Muscle loss is prevalent and severe in the ICU: A Canadian multi-centre study analyzing clinically acquired CT images

Abstract

Purpose Muscle weakness is a common and debilitating complication of critical illness. Understanding the prevalence, severity, and risk factors associated with intensive care unit (ICU) acquired weakness is challenging, as critically ill patients are often unable to participate in muscle strength assessments. Muscle cross-sectional area obtained from computed tomography (CT) scans can be used as a surrogate measure for muscle strength. The objective of this study was to investigate changes in muscle in the ICU using clinically acquired CT imaging. Methods For this multi-centre cohort study, we acquired baseline and follow-up CT abdominal scans for 171 ICU trauma and sepsis patients from four hospitals in Calgary, Canada. We measured mean psoas muscle cross-sectional area at the level of the third lumbar vertebra. Patient demographic and illness-related information were acquired using electronic medical records. Linear mixed models and regressions were used to assess risk factors. Results Patients experienced an 8% reduction in psoas muscle CSA (1.2 cm², IQR = 0.1, 2.3) over a median 9 days in the ICU. This represents a median muscle loss rate of 1% per day. The prevalence of substantial muscle loss (> 10%) was 43%. Patients with greater muscle at baseline or greater time in the ICU experienced more profound muscle loss. For sepsis patients, greater rate of muscle loss was associated with increased ICU mortality (p < 0.05). Conclusion Muscle loss in the ICU is common, especially among patients with longer ICU stays or greater baseline muscle. Greater rate of muscle loss is associated with mortality.