Ultrasound Assessment of Quadriceps Muscle Layer Thickness as a Predictor of Outcome in Critically ill Patients

Aim: Muscle weakness in critically ill patients is associated with complications, but its accurate quantification at the bedside remains challenging.Our aim was to assess whether loss of quadriceps muscle layer thickness (QMLT) predicts mortality, and to examine its correlation with duration of mechanical ventilation and other severity indices. Materials and Methods:A total of 100 intensive care unit (ICU) patients were prospectively assessed with QMLT measurements on the dominant side on days 1, 3, and 7 of the ICU stay, or on the day of discharge, whichever occurred earlier.Results: Percentage decline in QMLT on days 3 and 7 (or discharge) was a significant predictor of mortality [for day 3: hazard ratio (HR): 1.06, 95% confidence interval (CI): 1.03-1.1,p=0.001; for day 7 or discharge: HR: 1.05, 95% CI: 1.02-1.07,p=0.0002].The decline in QMLT correlated well with mortality (p=0.50, p<0.001 at day 3, and p=0.77, p<0.001 at day 7 or on the day of discharge).A decline in QMLT correlated with duration of mechanical ventilation on day 7 (p=0.46,p<0.001) and with mNUTRIC score on day 3 and on day 7 of ICU stay or on the day of discharge (p=0.36,p <0.001 at day 3; p=0.44, p<0.001 at day 7 or on the day of discharge).The decline in QMLT did not correlate with the duration of ICU stay.A >25.97% decline in QMLT on day 7 of ICU stay was associated with a high area under the curve (AUC) (AUC 0.96; p<0.0001).