Harry M. Vars Award Candidate Abstracts

Background: Critical illness is associated with severe muscle wasting.A combination of protein supplementation and mobilization may attenuate muscle loss.We determined the effect of a combination of intravenous (IV) bolus amino acid (AA) supplementation and in-bed cycling, versus standard care only, on skeletal muscle mass during the first ICU week.Methods: This randomized controlled trial (ClinicalTrials.govNCT04099108) was undertaken in a predominantly trauma adult surgical ICU.Participants were randomly assigned into two groups, both of which received standard care nutrition (SCN) and mobilization.The intervention group received an additional IV AA bolus, starting on ICU day 3 on-average, along with a 45-minute in-bed cycling session for a mean of 6 days.Histological change in vastus lateralis (VL) myofiber cross-sectional area (CSA) and ultrasound rectus femoris (RF) muscle CSA was measured from pre-intervention (average ICU day 2) to post-intervention (average ICU day 8) and analyzed using mixed model ANOVA and post hoc least significant difference (LSD) testing.Secondarily, we assessed the change in the protein-to-DNA ratio over time.We further compared responses between participants with and without baseline organ dysfunction (defined as SOFA2, due to infection or trauma-related inflammation).Results: Fifty critically ill patients (90% male, mean age 3712 years, APACHE II score 13.56.6,SOFA score 4.53.2,BMI 24.84.0kg/m 2 , modified NUTRIC 2.21.8)were included.The control (n = 25) and intervention (n = 25) groups received, on average, 87.6232.18and 85.5329.29 grams of protein per day (1.260.41 and 1.290.40g/kg/day,respectively) from SCN, and the intervention group an additional 30.435.62 grams of AA (0.370.06g/kg protein equivalents) from the supplement.There was significant loss of muscle mass over time in all participants (VL myofiber CSA 11.76%, p = 0.011; RF muscle CSA 13.01%p < 0.001).No significant difference was found between groups, but a more compatible trend for greater muscle loss in the control group versus the intervention group (p = 0.051 vs p = 0.067) (Table 1).Protein-to-DNA ratio rose significantly over time (p = 0.007) but was significant only in the intervention group (control 11.33%, p = 0.177; intervention 20.96%, p = 0.007) (Table 1).A mixed model ANOVA adjusting for baseline organ dysfunction revealed a significant study group effect (p = 0.012).Post-hoc LSD comparisons showed that in participants without baseline organ dysfunction, the control group had significantly greater VL myofiber CSA loss (pre: 3803.19 vs. post: 2845.60,p = 0.034), while no significant loss was observed in the intervention group (pre: 4580.19 vs. post: 4393.86,p = 0.787). Conclusion:Significant muscle mass loss occurs during the first ICU week.While no significant difference was observed between the control and intervention groups, the latter showed a significant increase in the protein-to-DNA ratio, indicating potential benefit on muscle protein content.Additionally, our findings suggest that the intervention may be more effective in patients without baseline organ dysfunction.Future