Thoracic Skeletal Muscle Quantification Using Computed Tomography And Prognosis Of Elderly ICU Patients

Abstract Background: In elderly ICU patients, the prevalence of skeletal muscle loss is high. And the consequences of skeletal muscle loss can be severe in elderly. Correlations have been found between the muscle cross-sectional area (CSA) at a single thoracic level on chest computed tomography (CT). Correlation between thoracic muscle mass and mortality has been found in ICU patients. But longitudinal effect of thoracic muscles especially in elderly ICU patients are unclear although skeletal muscle loss is related with the short- and long-term outcomes. Objective: This study aimed to evaluate whether pectoralis muscle mass could be a predictor of prognosis in elderly ICU patients.Methods: We retrospectively evaluated 190 elderly patients admitted in the ICU between January 2010 and December 2015 in one tertiary care hospital in South Korea. We measured the CSA of the pectoralis muscle area (PMCSA) at the fourth vertebral region. CT scans within two days before ICU admission were used for analysis. Mortality, prolonged mechanical ventilation, and longitudinal change in Sequential Organ Failure Assessment (SOFA) scores were examined. Multivariate logistic regression, linear mixed, and multivariate Cox proportional hazards models were used.Results: PMCSA below median was significantly related with prolonged ventilation. (odds ratio 2.92, 95% CI: 1.02-1.42, P=0.06) and a higher SOFA score during the ICU stay (estimated mean = 0.94, P = 0.03). PMCSA below median was a significant risk for all-cause mortality (HR: 2.06, 95% CI: 1.23-3.47, P=0.01)Conclusions: In elderly ICU patients, low ICU admission PMCSA was associated with prolonged ventilation, a higher SOFA score during the ICU stay and higher mortality. Adding thoracic skeletal muscle CSA at the time of ICU admission into consideration in deciding therapeutic intensity in elderly ICU patients may help in making medical decisions.