Changes in muscle tissue oxygenation during stagnant ischemia in septic patients

Objective To determine changes in the rate of thenar muscles tissue deoxygenation during stagnant ischemia in patients with severe sepsis and septic shock.Design and setting Prospective observational study in the medical ICU of a general hospital.Patients and participants Consecutive patients admitted to ICU with septic shock (n=6), severe sepsis (n=6), localized infection (n=3), and healthy volunteers (n=15).Interventions Upper limb ischemia was induced by rapid automatic pneumatic cuff inflation around upper arm.Measurements and results Thenar muscle tissue oxygen saturation (StO₂) was measured continuously by near-infrared spectroscopy before and during upper limb ischemia. StO₂ before intervention was comparable in patients with septic shock, severe sepsis, or localized infection and healthy volunteers (89 [65, 92]% vs. 82 [72, 91]% vs. 87 [85, 92]% vs. 83 [79, 93]%, respectively; p>0.1). The rate of StO₂ decrease during stagnant ischemia after initial hemodynamic stabilization was slower in septic shock patients than in those with severe sepsis or localized infection and in controls (–7.0 [–3.6, –11.0] %/min vs. –10.4 [–7.8, –13.3] %/min vs. –19.5 [–12.3, –23.3] vs. –37.4 [–27.3, –56.2] %/min, respectively; p=0.041). At ICU discharge the rate of StO₂ decrease did not differ between the septic shock, severe sepsis, and localized infection groups (–17.0 [–9.3, –28.9] %/min vs. –19.9 [–13.3, –23.6] %/min vs. –23.1 [–20.7, –26.2] %/min, respectively), but remained slower than in controls (p<0.01). The rate of StO₂ decrease was correlated with Sequential Organ Failure Assessment (SOFA) score (r=0.739, p<0.001).Conclusions After hemodynamic stabilization thenar muscle tissue oxygen saturation during stagnant ischemia decreases slower in septic shock patients than in patients with severe sepsis or localized infection and in healthy volunteers. During ICU stay and improvement of sepsis the muscle tissue deoxygenation rate increases in survivors of both septic shock and severe sepsis and was correlated with SOFA score.