Quantitative peripheral muscle ultrasound in sepsis: Muscle area superior to thickness

Abstract Purpose The objective of this study is to describe the relationship between two quantitative muscle ultrasound measures, the rectus femoris cross-sectional area (RF-CSA) and quadriceps muscle thickness, with volitional measures of strength and function in critically ill patients with sepsis. Materials and methods We performed a prospective study of patients admitted to a medical ICU with sepsis and shock or respiratory failure. We examined the association of two ultrasound measurements – the RF-CSA and quadriceps muscle thickness – with strength and function at day 7. Strength was determined using the Medical Research Council Score and function using Physical Function in the ICU Test, scored. Results Twenty-nine patients were enrolled; 19 patients had outcome testing performed. Over 7 days, RF-CSA and thickness decreased by an average of 23.2% and 17.9%, respectively. The rate of change per day of RF-CSA displayed a moderate correlation with strength (ρ 0.51, p -value 0.03) on day 7. Baseline and day 7 RF-CSA did not show a significant correlation with either outcome. Quadriceps muscle thickness did not significantly correlate with either outcome. Conclusions Muscle atrophy as detected by the rate of change in RF-CSA moderately correlated with strength one week after sepsis admission.