Background: The tissue oxygen saturation (StO₂) of skeletal muscle influences intensive care unit acquired weakness (ICU-AW). The purpose of this study was to examine whether mobilization improves StO₂ of quadriceps muscle for critically ill patients receiving mechanical ventilation.

Methods: This was a prospective, observational cohort study. Subjects were recruited critically ill patients receiving mechanical ventilation in ICU of two hospitals. We measured the StO₂ of the quadriceps muscle by using near-infrared spectroscopy. StO₂ was measured within 48 hours of ICU admission and immediately before ICU discharge.

Results: 27 patients (mean, 68.6 yrs. FiO2: 40.2%) were recruited into this study. 18 patients were survivor (66.7%), nine patients died. In eighteen survivors, StO₂ at ICU discharge (52.5±9.0%) was significantly higher than StO₂ (49.2±10.3%) at ICU admission (p < 0.05). Sixteen patients were ambulatory (88.9%) at ICU discharge. In nine fatalities, StO₂ at ICU admission was 43.6±9.1% and StO₂ at ICU discharge was 39.1±11.1%. StO₂ at ICU discharge in survivors was significantly higher than StO₂ in fatalities (p < 0.05).

Conclusion: These findings suggest that mobilization may improve StO₂ of quadriceps muscle for critically ill patients receiving mechanical ventilation.