Longitudinal changes in muscle mass after ICU discharge: A prospective observational cohort study.

BACKGROUND

There is limited published data describing patterns of muscle wasting after critical illness. Muscle ultrasound is a practical method to monitor changes in muscle mass after Intensive Care Unit (ICU) discharge. The aim of this study was to investigate longitudinal changes in muscle mass after ICU discharge in a group of mixed medical-surgical ICU patients.

METHODS

Adult ICU patients (n = 42) with a minimum length of stay in ICU of 3 days were prospectively enrolled. Baseline measurements of quadriceps muscle layer thickness, Medical Research Council sum score, hand grip strength and indirect calorimetry were performed in conjunction with ICU discharge and repeated every 3-5 days until hospital discharge or up to 28 days. The primary outcome was change in muscle thickness over time. Secondary outcomes were changes in physical function. Outcomes were assessed using best-fit generalized linear mixed models according to the Akaike information criteria. Interactions between outcomes and relevant covariates were investigated for hypothesis-generating purposes.

RESULTS

In the best-fit crude analysis model, a small but statistically significant change in muscle thickness over time (p = 0.0475) was observed. In exploratory covariate analysis, there was a strong interaction between body weight, female sex, low nutritional intake and increased loss of muscle thickness. Assessments of physical function improved over time. Female sex and ICU length of stay were identified as potential predictors of impaired physical recovery.

CONCLUSIONS

In this cohort of adult ICU patients, we did not find a relevant group-level change in muscle mass after ICU discharge. However, patients with poor nutritional intake and female sex may be at greater risk of muscle wasting after intensive care. Further studies are warranted to investigate the relevance of post-ICU nutrition and gender on recovery of muscle mass after critical illness.

TRIAL REGISTRATION: This study was prospectively registered at ClinicalTrials.gov on 2022-09-02 (NCT05531305).