Illustrative case. Mean and SD volume variation is labeled for the critically ill groups. (A) Mean diaphragm volume drop comparison between septic and nonseptic patients. Volume drop was significantly greater in the septic patients compared with that in the nonseptic patients, P = 0.01. (B) Mean psoas volume drop comparison between septic and nonseptic patients. Volume drop was not affected by the presence of sepsis, P = 0.09.