 10.1183/23120541.00282-2023. eCollection 2023 Sep.

Authors

Fatemeh Ostadan¹, Adamo A Donovan², Elias Matouk³, Francois Gabriel David^{1

4}, Dylan Marchand¹, Caroline Reinhold⁵, Dao Nguyen^{1

3}, Peter Goldberg^{1

3

4}, Andrea Benedetti^{2

6}, Benjamin M Smith^{1

2

3}, Basil J Petrof^{1

3}

Affiliations

¹ Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
² Respiratory Epidemiology and Clinical Research Unit, Centre for Outcomes Research and Evaluation, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
³ Respiratory Division, Department of Medicine, McGill University, Montreal, QC, Canada.
⁴ Department of Critical Care, McGill University, Montreal, QC, Canada.
⁵ Department of Radiology, McGill University, Montreal, QC, Canada.
⁶ Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC, Canada.

Abstract

Background: Computed tomography (CT) is increasingly used for assessing skeletal muscle characteristics. In cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD), reduced limb muscle mass predicts poor clinical outcomes. However, the degree to which quantity or quality of respiratory and nonrespiratory muscles is affected by these diseases remains controversial.

Methods: Thoracic CT images of 29 CF, 21 COPD and 20 normal spirometry control subjects were analysed to measure indices of muscle quantity (volume or cross-sectional area) and quality (radiodensity) in respiratory (diaphragm, abdominal) and nonrespiratory (pectoralis, lumbar paraspinal) muscles. Multivariable linear regression assessed relationships of CT measurements with body mass index (BMI), forced expiratory volume in 1 s (FEV₁) % pred, inflammation and infection biomarkers, nutritional status and CF genotype.

Results: Diaphragm volume in CF was significantly higher than in COPD (by 154%) or controls (by 140%). Abdominal muscle area in CF was also greater than in COPD (by 130%). Nonrespiratory muscles in COPD had more low radiodensity muscle (marker of lipid content) compared to CF and controls. In CF but not COPD, higher BMI and FEV₁ % pred were independently associated with higher diaphragm and/or abdominal muscle quantity indices. Serum creatinine also predicted respiratory and nonrespiratory muscle quantity in CF, whereas other biomarkers including genotype correlated poorly with muscle CT parameters.

Conclusions: Our data suggest that the CF diaphragm undergoes hypertrophic remodelling, whereas in COPD the nonrespiratory muscles show altered muscle quality consistent with greater lipid content. Thoracic CT can thus identify distinctive respiratory and nonrespiratory muscle remodelling signatures associated with different chronic lung diseases.