Manske, Sarah LynnSmith, Ainsley Catherine Joan2024-05-282024-05-282024-05-23Smith, A. C. J. (2024). Investigating musculoskeletal changes in critically ill patients with computed tomography (CT) imaging (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118844https://doi.org/10.11575/PRISM/46441Critical care patients are susceptible to musculoskeletal changes during their stay in the intensive care unit (ICU). Intensive care unit acquired weakness (ICU-AW) is a common complication of critical illness that is characterized by a significant loss of muscle strength. ICU-AW can lead to long-term weakness, fractures, physical impairment, and reduced quality of life. Evaluating musculoskeletal health in the ICU can be challenging as patients are often non-responsive and unstable. However, critical care patients typically undergo computed tomography (CT) imaging for their clinical care, which can be repurposed for musculoskeletal assessment. The purpose of this thesis was to use clinically acquired CT images and electronic medical record data to investigate the effects of critical illness on the musculoskeletal system. CT imaging provides measures of muscle cross-sectional area, indicating muscle atrophy; muscle density, indicating muscle quality; and bone mineral density (BMD), indicating fracture risk. First, I adapted and validated a CT internal calibration method for reliable muscle density analysis. I then applied this internal calibration method to clinically acquired CT images of critical care patients, and I found that critical care patients undergo a significant reduction in psoas and thigh muscle density over the course of critical illness. Further, I applied CT internal calibration to evaluate BMD changes in critical care patients, and no changes were observed. In a larger cohort, I used clinically acquired CT images to determine that critical care patients experience significant psoas muscle atrophy during their ICU stay. Using electronic medical record data, I found that this muscle atrophy was associated with length of time in the ICU and quantity of muscle at ICU admission. Further, rate of muscle atrophy was associated with ICU mortality. The findings from this thesis provide insight into the effects of critical illness on the musculoskeletal system, the risk factors and mechanisms associated with muscle loss in the ICU, and the utility of clinically acquired CT imaging for retrospective musculoskeletal assessment.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Computed tomographyInternal calibrationMusculoskeletalCritical illnessIntensive care unit acquired weaknessBone mineral densityMuscle cross-sectional areaMuscle densityMedicine and SurgeryRadiologydoctoral thesis