The prognostic value of muscle StO2 in septic patients

Objective:: To quantify sepsis- induced alterations in changes in muscle tissue oxygenation ( StO(2)) after an ischemic challenge using near- infrared spectroscopy ( NIRS), and to test the hypothesis that these alterations are related to outcome. Design: Prospective study. Setting: Thirty- one- bed, university hospital Department of Intensive Care. Patients: Seventy- two patients with severe sepsis or septic shock, 18 hemodynamically stable, acutely ill patients without infection, and 18 healthy volunteers. Interventions: Three- minute occlusion of the brachial artery using a cuff inflated 50 mmHg above systolic arterial pressure. Measurements and main results: Thenar eminence StO2 was measured continuously by NIRS before ( StO(2)baseline), during, and after the 3- min occlusion. Changes in StO2 were assessed by the slope of increase in StO2 during the first 14 s following the ischemic period and by the difference between the maximum StO2 and StO2baseline (.). The slope was lower in septic patients than in controls and volunteers [ 2.3 ( 1.3 - 3.6), 4.8 ( 3.5 - 6.0), and 4.7 ( 3.2 - 6.3) %/ s, p < 0.001]. Delta was also significantly lower in septic patients than in the other groups. Slopes were lower in septic patients with than without shock [ 2.0 ( 1.2 - 2.9) vs 3.2 ( 1.8 - 4.5) %/ s, p < 0.05]. In 52 septic patients, in whom the slope was obtained every 24 h for 48 h, slopes were higher in survivors than in non- survivors and tended to increase in survivors but not in non- survivors. Conclusions: Altered recovery in StO2 after an ischemic challenge is frequent in septic patients and more pronounced in the presence of shock. The presence and persistence of these alterations in the first 24 h of sepsis are associated with worse outcome.