Skeletal Muscle Index at Intensive Care Unit Admission Is a Predictor of Intensive Care Unit-Acquired Weakness in Patients With Sepsis

BACKGROUND: Intensive care unit-acquired weakness (ICU-AW) can be diagnosed using the Medical Research Council (MRC) score. However, such scoring may not be possible in ICU patients who may be sedated or delirious or have encephalopathy. Currently, a quantitative assessment of the cross-sectional area of the muscle is available to assess changes in skeletal muscle mass using computed tomography (CT) images. This assessment calculates the skeletal muscle index (SMI) (cm(2)/m(2)) by dividing the cross-sectional area (cm(2)) of the skeletal muscle at the level of the third lumbar vertebra by the square of the patient’s height (m(2)) on CT. This study assessed the effectiveness of SMI, as measured by abdominal CT scans, in predicting the onset of ICU-AW in patients with sepsis admitted to the ICU. METHODS: We examined septic ICU patients admitted to the Niigata University Hospital ICU during 2012 - 2017 under mechanical ventilation. Patients were retrospectively divided into two groups by MRC score at ICU discharge: group AW comprised patients with an MRC score < 48, and group non-AW (NAW) comprised the remaining patients. Clinicopathological factors at ICU admission such as age, gender, underlying disease, body mass index, and SMI were compared between the two groups. Statistical analyses were performed using the Mann-Whitney U test, Fisher’s exact test, receiver operator characteristic (ROC) analysis and multivariate analysis. RESULTS: A total of 31 septic patients were examined, and 23 patients met the criteria for ICU-AW. The prevalence of women was significantly higher in group AW (P < 0.05). All clinical factors, except for gender, were not significantly different between the two groups. SMI was significantly lower in group AW than in group NAW (P < 0.05). ROC analysis revealed that the cut-off value of SMI for predicting ICU-AW was 44.1, and the multivariate analysis revealed that only low SMI was a significant factor in predicting ICU-AW (P < 0.05). CONCLUSIONS: Our results show that SMI measurement at ICU admission is a valid predictive factor for ICU-AW progression in septic patients.