Marked losses of computed tomography-derived skeletal muscle area and density over the first month of a critical illness are not associated with energy and protein delivery

Objectives: Changes in muscularity during different phases of critical illness are not well described. This retrospective study aimed to describe changes in computed tomography (CT)-derived skeletal muscle area (SMA) and density (SMD) across different weeks of critical illness and investigate associations between changes in these parameters and energy and protein delivery. Methods: Thirty-two adults admitted to the intensive care unit (ICU) who had >= 2 CT scans at the third lumbar area performed >= 7 d apart were included in the study. CT-derived SMA (cm(2)) and SMD (Hounsfield units) were determined using specialized software. A range of clinical and nutrition variables were collected for each day between comparator scans. Associations were assessed by Pearson or Spearman correlations. Results: There was a significant decrease in SMA between the two comparator scans where the first CT scan was performed in ICU wk 1 (n = 20; P < .001), wk 2 (n = 11; P < .007), and wk 3 to 4 (n = 7; P = .012). There was no significant change in SMA beyond ICU wk 5 to 7 (P = .943). A significant decline in SMD was observed across the first 3 wk of ICU admission (P < .001). Overall, patients received a mean 24 +/- 6 kcal energy/kg and 1.1 +/- 0.4 g protein/kg per study day and 83% of energy and protein requirements according to dietitian estimates. No association between SMA or SMD changes and nutrition delivery were found. Conclusions: Critically ill patients experience marked losses of SMA over the first month of critical illness, attenuated after wk 5 to 7. Energy and protein delivery were not associated with degree of muscle loss. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

This retrospective study aimed to describe changes in computed tomography (CT)-derived skeletal muscle area (SMA) and density (SMD) across different weeks of critical illness. It found that critically ill patients experience marked losses of SMA over the first month of critical illness, with energy and protein delivery not associated with degree of muscle loss.