Critical illness myopathy and disease severity scores. Normal (≥3 mV) and abnormal (< 3 mV) direct muscle stimulation compound muscle action potentials (dmCMAP), (a) simplified acute physiology score-II (SAPS-II) and (B) sequential organ failure assessment (SOFA) score on the first eight days after ICU admission. Patients with impaired muscle membrane excitability had significantly higher SAPS-II and SOFA scores during the first eight days after ICU admission. Nonparametric analysis of longitudinal data in a two-factorial design (1st factor: dmCMAP normal versus dmCMAP abnormal, 2nd factor: repetitions in time. The statistical analysis was the same for Figures 1 to 6, either focusing on values from the first eight days after ICU admission (Figures 1, 2, 4 and 5) or referring to a first and second interval between days 3 and 7 after ICU admission and between days 8 and 10 after ICU admission, respectively (Figures 3 and 6).